Tagged your-feed-health

Has the Era of Overzealous Cleaning Finally Come to an End?

This week, the C.D.C. acknowledged what scientists have been saying for months: The risk of catching the coronavirus from surfaces is low.

When the coronavirus began to spread in the United States last spring, many experts warned of the danger posed by surfaces. Researchers reported that the virus could survive for days on plastic or stainless steel, and the Centers for Disease Control and Prevention advised that if someone touched one of these contaminated surfaces — and then touched their eyes, nose or mouth — they could become infected.

Americans responded in kind, wiping down groceries, quarantining mail and clearing drugstore shelves of Clorox wipes. Facebook closed two of its offices for a “deep cleaning.” New York’s Metropolitan Transportation Authority began disinfecting subway cars every night.

But the era of “hygiene theater” may have come to an unofficial end this week, when the C.D.C. updated its surface cleaning guidelines and noted that the risk of contracting the virus from touching a contaminated surface was less than 1 in 10,000.

“People can be affected with the virus that causes Covid-19 through contact with contaminated surfaces and objects,” Dr. Rochelle Walensky, the director of the C.D.C., said at a White House briefing on Monday. “However, evidence has demonstrated that the risk by this route of infection of transmission is actually low.”

The admission is long overdue, scientists say.

“Finally,” said Linsey Marr, an expert on airborne viruses at Virginia Tech. “We’ve known this for a long time and yet people are still focusing so much on surface cleaning.” She added, “There’s really no evidence that anyone has ever gotten Covid-19 by touching a contaminated surface.”

During the early days of the pandemic, many experts believed that the virus spread primarily through large respiratory droplets. These droplets are too heavy to travel long distances through the air but can fall onto objects and surfaces.

In this context, a focus on scrubbing down every surface seemed to make sense. “Surface cleaning is more familiar,” Dr. Marr said. “We know how to do it. You can see people doing it, you see the clean surface. And so I think it makes people feel safer.”

A “sanitization specialist” at an Applebee’s Grill and Bar in Westbury, N.Y., wiping down a used pen last year. Restaurants and other businesses have highlighted extra cleaning in their marketing since the pandemic began.
A “sanitization specialist” at an Applebee’s Grill and Bar in Westbury, N.Y., wiping down a used pen last year. Restaurants and other businesses have highlighted extra cleaning in their marketing since the pandemic began.Hiroko Masuike/The New York Times

But over the last year, it has become increasingly clear that the virus spreads primarily through the air — in both large and small droplets, which can remain aloft longer — and that scouring door handles and subway seats does little to keep people safe.

“The scientific basis for all this concern about surfaces is very slim — slim to none,” said Emanuel Goldman, a microbiologist at Rutgers University, who wrote last summer that the risk of surface transmission had been overblown. “This is a virus you get by breathing. It’s not a virus you get by touching.”

The C.D.C. has previously acknowledged that surfaces are not the primary way that the virus spreads. But the agency’s statements this week went farther.

“The most important part of this update is that they’re clearly communicating to the public the correct, low risk from surfaces, which is not a message that has been clearly communicated for the past year,” said Joseph Allen, a building safety expert at the Harvard T.H. Chan School of Public Health.

Catching the virus from surfaces remains theoretically possible, he noted. But it requires many things to go wrong: a lot of fresh, infectious viral particles to be deposited on a surface, and then for a relatively large quantity of them to be quickly transferred to someone’s hand and then to their face. “Presence on a surface does not equal risk,” Dr. Allen said.

In most cases, cleaning with simple soap and water — in addition to hand-washing and mask-wearing — is enough to keep the odds of surface transmission low, the C.D.C.’s updated cleaning guidelines say. In most everyday scenarios and environments, people do not need to use chemical disinfectants, the agency notes.

“What this does very usefully, I think, is tell us what we don’t need to do,” said Donald Milton, an aerosol scientist at the University of Maryland. “Doing a lot of spraying and misting of chemicals isn’t helpful.”

Still, the guidelines do suggest that if someone who has Covid-19 has been in a particular space within the last day, the area should be both cleaned and disinfected.

“Disinfection is only recommended in indoor settings — schools and homes — where there has been a suspected or confirmed case of Covid-19 within the last 24 hours,” Dr. Walensky said during the White House briefing. “Also, in most cases, fogging, fumigation and wide-area or electrostatic spraying is not recommended as a primary method of disinfection and has several safety risks to consider.”

And the new cleaning guidelines do not apply to health care facilities, which may require more intensive cleaning and disinfection.

Saskia Popescu, an infectious disease epidemiologist at George Mason University, said that she was happy to see the new guidance, which “reflects our evolving data on transmission throughout the pandemic.”

But she noted that it remained important to continue doing some regular cleaning — and maintaining good hand-washing practices — to reduce the risk of contracting not just the coronavirus but any other pathogens that might be lingering on a particular surface.

Dr. Allen said that the school and business officials he has spoken with this week expressed relief over the updated guidelines, which will allow them to pull back on some of their intensive cleaning regimens. “This frees up a lot of organizations to spend that money better,” he said.

Schools, businesses and other institutions that want to keep people safe should shift their attention from surfaces to air quality, he said, and invest in improved ventilation and filtration.

“This should be the end of deep cleaning,” Dr. Allen said, noting that the misplaced focus on surfaces has had real costs. “It has led to closed playgrounds, it has led to taking nets off basketball courts, it has led to quarantining books in the library. It has led to entire missed school days for deep cleaning. It has led to not being able to share a pencil. So that’s all that hygiene theater, and it’s a direct result of not properly classifying surface transmission as low risk.”

Roni Caryn Rabin contributed reporting

Researchers Are Hatching a Low-Cost Coronavirus Vaccine

A new formulation entering clinical trials in Brazil, Mexico, Thailand and Vietnam could change how the world fights the pandemic.

A new vaccine for Covid-19 that is entering clinical trials in Brazil, Mexico, Thailand and Vietnam could change how the world fights the pandemic. The vaccine, called NVD-HXP-S, is the first in clinical trials to use a new molecular design that is widely expected to create more potent antibodies than the current generation of vaccines. And the new vaccine could be far easier to make.

Existing vaccines from companies like Pfizer and Johnson & Johnson must be produced in specialized factories using hard-to-acquire ingredients. In contrast, the new vaccine can be mass-produced in chicken eggs — the same eggs that produce billions of influenza vaccines every year in factories around the world.

If NVD-HXP-S proves safe and effective, flu vaccine manufacturers could potentially produce well over a billion doses of it a year. Low- and middle-income countries currently struggling to obtain vaccines from wealthier countries may be able to make NVD-HXP-S for themselves or acquire it at low cost from neighbors.

“That’s staggering — it would be a game-changer,” said Andrea Taylor, assistant director of the Duke Global Health Innovation Center.

First, however, clinical trials must establish that NVD-HXP-S actually works in people. The first phase of clinical trials will conclude in July, and the final phase will take several months more. But experiments with vaccinated animals have raised hopes for the vaccine’s prospects.

“It’s a home run for protection,” said Dr. Bruce Innes of the PATH Center for Vaccine Innovation and Access, which has coordinated the development of NVD-HXP-S. “I think it’s a world-class vaccine.”

2P to the rescue

The molecular structure of HexaPro, a modified version of the SARS-CoV-2 spike protein, with its six key alterations shown as red and blue spheres.
The molecular structure of HexaPro, a modified version of the SARS-CoV-2 spike protein, with its six key alterations shown as red and blue spheres.University of Texas at Austin

Vaccines work by acquainting the immune system with a virus well enough to prompt a defense against it. Some vaccines contain entire viruses that have been killed; others contain just a single protein from the virus. Still others contain genetic instructions that our cells can use to make the viral protein.

Once exposed to a virus, or part of it, the immune system can learn to make antibodies that attack it. Immune cells can also learn to recognize infected cells and destroy them.

In the case of the coronavirus, the best target for the immune system is the protein that covers its surface like a crown. The protein, known as spike, latches onto cells and then allows the virus to fuse to them.

But simply injecting coronavirus spike proteins into people is not the best way to vaccinate them. That’s because spike proteins sometimes assume the wrong shape, and prompt the immune system to make the wrong antibodies.

Jason McLellan, a structural biologist at the University of Texas at Austin. His research on coronavirus spike proteins aided the development of the Pfizer, Moderna, Johnson & Johnson and Novavax vaccines.Ilana Panich-Linsman for The New York Times

This insight emerged long before the Covid-19 pandemic. In 2015, another coronavirus appeared, causing a deadly form of pneumonia called MERS. Jason McLellan, a structural biologist then at the Geisel School of Medicine at Dartmouth, and his colleagues set out to make a vaccine against it.

They wanted to use the spike protein as a target. But they had to reckon with the fact that the spike protein is a shape-shifter. As the protein prepares to fuse to a cell, it contorts from a tulip-like shape into something more akin to a javelin.

Scientists call these two shapes the prefusion and postfusion forms of the spike. Antibodies against the prefusion shape work powerfully against the coronavirus, but postfusion antibodies don’t stop it.

Dr. McLellan and his colleagues used standard techniques to make a MERS vaccine but ended up with a lot of postfusion spikes, useless for their purposes. Then they discovered a way to keep the protein locked in a tulip-like prefusion shape. All they had to do was change two of more than 1,000 building blocks in the protein into a compound called proline.

The resulting spike — called 2P, for the two new proline molecules it contained — was far more likely to assume the desired tulip shape. The researchers injected the 2P spikes into mice and found that the animals could easily fight off infections of the MERS coronavirus.

The team filed a patent for its modified spike, but the world took little notice of the invention. MERS, although deadly, is not very contagious and proved to be a relatively minor threat; fewer than 1,000 people have died of MERS since it first emerged in humans.

But in late 2019 a new coronavirus, SARS-CoV-2, emerged and began ravaging the world. Dr. McLellan and his colleagues swung into action, designing a 2P spike unique to SARS-CoV-2. In a matter of days, Moderna used that information to design a vaccine for Covid-19; it contained a genetic molecule called RNA with the instructions for making the 2P spike.

Other companies soon followed suit, adopting 2P spikes for their own vaccine designs and starting clinical trials. All three of the vaccines that have been authorized so far in the United States — from Johnson & Johnson, Moderna and Pfizer-BioNTech — use the 2P spike.

Other vaccine makers are using it as well. Novavax has had strong results with the 2P spike in clinical trials and is expected to apply to the Food and Drug Administration for emergency use authorization in the next few weeks. Sanofi is also testing a 2P spike vaccine and expects to finish clinical trials later this year.

Two prolines are good; six are better

Dr. McLellan’s ability to find lifesaving clues in the structure of proteins has earned him deep admiration in the vaccine world. “This guy is a genius,” said Harry Kleanthous, a senior program officer at the Bill & Melinda Gates Foundation. “He should be proud of this huge thing he’s done for humanity.”

But once Dr. McLellan and his colleagues handed off the 2P spike to vaccine makers, he turned back to the protein for a closer look. If swapping just two prolines improved a vaccine, surely additional tweaks could improve it even more.

“It made sense to try to have a better vaccine,” said Dr. McLellan, who is now an associate professor at the University of Texas at Austin.

In March, he joined forces with two fellow University of Texas biologists, Ilya Finkelstein and Jennifer Maynard. Their three labs created 100 new spikes, each with an altered building block. With funding from the Gates Foundation, they tested each one and then combined the promising changes in new spikes. Eventually, they created a single protein that met their aspirations.

The winner contained the two prolines in the 2P spike, plus four additional prolines found elsewhere in the protein. Dr. McLellan called the new spike HexaPro, in honor of its total of six prolines.

The structure of HexaPro was even more stable than 2P, the team found. It was also resilient, better able to withstand heat and damaging chemicals. Dr. McLellan hoped that its rugged design would make it potent in a vaccine.

Dr. McLellan also hoped that HexaPro-based vaccines would reach more of the world — especially low- and middle-income countries, which so far have received only a fraction of the total distribution of first-wave vaccines.

“The share of the vaccines they’ve received so far is terrible,” Dr. McLellan said.

To that end, the University of Texas set up a licensing arrangement for HexaPro that allows companies and labs in 80 low- and middle-income countries to use the protein in their vaccines without paying royalties.

Meanwhile, Dr. Innes and his colleagues at PATH were looking for a way to increase the production of Covid-19 vaccines. They wanted a vaccine that less wealthy nations could make on their own.

With a little help from eggs

The first wave of authorized Covid-19 vaccines require specialized, costly ingredients to make. Moderna’s RNA-based vaccine, for instance, needs genetic building blocks called nucleotides, as well as a custom-made fatty acid to build a bubble around them. Those ingredients must be assembled into vaccines in purpose-built factories.

The way influenza vaccines are made is a study in contrast. Many countries have huge factories for making cheap flu shots, with influenza viruses injected into chicken eggs. The eggs produce an abundance of new copies of the viruses. Factory workers then extract the viruses, weaken or kill them and then put them into vaccines.

The PATH team wondered if scientists could make a Covid-19 vaccine that could be grown cheaply in chicken eggs. That way, the same factories that make flu shots could make Covid-19 shots as well.

In New York, a team of scientists at the Icahn School of Medicine at Mount Sinai knew how to make just such a vaccine, using a bird virus called Newcastle disease virus that is harmless in humans.

For years, scientists had been experimenting with Newcastle disease virus to create vaccines for a range of diseases. To develop an Ebola vaccine, for example, researchers added an Ebola gene to the Newcastle disease virus’s own set of genes.

The scientists then inserted the engineered virus into chicken eggs. Because it is a bird virus, it multiplied quickly in the eggs. The researchers ended up with Newcastle disease viruses coated with Ebola proteins.

At Mount Sinai, the researchers set out to do the same thing, using coronavirus spike proteins instead of Ebola proteins. When they learned about Dr. McLellan’s new HexaPro version, they added that to the Newcastle disease viruses. The viruses bristled with spike proteins, many of which had the desired prefusion shape. In a nod to both the Newcastle disease virus and the HexaPro spike, they called it NDV-HXP-S.

PATH arranged for thousands of doses of NDV-HXP-S to be produced in a Vietnamese factory that normally makes influenza vaccines in chicken eggs. In October, the factory sent the vaccines to New York to be tested. The Mount Sinai researchers found that NDV-HXP-S conferred powerful protection in mice and hamsters.

“I can honestly say I can protect every hamster, every mouse in the world against SARS-CoV-2,” Dr. Peter Palese, the leader of the research, said. “But the jury’s still out about what it does in humans.”

The potency of the vaccine brought an extra benefit: The researchers needed fewer viruses for an effective dose. A single egg may yield five to 10 doses of NDV-HXP-S, compared to one or two doses of influenza vaccines.

“We are very excited about this, because we think it’s a way of making a cheap vaccine,” Dr. Palese said.

A nurse administering the NDV-HXP-S  vaccine to a volunteer at Mahidol University in Bangkok during the country’s first human trial.Government Pharmaceutical Organization of Thailand, via Agence France-Presse — Getty Images

PATH then connected the Mount Sinai team with influenza vaccine makers. On March 15, Vietnam’s Institute of Vaccines and Medical Biologicals announced the start of a clinical trial of NDV-HXP-S. A week later, Thailand’s Government Pharmaceutical Organization followed suit. On March 26, Brazil’s Butantan Institute said it would ask for authorization to begin its own clinical trials of NDV-HXP-S.

Meanwhile, the Mount Sinai team has also licensed the vaccine to the Mexican vaccine maker Avi-Mex as an intranasal spray. The company will start clinical trials to see if the vaccine is even more potent in that form.

To the nations involved, the prospect of making the vaccines entirely on their own was appealing. “This vaccine production is produced by Thai people for Thai people,” Thailand’s health minister, Anutin Charnvirakul, said at the announcement in Bangkok.

From left, Dimas Covas, director of the Butantan Institute in Brazil; João Doria, governor of the state of São Paulo; and Jean Gorinchteyn, the state health secretary, announcing the ButanVac Covid-19 vaccine candidate against in São Paulo on March 26. Miguel Schincariol/Agence France-Presse — Getty Images

In Brazil, the Butantan Institute trumpeted its version of NDV-HXP-S as “the Brazilian vaccine,” one that would be “produced entirely in Brazil, without depending on imports.”

Ms. Taylor, of the Duke Global Health Innovation Center, was sympathetic. “I could understand why that would really be such an attractive prospect,” she said. “They’ve been at the mercy of global supply chains.”

Madhavi Sunder, an expert on intellectual property at Georgetown Law School, cautioned that NDV-HXP-S would not immediately help countries like Brazil as they grappled with the current wave of Covid-19 infections. “We’re not talking 16 billion doses in 2020,” she said.

Instead, the strategy will be important for long-term vaccine production — not just for Covid-19 but for other pandemics that may come in the future. “It sounds super promising,” she said.

In the meantime, Dr. McLellan has returned to the molecular drawing board to try to make a third version of their spike that is even better than HexaPro.

“There’s really no end to this process,” he said. “The number of permutations is almost infinite. At some point, you’d have to say, ‘This is the next generation.’”

Researchers Are Hatching a Low-Cost Covid-19 Vaccine

A new formulation entering clinical trials in Brazil, Mexico, Thailand and Vietnam could change how the world fights the pandemic.

A new vaccine for Covid-19 that is entering clinical trials in Brazil, Mexico, Thailand and Vietnam could change how the world fights the pandemic. The vaccine, called NVD-HXP-S, is the first in clinical trials to use a new molecular design that is widely expected to create more potent antibodies than the current generation of vaccines. And the new vaccine could be far easier to make.

Existing vaccines from companies like Pfizer and Johnson & Johnson must be produced in specialized factories using hard-to-acquire ingredients. In contrast, the new vaccine can be mass-produced in chicken eggs — the same eggs that produce billions of influenza vaccines every year in factories around the world.

If NVD-HXP-S proves safe and effective, flu vaccine manufacturers could potentially produce well over a billion doses of it a year. Low- and middle-income countries currently struggling to obtain vaccines from wealthier countries may be able to make NVD-HXP-S for themselves or acquire it at low cost from neighbors.

“That’s staggering — it would be a game-changer,” said Andrea Taylor, assistant director of the Duke Global Health Innovation Center.

First, however, clinical trials must establish that NVD-HXP-S actually works in people. The first phase of clinical trials will conclude in July, and the final phase will take several months more. But experiments with vaccinated animals have raised hopes for the vaccine’s prospects.

“It’s a home run for protection,” said Dr. Bruce Innes of the PATH Center for Vaccine Innovation and Access, which has coordinated the development of NVD-HXP-S. “I think it’s a world-class vaccine.”

2P to the rescue

The molecular structure of HexaPro, a modified version of the SARS-CoV-2 spike protein, with its six key alterations shown as red and blue spheres.
The molecular structure of HexaPro, a modified version of the SARS-CoV-2 spike protein, with its six key alterations shown as red and blue spheres.University of Texas at Austin

Vaccines work by acquainting the immune system with a virus well enough to prompt a defense against it. Some vaccines contain entire viruses that have been killed; others contain just a single protein from the virus. Still others contain genetic instructions that our cells can use to make the viral protein.

Once exposed to a virus, or part of it, the immune system can learn to make antibodies that attack it. Immune cells can also learn to recognize infected cells and destroy them.

In the case of the coronavirus, the best target for the immune system is the protein that covers its surface like a crown. The protein, known as spike, latches onto cells and then allows the virus to fuse to them.

But simply injecting coronavirus spike proteins into people is not the best way to vaccinate them. That’s because spike proteins sometimes assume the wrong shape, and prompt the immune system to make the wrong antibodies.

Jason McLellan, a structural biologist at the University of Texas at Austin. His research on coronavirus spike proteins aided the development of the Pfizer, Moderna, Johnson & Johnson and Novavax vaccines.Ilana Panich-Linsman for The New York Times

This insight emerged long before the Covid-19 pandemic. In 2015, another coronavirus appeared, causing a deadly form of pneumonia called MERS. Jason McLellan, a structural biologist then at the Geisel School of Medicine at Dartmouth, and his colleagues set out to make a vaccine against it.

They wanted to use the spike protein as a target. But they had to reckon with the fact that the spike protein is a shape-shifter. As the protein prepares to fuse to a cell, it contorts from a tulip-like shape into something more akin to a javelin.

Scientists call these two shapes the prefusion and postfusion forms of the spike. Antibodies against the prefusion shape work powerfully against the coronavirus, but postfusion antibodies don’t stop it.

Dr. McLellan and his colleagues used standard techniques to make a MERS vaccine but ended up with a lot of postfusion spikes, useless for their purposes. Then they discovered a way to keep the protein locked in a tulip-like prefusion shape. All they had to do was change two of more than 1,000 building blocks in the protein into a compound called proline.

The resulting spike — called 2P, for the two new proline molecules it contained — was far more likely to assume the desired tulip shape. The researchers injected the 2P spikes into mice and found that the animals could easily fight off infections of the MERS coronavirus.

The team filed a patent for its modified spike, but the world took little notice of the invention. MERS, although deadly, is not very contagious and proved to be a relatively minor threat; fewer than 1,000 people have died of MERS since it first emerged in humans.

But in late 2019 a new coronavirus, SARS-CoV-2, emerged and began ravaging the world. Dr. McLellan and his colleagues swung into action, designing a 2P spike unique to SARS-CoV-2. In a matter of days, Moderna used that information to design a vaccine for Covid-19; it contained a genetic molecule called RNA with the instructions for making the 2P spike.

Other companies soon followed suit, adopting 2P spikes for their own vaccine designs and starting clinical trials. All three of the vaccines that have been authorized so far in the United States — from Johnson & Johnson, Moderna and Pfizer-BioNTech — use the 2P spike.

Other vaccine makers are using it as well. Novavax has had strong results with the 2P spike in clinical trials and is expected to apply to the Food and Drug Administration for emergency use authorization in the next few weeks. Sanofi is also testing a 2P spike vaccine and expects to finish clinical trials later this year.

Two prolines are good; six are better

Dr. McLellan’s ability to find lifesaving clues in the structure of proteins has earned him deep admiration in the vaccine world. “This guy is a genius,” said Harry Kleanthous, a senior program officer at the Bill & Melinda Gates Foundation. “He should be proud of this huge thing he’s done for humanity.”

But once Dr. McLellan and his colleagues handed off the 2P spike to vaccine makers, he turned back to the protein for a closer look. If swapping just two prolines improved a vaccine, surely additional tweaks could improve it even more.

“It made sense to try to have a better vaccine,” said Dr. McLellan, who is now an associate professor at the University of Texas at Austin.

In March, he joined forces with two fellow University of Texas biologists, Ilya Finkelstein and Jennifer Maynard. Their three labs created 100 new spikes, each with an altered building block. With funding from the Gates Foundation, they tested each one and then combined the promising changes in new spikes. Eventually, they created a single protein that met their aspirations.

The winner contained the two prolines in the 2P spike, plus four additional prolines found elsewhere in the protein. Dr. McLellan called the new spike HexaPro, in honor of its total of six prolines.

The structure of HexaPro was even more stable than 2P, the team found. It was also resilient, better able to withstand heat and damaging chemicals. Dr. McLellan hoped that its rugged design would make it potent in a vaccine.

Dr. McLellan also hoped that HexaPro-based vaccines would reach more of the world — especially low- and middle-income countries, which so far have received only a fraction of the total distribution of first-wave vaccines.

“The share of the vaccines they’ve received so far is terrible,” Dr. McLellan said.

To that end, the University of Texas set up a licensing arrangement for HexaPro that allows companies and labs in 80 low- and middle-income countries to use the protein in their vaccines without paying royalties.

Meanwhile, Dr. Innes and his colleagues at PATH were looking for a way to increase the production of Covid-19 vaccines. They wanted a vaccine that less wealthy nations could make on their own.

With a little help from eggs

The first wave of authorized Covid-19 vaccines require specialized, costly ingredients to make. Moderna’s RNA-based vaccine, for instance, needs genetic building blocks called nucleotides, as well as a custom-made fatty acid to build a bubble around them. Those ingredients must be assembled into vaccines in purpose-built factories.

The way influenza vaccines are made is a study in contrast. Many countries have huge factories for making cheap flu shots, with influenza viruses injected into chicken eggs. The eggs produce an abundance of new copies of the viruses. Factory workers then extract the viruses, weaken or kill them and then put them into vaccines.

The PATH team wondered if scientists could make a Covid-19 vaccine that could be grown cheaply in chicken eggs. That way, the same factories that make flu shots could make Covid-19 shots as well.

In New York, a team of scientists at the Icahn School of Medicine at Mount Sinai knew how to make just such a vaccine, using a bird virus called Newcastle disease virus that is harmless in humans.

For years, scientists had been experimenting with Newcastle disease virus to create vaccines for a range of diseases. To develop an Ebola vaccine, for example, researchers added an Ebola gene to the Newcastle disease virus’s own set of genes.

The scientists then inserted the engineered virus into chicken eggs. Because it is a bird virus, it multiplied quickly in the eggs. The researchers ended up with Newcastle disease viruses coated with Ebola proteins.

At Mount Sinai, the researchers set out to do the same thing, using coronavirus spike proteins instead of Ebola proteins. When they learned about Dr. McLellan’s new HexaPro version, they added that to the Newcastle disease viruses. The viruses bristled with spike proteins, many of which had the desired prefusion shape. In a nod to both the Newcastle disease virus and the HexaPro spike, they called it NDV-HXP-S.

PATH arranged for thousands of doses of NDV-HXP-S to be produced in a Vietnamese factory that normally makes influenza vaccines in chicken eggs. In October, the factory sent the vaccines to New York to be tested. The Mount Sinai researchers found that NDV-HXP-S conferred powerful protection in mice and hamsters.

“I can honestly say I can protect every hamster, every mouse in the world against SARS-CoV-2,” Dr. Peter Palese, the leader of the research, said. “But the jury’s still out about what it does in humans.”

The potency of the vaccine brought an extra benefit: The researchers needed fewer viruses for an effective dose. A single egg may yield five to 10 doses of NDV-HXP-S, compared to one or two doses of influenza vaccines.

“We are very excited about this, because we think it’s a way of making a cheap vaccine,” Dr. Palese said.

A nurse administering the NDV-HXP-S  vaccine to a volunteer at Mahidol University in Bangkok during the country’s first human trial.Government Pharmaceutical Organization of Thailand, via Agence France-Presse — Getty Images

PATH then connected the Mount Sinai team with influenza vaccine makers. On March 15, Vietnam’s Institute of Vaccines and Medical Biologicals announced the start of a clinical trial of NDV-HXP-S. A week later, Thailand’s Government Pharmaceutical Organization followed suit. On March 26, Brazil’s Butantan Institute said it would ask for authorization to begin its own clinical trials of NDV-HXP-S.

Meanwhile, the Mount Sinai team has also licensed the vaccine to the Mexican vaccine maker Avi-Mex as an intranasal spray. The company will start clinical trials to see if the vaccine is even more potent in that form.

To the nations involved, the prospect of making the vaccines entirely on their own was appealing. “This vaccine production is produced by Thai people for Thai people,” Thailand’s health minister, Anutin Charnvirakul, said at the announcement in Bangkok.

From left, Dimas Covas, director of the Butantan Institute in Brazil; João Doria, governor of the state of São Paulo; and Jean Gorinchteyn, the state health secretary, announcing the ButanVac Covid-19 vaccine candidate against in São Paulo on March 26. Miguel Schincariol/Agence France-Presse — Getty Images

In Brazil, the Butantan Institute trumpeted its version of NDV-HXP-S as “the Brazilian vaccine,” one that would be “produced entirely in Brazil, without depending on imports.”

Ms. Taylor, of the Duke Global Health Innovation Center, was sympathetic. “I could understand why that would really be such an attractive prospect,” she said. “They’ve been at the mercy of global supply chains.”

Madhavi Sunder, an expert on intellectual property at Georgetown Law School, cautioned that NDV-HXP-S would not immediately help countries like Brazil as they grappled with the current wave of Covid-19 infections. “We’re not talking 16 billion doses in 2020,” she said.

Instead, the strategy will be important for long-term vaccine production — not just for Covid-19 but for other pandemics that may come in the future. “It sounds super promising,” she said.

In the meantime, Dr. McLellan has returned to the molecular drawing board to try to make a third version of their spike that is even better than HexaPro.

“There’s really no end to this process,” he said. “The number of permutations is almost infinite. At some point, you’d have to say, ‘This is the next generation.’”

Getting One Vaccine Is Good. How About Mix-and-Match?

Researchers are exploring the possible benefits of pairing doses from two different Covid-19 vaccines.

In January, Britain made a change to its vaccine guidelines that shocked many health experts: If the second dose of one vaccine wasn’t available, patients could be given a different one.

The new rule was based on sheer guesswork; there was no scientific data at the time demonstrating that mixing two coronavirus vaccines was safe and effective. But that may change soon.

In February, researchers at the University of Oxford began a trial in which volunteers received a dose of the Pfizer-BioNTech vaccine followed by a dose of AstraZeneca’s formulation, or vice versa. This month, the researchers will start analyzing the blood of the subjects to see how well the mix-and-match approach works.

As growing numbers of vaccines are being authorized, researchers are testing other combinations. A few are in clinical trials, while others are being tested in animals for now.

Mixing vaccines might do more than just help overcome supply bottlenecks. Some researchers suspect that a pair of different vaccines might work better than two doses of the same one.

“I think we’re on the cusp of some interesting data,” said Adam Wheatley, an immunologist at the University of Melbourne in Australia.

The concept of mixing vaccines — sometimes called a heterologous prime-boost — is not new to our pandemic era. For decades, researchers have investigated the approach, hoping to find potent combinations against a range of viruses, such as influenza, H.I.V. and Ebola.

But scientists had little to show for all that research. It was easy enough to demonstrate that two vaccines may work well together in a mouse. But running full-blown clinical trials on a combination of vaccines is a tall order.

“For a single company to develop two parallel arms of a vaccine is twice the work and twice the cost,” Dr. Wheatley said.

Some of the early successes for heterologous prime-boosts came in the search for vaccines for Ebola. Many researchers focused their efforts on presenting the immune system with a protein found on the surface of the Ebola virus.

The gene for that protein was inserted into a different, harmless virus. When people received an injection of the vaccine, the harmless virus entered their cells; the cells then read the instructions in the Ebola gene and mass-produced Ebola’s surface protein. The immune system encountered the Ebola protein and made antibodies against it. And those antibodies protected the vaccinated people if they became infected with a full-blown Ebola virus.

This type of vaccine, called a viral vector vaccine, came with a big risk: The recipients might develop immunity to the viral vector after just the first dose. When the second dose arrived, their immune systems could swiftly wipe out the viral vector before it delivered its payload.

A number of vaccine makers decided to sidestep this potential threat by using different viruses for each dose. That way, the viral vectors in the second dose would be as new to the immune system as the first was. In 2017, for example, researchers at the Gamaleya Research Institute in Russia created an Ebola vaccine whose first dose contained a virus called an adenovirus. The second shot used another virus, called vesicular stomatitis virus.

When the Covid-19 pandemic began last year, the Gamaleya researchers used a similar strategy to create vaccines against the new coronavirus. The first dose used the same adenovirus as in their Ebola vaccine, called Ad5. The second dose contained a different human adenovirus, Ad26. The researches inserted a gene into both viruses for the protein on the surface of the coronavirus, called spike.

Studies revealed that the vaccine, now known as Sputnik V, provided a strong defense against Covid-19. In clinical trials, the researchers found that it had an efficacy of 91.6 percent. Sputnik V is now in use in Russia and 56 other countries.

Recently, the Gamaleya institute joined forces with AstraZeneca, which makes its own Covid-19 vaccine. AstraZeneca’s consists of two doses of a chimpanzee adenovirus called ChAdOx1. Last week, the company reported that its vaccine had an efficacy of 76 percent.

The Gamaleya and AstraZeneca teams want to see how well their vaccines work together. They have registered a pair of clinical trials in which volunteers will receive a dose of AstraZeneca’s ChAdOx1 and another of Sputnik V’s Ad26.

A spokesman for AstraZeneca said that one trial in Azerbaijan is underway, and a second, in Russia, is still under review by the country’s ministry of health.

Dr. Jakob Cramer, the head of clinical development at CEPI, a vaccine development organization, said that vaccines using viral vectors were not the only kind that might benefit from mixing. In fact, certain combinations might provoke a different, more effective immune response than a single type of vaccine. “Immunologically, there are several arguments in favor of exploring heterologous priming,” Dr. Kramer said.

Another kind of Covid-19 vaccine being tested contains the actual spike protein, rather than genetic instructions for it. Some of the vaccines contain the entire protein; others contain just a fragment of it. Currently, there are 29 protein-based vaccines for Covid-19 in clinical trials, although none have been authorized yet.

Dr. Wheatley and his colleagues have been testing protein-based vaccines in mice. They injected the full spike protein into the animals as a first dose. For the second dose, they injected only the tip of the spike, a region known as the receptor-binding domain, or R.B.D.

Dr. Wheatley and his colleagues found that the mixture worked better than two doses of the spike or of the R.B.D.

The researchers suspect that the first dose produces a broad range of antibodies that can stick to spots along the length of the spike protein, and that the second dose delivers a big supply of particularly potent antibodies to the tip of the spike. Together, the assortment of antibodies does a better job of stopping the coronavirus.

“You’re able to basically take that initial immunity that was elicited to that spike vaccine, and then really focus it down onto that R.B.D.,” Dr. Wheatley said.

Other combinations of vaccines may bring benefits of their own. Some vaccines, especially protein-based ones, do a good job of generating antibodies. Others, such as viral vectors, are better at training immune cells. A viral vector followed by a protein boost might offer the best of both worlds.

John Moore, a virologist at Weill Cornell Medicine, cautioned that there was no guarantee that clinical trials would reveal a benefit to mixing vaccines. In the search for an H.I.V. vaccine, researchers tried combining viral vectors and protein boost without success, he noted. Still, Dr. Moore said, the story might turn out differently for coronavirus vaccines.

“I’d like to see these studies done,” he said. “Doing it in the Covid space is completely rational, but may not be necessary.”

Some researchers are investigating heterologous vaccines not to find a superior mixture, but simply to open up more options for countries desperate to vaccinate their populations. Last week, India held back exports of vaccines to other countries as it grappled with a surge of Covid-19. For countries that were counting on those vaccines, a safe alternative for second doses could save lives.

After Britain was criticized in January for suggesting that vaccines could be mixed, researchers at the University of Oxford set out to put the idea to a formal test. In a trial called Com-Cov, they recruited 830 volunteers to test the two vaccines authorized by the British government: AstraZeneca’s adenovirus-based vaccine and the vaccine by Pfizer-BioNTech.

Pfizer-BioNTech’s vaccine uses a fundamentally different technology to produce spike proteins in the body. It contains tiny bubbles with genetic molecules called RNA. Once the bubbles fuse to cells, the cells use the RNA to make spike proteins.

One group of volunteers is receiving a Pfizer-BioNTech shot followed by AstraZeneca, while another will receive them in the reverse order. The other volunteers are receiving the standard two-dose version of the vaccines.

Later this month, the Oxford team will draw blood from the volunteers, examining their antibodies and immune cells to see whether the heterologous prime-boost creates an immune response roughly as strong as two doses of each of the authorized vaccines.

If more vaccines are authorized in Britain, the Com-Cov team may add them to the trial. Dr. Matthew Snape, who is leading the Com-COV trial, hopes it will be useful not just to his own country but to others that will be trying to vaccinate their citizens over the next few years.

“It might be that actually this flexibility becomes essential in the future,” he said.

Dr. Cramer said CEPI is planning to support additional heterologous prime-boost studies. There are plenty of possible studies to run. Worldwide, 13 vaccines are now in use against Covid-19, with 67 more in clinical trials.

“In the current situation, we have a quite a luxurious position of having so many advanced, effective vaccines,” Dr. Wheatley said.

As the number of authorized vaccines grows, the possible combinations in which they can be used will explode. Recently, researchers at China’s National Institutes for Food and Drug Control scaled up their research on heterologous prime-boosts by trying out four different vaccines that have either been authorized in China or are in late-stage clinical trials there — vaccines based on adenoviruses, proteins, RNA and coronaviruses that have been inactivated with chemicals.

The researchers injected mice with a first dose of one vaccine, then a second dose of another. Some of the combinations caused the mice to produce stronger immune responses than mice that received the same vaccine for both doses.

Whether scientists carry out more experiments on other vaccines will depend on the willingness of the vaccine manufacturers. “You’re requiring quite large pharmaceutical companies to play nice together,” Dr. Wheatley said.

Dr. Bernard Moss, a virologist at the National Institute of Allergy and Infectious Diseases, suspects that a number of companies will be willing to let their vaccines be tested in combinations. “It’s always better to be a part of something that is going to be used,” he said, “than to wholly own something that isn’t.”

One Vaccine Is Good. How About Mixing Two?

Researchers are exploring the possible benefits of combining doses from two different Covid-19 vaccines.

In January, Britain made a change to its vaccine guidelines that shocked many health experts: If the second dose of one vaccine wasn’t available, patients could be given a different one.

The new rule was based on sheer guesswork; there was no scientific data at the time demonstrating that mixing two coronavirus vaccines was safe and effective. But that may change soon.

In February, researchers at the University of Oxford began a trial in which volunteers received a dose of the Pfizer-BioNTech vaccine followed by a dose of AstraZeneca’s formulation, or vice versa. This month, the researchers will start analyzing the blood of the subjects to see how well the mix-and-match approach works.

As a growing number of vaccines are being authorized, researchers are testing other combinations. A few are in clinical trials, while others are being tested in animals for now.

Mixing vaccines might do more than just help overcome supply bottlenecks. Some researchers suspect that a pair of different vaccines might work better than two doses of the same one.

“I think we’re on the cusp of some interesting data,” said Adam Wheatley, an immunologist at the University of Melbourne in Australia.

The concept of mixing vaccines — sometimes called a heterologous prime-boost — is not new to our pandemic era. For decades, researchers have investigated the approach, hoping to find potent combinations against a range of viruses, such as influenza, H.I.V. and Ebola.

But scientists had little to show for all that research. It was easy enough to demonstrate that two vaccines may work well together in a mouse. But running full-blown clinical trials on a combination of vaccines is a tall order.

“For a single company to develop two parallel arms of a vaccine is twice the work and twice the cost,” Dr. Wheatley said.

Some of the early successes for heterologous prime-boosts came in the search for vaccines for Ebola. Many researchers focused their efforts on presenting the immune system with a protein found on the surface of the Ebola virus.

The gene for that protein was inserted into a different, harmless virus. When people received an injection of the vaccine, the harmless virus entered their cells; the cells then read the instructions in the Ebola gene and mass-produced Ebola’s surface protein. The immune system encountered the Ebola protein and made antibodies against it. And those antibodies protected the vaccinated people if they became infected with a full-blown Ebola virus.

This type of vaccine, called a viral vector vaccine, came with a big risk: The recipients might develop immunity to the viral vector after just the first dose. When the second dose arrived, their immune systems could swiftly wipe out the viral vector before it delivered its payload.

A number of vaccine makers decided to sidestep this potential threat by using different viruses for each dose. That way, the viral vectors in the second dose would be as new to the immune system as the first was. In 2017, for example, researchers at the Gamaleya Research Institute in Russia created an Ebola vaccine whose first dose contained a virus called an adenovirus. The second shot used another virus, called vesicular stomatitis virus.

When the Covid-19 pandemic began last year, the Gamaleya researchers used a similar strategy to create vaccines against the new coronavirus. The first dose used the same adenovirus as in their Ebola vaccine, called Ad5. The second dose contained a different human adenovirus, Ad26. The researches inserted a gene into both viruses for the protein on the surface of the coronavirus, called spike.

Studies revealed that the vaccine, now known as Sputnik V, provided a strong defense against Covid-19. In clinical trials, the researchers found that it had an efficacy of 91.6 percent. Sputnik V is now in use in Russia and 56 other countries.

Recently, the Gamaleya institute joined forces with AstraZeneca, which makes its own Covid-19 vaccine. AstraZeneca’s consists of two doses of a chimpanzee adenovirus called ChAdOx1. Last week, the company reported that its vaccine had an efficacy of 76 percent.

The Gamaleya and AstraZeneca teams want to see how well their vaccines work together. They have registered a pair of clinical trials in which volunteers will receive a dose of AstraZeneca’s ChAdOx1 and another of Sputnik V’s Ad26.

A spokesman for AstraZeneca said that one trial in Azerbaijan is underway, and a second, in Russia, is still under review by the country’s ministry of health.

Dr. Jakob Cramer, the head of clinical development at CEPI, a vaccine development organization, said that vaccines using viral vectors were not the only kind that might benefit from mixing. In fact, certain combinations might provoke a different, more effective immune response than a single type of vaccine. “Immunologically, there are several arguments in favor of exploring heterologous priming,” Dr. Kramer said.

Another kind of Covid-19 vaccine being tested contains the actual spike protein, rather than genetic instructions for it. Some of the vaccines contain the entire protein; others contain just a fragment of it. Currently, there are 29 protein-based vaccines for Covid-19 in clinical trials, although none have been authorized yet.

Dr. Wheatley and his colleagues have been testing protein-based vaccines in mice. They injected the full spike protein into the animals as a first dose. For the second dose, they injected only the tip of the spike, a region known as the receptor-binding domain, or R.B.D.

Dr. Wheatley and his colleagues found that the mixture worked better than two doses of the spike or of the R.B.D.

The researchers suspect that the first dose produces a broad range of antibodies that can stick to spots along the length of the spike protein, and that the second dose delivers a big supply of particularly potent antibodies to the tip of the spike. Together, the assortment of antibodies does a better job of stopping the coronavirus.

“You’re able to basically take that initial immunity that was elicited to that spike vaccine, and then really focus it down onto that R.B.D.,” Dr. Wheatley said.

Other combinations of vaccines may bring benefits of their own. Some vaccines, especially protein-based ones, do a good job of generating antibodies. Others, such as viral vectors, are better at training immune cells. A viral vector followed by a protein boost might offer the best of both worlds.

John Moore, a virologist at Weill Cornell Medicine, cautioned that there was no guarantee that clinical trials would reveal a benefit to mixing vaccines. In the search for an H.I.V. vaccine, researchers tried combining viral vectors and protein boost without success, he noted. Still, Dr. Moore said, the story might turn out differently for coronavirus vaccines.

“I’d like to see these studies done,” he said. “Doing it in the Covid space is completely rational, but may not be necessary.”

Some researchers are investigating heterologous vaccines not to find a superior mixture, but simply to open up more options for countries desperate to vaccinate their populations. Last week, India held back exports of vaccines to other countries as it grappled with a surge of Covid-19. For countries that were counting on those vaccines, a safe alternative for second doses could save lives.

After Britain was criticized in January for suggesting that vaccines could be mixed, researchers at the University of Oxford set out to put the idea to a formal test. In a trial called Com-Cov, they recruited 830 volunteers to test the two vaccines authorized by the British government: AstraZeneca’s adenovirus-based vaccine and the vaccine by Pfizer-BioNTech.

Pfizer-BioNTech’s vaccine uses a fundamentally different technology to produce spike proteins in the body. It contains tiny bubbles with genetic molecules called RNA. Once the bubbles fuse to cells, the cells use the RNA to make spike proteins.

One group of volunteers is receiving a Pfizer-BioNTech shot followed by AstraZeneca, while another will receive them in the reverse order. The other volunteers are receiving the standard two-dose version of the vaccines.

Later this month, the Oxford team will draw blood from the volunteers, examining their antibodies and immune cells to see whether the heterologous prime-boost creates an immune response roughly as strong as two doses of each of the authorized vaccines.

If more vaccines are authorized in Britain, the Com-Cov team may add them to the trial. Dr. Matthew Snape, who is leading the Com-COV trial, hopes it will be useful not just to his own country but to others that will be trying to vaccinate their citizens over the next few years.

“It might be that actually this flexibility becomes essential in the future,” he said.

Dr. Cramer said CEPI is planning to support additional heterologous prime-boost studies. There are plenty of possible studies to run. Worldwide, 13 vaccines are now in use against Covid-19, with 67 more in clinical trials.

“In the current situation, we have a quite a luxurious position of having so many advanced, effective vaccines,” Dr. Wheatley said.

As the number of authorized vaccines grows, the possible combinations in which they can be used will explode. Recently, researchers at China’s National Institutes for Food and Drug Control scaled up their research on heterologous prime-boosts by trying out four different vaccines that have either been authorized in China or are in late-stage clinical trials there — vaccines based on adenoviruses, proteins, RNA and coronaviruses that have been inactivated with chemicals.

The researchers injected mice with a first dose of one vaccine, then a second dose of another. Some of the combinations caused the mice to produce stronger immune responses than mice that received the same vaccine for both doses.

Whether scientists carry out more experiments on other vaccines will depend on the willingness of the vaccine manufacturers. “You’re requiring quite large pharmaceutical companies to play nice together,” Dr. Wheatley said.

Dr. Bernard Moss, a virologist at the National Institute of Allergy and Infectious Diseases, suspects that a number of companies will be willing to let their vaccines be tested in combinations. “It’s always better to be a part of something that is going to be used,” he said, “than to wholly own something that isn’t.”

Why It Pays to Think Outside the Box on Coronavirus Tests

Universities and other institutions looking to protect themselves from Covid-19 may benefit from sharing their testing resources with the wider community, a new study suggests.

Last year, when the National Football League decided to stage its season in the midst of the coronavirus pandemic, it went all-in on testing. The league tested all players and personnel before they reported for summer training camp, and continued near-daily testing in the months that followed. Between Aug. 1 and the Super Bowl in early February, the N.F.L. administered almost one million tests to players and staff.

Many other organizations have sought safety in mass testing. The University of Illinois is testing its students, faculty and staff twice a week and has conducted more than 1.6 million tests since July. Major corporations, from Amazon to Tyson Foods, have rolled out extensive testing programs for their own employees.

Now, a new analysis suggests that schools, businesses and other organizations that want to keep themselves safe should think beyond strictly themselves. By dedicating a substantial proportion of their tests to people in the surrounding community, institutions could reduce the number of Covid-19 cases among their members by as much as 25 percent, researchers report in a new paper, which has not yet been published in a scientific journal.

“It’s natural in an outbreak for people to become self-serving, self-focused,” said Dr. Pardis Sabeti, a computational biologist at Harvard University and the Broad Institute who lead the analysis. But, she added, “If you’ve been in enough outbreaks you just understand that testing in a box doesn’t makes sense. These things are communicable, and they’re coming in from the community.”

The study has “really profound implications, especially if others can replicate it, said David O’Connor, a virologist at the University of Wisconsin, Madison, who was not involved in the analysis but reviewed a draft of the paper. As the pandemic enters its second year, he said, “We want to start using more sophisticated modeling and probably economic theory to inform what an optimal testing program would look like.”

Dr. Sabeti is an epidemic veteran, part of teams that responded to an Ebola outbreak in West Africa in 2014 and a mumps outbreak in the Boston area a few years later. When the coronavirus closed down the country last spring, many colleges and universities sought her advice on how to safely reopen.

At a time when testing resources were in short supply, many of these institutions were proposing intensive, expensive testing regimens focused entirely on their own members. Again and again, Dr. Sabeti suggested that universities think more broadly, and allocate some of their tests to people who might be friends, family members or neighbors of their students and employees.

“The metaphor I often used on the calls was to say, ‘You’re in a drought in a place with a lot of forest fires, and you have a shortage of fire alarms,’” she recalled. “‘And if you run out and buy every fire alarm and install it in your own house, you’ll be able to pick up a fire the moment it hits your house, but at that point it’s burning to the ground.’”

Still, convincing university officials to divert precious testing resources away from their own institutions was a hard sell, Dr. Sabeti said, especially without data on the effectiveness of the approach. So she and her colleagues decided to gather some.

“Fundamentally, the paper is about the intersection of kindness and success — how being generous with one’s resources actually is the most effective” strategy, said one of the study’s authors.
“Fundamentally, the paper is about the intersection of kindness and success — how being generous with one’s resources actually is the most effective” strategy, said one of the study’s authors.Pete Kiehart for The New York Times

They developed an epidemiological model to simulate how a virus might spread through a midsize university, like Colorado Mesa University, one of the schools Dr. Sabeti’s team has been advising. (Several C.M.U. officials and researchers are co-authors of the paper.)

Using real-world data from C.M.U., the researchers created a baseline scenario in which 1 percent of people at the school, and 6 percent of those in the surrounding county, were infected by the coronavirus, and the university was testing 12 percent of its members every day. The team assumed that they had a complete list of each university member’s close off-campus contacts, and that if someone tested positive for the virus, they and their contacts would quarantine until they were no longer infectious.

Under these conditions, the researchers found, if the university used all of its tests on its own members, it would have roughly 200 Covid-19 cases after 40 days. But if instead it parceled out some of those tests, using them on community members who were close contacts of students and staff, the number of cases dropped by one-quarter.

“The optimal proportion of tests to use outside the institution on those targeted, first-degree contacts came out to be about 45 percent,” said Ivan Specht, an undergraduate researcher in Dr. Sabeti’s lab and a co-author of the paper. In short, institutions could reduce their caseloads by one-fourth if they used almost half their tests on people just outside their direct membership. That percentage “is remarkably high considering that most institutions use zero percent of their tests outside of themselves,” Mr. Specht noted.

The researchers then tweaked the model’s parameters in various ways: What if the virus were more prevalent? What if students and staff did not report all their contacts? What if they were better about mask-wearing and social distancing? What if the university deployed more tests, or fewer?

Unsurprisingly, the more testing the university did, and the more information it had about its members’ close contacts, the fewer Covid-19 cases there were. But in virtually every scenario, sharing at least some tests with the broader community led to fewer cases than hoarding them.

“The surprising thing is just how robust that finding is in the face of some pretty plausible variations,” said A. David Paltiel, a professor of health policy and management at Yale School of Public Health, who was not involved in the study.

Still, he noted, there were plenty of scenarios that the model didn’t test, and the paper still needs to undergo a thorough peer review.

Its predictions should also be tested in the real world, Dr. O’Connor said: “It needs to be explored and tested head-to-head with other allocation methods.”

But if the findings hold up, it would suggest that schools and other institutions that are trying to reopen safely should think beyond their own walls when they develop testing programs. “Even if your goal is only to protect the students in your care, you will still be doing the maximum to protect those students by taking care of the people in the surrounding community,” Dr. Paltiel said. “That’s a pretty strong argument.”

Some universities are beginning to adopt this outlook. C.M.U. now offers free tests to all of its students’ self-reported contacts, whether or not they are affiliated with the university, and runs a testing site that is open to local residents, said Amy Bronson, a co-chair of the university’s Covid-19 task force and an author of the paper.

And in November, the University of California, Davis, began offering free coronavirus tests to anyone who lives or works in the city. The Healthy Davis Together program, a partnership with the city, has since administered more than 450,000 tests and identified more than 1,000 people with the virus, said Brad Pollock, an epidemiologist at U.C. Davis who directs the project.

“A virus does not respect geographic boundaries,” Dr. Pollock said. “It is ludicrous to think that you can get control of an acute infectious respiratory disease like Covid-19, in a city like Davis that hosts a very large university, without coordinated public health measures that connect both the university and the community.”

There are barriers to the more altruistic approach, including internal political pressure to use testing resources in house and concerns about legal liability. But the researchers hope that their model convinces at least some institutions to rethink their strategy, not only during this epidemic but also in future ones.

“An outbreak is an opportunity to buy a lot of community good will, or to burn a lot of community good will,” Dr. Sabeti said. “We could have spent an entire year building up that relationship between organizations and institutions and their communities. And we would have done all that hard work together, as opposed to everybody turning inward.”

Why It Pays to Think Outside the Box on Coronavirus Tests

Universities and other institutions looking to protect themselves from Covid-19 may benefit from sharing their testing resources with the wider community, a new study suggests.

Last year, when the National Football League decided to stage its season in the midst of the coronavirus pandemic, it went all-in on testing. The league tested all players and personnel before they reported for summer training camp, and continued near-daily testing in the months that followed. Between Aug. 1 and the Super Bowl in early February, the N.F.L. administered almost one million tests to players and staff.

Many other organizations have sought safety in mass testing. The University of Illinois is testing its students, faculty and staff twice a week and has conducted more than 1.6 million tests since July. Major corporations, from Amazon to Tyson Foods, have rolled out extensive testing programs for their own employees.

Now, a new analysis suggests that schools, businesses and other organizations that want to keep themselves safe should think beyond strictly themselves. By dedicating a substantial proportion of their tests to people in the surrounding community, institutions could reduce the number of Covid-19 cases among their members by as much as 25 percent, researchers report in a new paper, which has not yet been published in a scientific journal.

“It’s natural in an outbreak for people to become self-serving, self-focused,” said Dr. Pardis Sabeti, a computational biologist at Harvard University and the Broad Institute who lead the analysis. But, she added, “If you’ve been in enough outbreaks you just understand that testing in a box doesn’t makes sense. These things are communicable, and they’re coming in from the community.”

The study has “really profound implications, especially if others can replicate it, said David O’Connor, a virologist at the University of Wisconsin, Madison, who was not involved in the analysis but reviewed a draft of the paper. As the pandemic enters its second year, he said, “We want to start using more sophisticated modeling and probably economic theory to inform what an optimal testing program would look like.”

Dr. Sabeti is an epidemic veteran, part of teams that responded to an Ebola outbreak in West Africa in 2014 and a mumps outbreak in the Boston area a few years later. When the coronavirus closed down the country last spring, many colleges and universities sought her advice on how to safely reopen.

At a time when testing resources were in short supply, many of these institutions were proposing intensive, expensive testing regimens focused entirely on their own members. Again and again, Dr. Sabeti suggested that universities think more broadly, and allocate some of their tests to people who might be friends, family members or neighbors of their students and employees.

“The metaphor I often used on the calls was to say, ‘You’re in a drought in a place with a lot of forest fires, and you have a shortage of fire alarms,’” she recalled. “‘And if you run out and buy every fire alarm and install it in your own house, you’ll be able to pick up a fire the moment it hits your house, but at that point it’s burning to the ground.’”

Still, convincing university officials to divert precious testing resources away from their own institutions was a hard sell, Dr. Sabeti said, especially without data on the effectiveness of the approach. So she and her colleagues decided to gather some.

“Fundamentally, the paper is about the intersection of kindness and success — how being generous with one’s resources actually is the most effective” strategy, said Kian Sani, one of the study’s authors.
“Fundamentally, the paper is about the intersection of kindness and success — how being generous with one’s resources actually is the most effective” strategy, said Kian Sani, one of the study’s authors.Pete Kiehart for The New York Times

They developed an epidemiological model to simulate how a virus might spread through a midsize university, like Colorado Mesa University, one of the schools Dr. Sabeti’s team has been advising. (Several C.M.U. officials and researchers are co-authors of the paper.)

Using real-world data from C.M.U., the researchers created a baseline scenario in which 1 percent of people at the school, and 6 percent of those in the surrounding county, were infected by the coronavirus, and the university was testing 12 percent of its members every day. The team assumed that they had a complete list of each university member’s close off-campus contacts, and that if someone tested positive for the virus, they and their contacts would quarantine until they were no longer infectious.

Under these conditions, the researchers found, if the university used all of its tests on its own members, it would have roughly 200 Covid-19 cases after 40 days. But if instead it parceled out some of those tests, using them on community members who were close contacts of students and staff, the number of cases dropped by one-quarter.

“The optimal proportion of tests to use outside the institution on those targeted, first-degree contacts came out to be about 45 percent,” said Ivan Specht, an undergraduate researcher in Dr. Sabeti’s lab and a co-author of the paper. In short, institutions could reduce their caseloads by one-fourth if they used almost half their tests on people just outside their direct membership. That percentage “is remarkably high considering that most institutions use zero percent of their tests outside of themselves,” Mr. Specht noted.

The researchers then tweaked the model’s parameters in various ways: What if the virus were more prevalent? What if students and staff did not report all their contacts? What if they were better about mask-wearing and social distancing? What if the university deployed more tests, or fewer?

Unsurprisingly, the more testing the university did, and the more information it had about its members’ close contacts, the fewer Covid-19 cases there were. But in virtually every scenario, sharing at least some tests with the broader community led to fewer cases than hoarding them.

“The surprising thing is just how robust that finding is in the face of some pretty plausible variations,” said A. David Paltiel, a professor of health policy and management at Yale School of Public Health, who was not involved in the study.

Still, he noted, there were plenty of scenarios that the model didn’t test, and the paper still needs to undergo a thorough peer review.

Its predictions should also be tested in the real world, Dr. O’Connor said: “It needs to be explored and tested head-to-head with other allocation methods.”

But if the findings hold up, it would suggest that schools and other institutions that are trying to reopen safely should think beyond their own walls when they develop testing programs. “Even if your goal is only to protect the students in your care, you will still be doing the maximum to protect those students by taking care of the people in the surrounding community,” Dr. Paltiel said. “That’s a pretty strong argument.”

Some universities are beginning to adopt this outlook. C.M.U. now offers free tests to all of its students’ self-reported contacts, whether or not they are affiliated with the university, and runs a testing site that is open to local residents, said Amy Bronson, a co-chair of the university’s Covid-19 task force and an author of the paper.

And in November, the University of California, Davis, began offering free coronavirus tests to anyone who lives or works in the city. The Healthy Davis Together program, a partnership with the city, has since administered more than 450,000 tests and identified more than 1,000 people with the virus, said Brad Pollock, an epidemiologist at U.C. Davis who directs the project.

“A virus does not respect geographic boundaries,” Dr. Pollock said. “It is ludicrous to think that you can get control of an acute infectious respiratory disease like Covid-19, in a city like Davis that hosts a very large university, without coordinated public health measures that connect both the university and the community.”

There are barriers to the more altruistic approach, including internal political pressure to use testing resources in house and concerns about legal liability. But the researchers hope that their model convinces at least some institutions to rethink their strategy, not only during this epidemic but also in future ones.

“An outbreak is an opportunity to buy a lot of community good will, or to burn a lot of community good will,” Dr. Sabeti said. “We could have spent an entire year building up that relationship between organizations and institutions and their communities. And we would have done all that hard work together, as opposed to everybody turning inward.”

Three Feet or Six? Distancing Guideline for Schools Stirs Debate

Some public health officials say it’s time for the C.D.C. to loosen its social distancing guidelines for classrooms, but the idea has detractors.

The Centers for Disease Control and Prevention is clear and consistent in its social distancing recommendation: To reduce the risk of contracting the coronavirus, people should remain at least six feet away from others who are not in their households. The guideline holds whether you are eating in a restaurant, lifting weights at a gym or learning long division in a fourth-grade classroom.

The guideline has been especially consequential for schools, many of which have not fully reopened because they do not have enough space to keep students six feet apart.

Now, spurred by a better understanding of how the virus spreads and a growing concern about the harms of keeping children out of school, some public health experts are calling on the agency to reduce the recommended distance in schools from six feet to three.

“It never struck me that six feet was particularly sensical in the context of mitigation,” said Dr. Ashish Jha, dean of the Brown University School of Public Health. “I wish the C.D.C. would just come out and say this is not a major issue.”

On Sunday, Dr. Anthony S. Fauci, the director of the National Institute of Allergy and Infectious Diseases, said on CNN that the C.D.C. was reviewing the matter.

The idea remains contentious, in part because few studies have directly compared different distancing strategies. But the issue also boils down to a devilishly difficult and often personal question: How safe is safe enough?

“There’s no magic threshold for any distance,” said Dr. Benjamin Linas, a specialist in infectious diseases at Boston University. “There’s risk at six feet, there’s risk at three feet, there’s risk at nine feet. There’s risk always.” He added, “The question is just how much of a risk? And what do you give up in exchange?”

The origins of six feet

The American Academy of Pediatrics recommends three to six feet of social distancing in schools, while the World Health Organization recommends just one meter, or 3.3 feet.
The American Academy of Pediatrics recommends three to six feet of social distancing in schools, while the World Health Organization recommends just one meter, or 3.3 feet.Pete Kiehart for The New York Times

The origin of the six-foot distancing recommendation is something of a mystery. “It’s almost like it was pulled out of thin air,” said Linsey Marr, an expert on viral transmission at Virginia Tech University.

When the virus first emerged, many experts believed that it was transmitted primarily through large respiratory droplets, which are relatively heavy. Old scientific studies, some dating back more than a century, suggested that these droplets tend not to travel more than three to six feet. This observation, as well as an abundance of caution, may have spurred the C.D.C. to make its six foot suggestion, Dr. Marr said.

But that recommendation was not universal. The American Academy of Pediatrics recommends three to six feet of social distancing in schools, but the World Health Organization recommends just one meter, or 3.3 feet.

And over the last year, scientists have learned that respiratory droplets are not the primary mode of coronavirus transmission. Instead, the virus spreads mostly through tiny airborne droplets known as aerosols, which can travel longer distances and flow through rooms in unpredictable ways.

Data also suggests that schools appear to be relatively low-risk environments; children under 10 seem to transmit the virus less readily than adults.

In recent months, there have been hints that six feet of distancing may not be necessary in school settings. Case rates have generally been low even in schools with looser distancing policies. “We know lots of schools have opened up to less than six feet and have not seen big outbreaks,” said Dr. Jha.

In a 2020 analysis of observational studies in a variety of settings, researchers found that physical distancing of at least one meter substantially reduced transmission rates of several different coronaviruses, including the one that causes Covid-19. But they found some evidence to suggest that a two meter guideline “might be more effective.”

“One of the really important data points that has been missing is a direct head-to-head comparison of places that had implemented three feet of distance versus six feet of distance,” said Dr. Elissa Perkins, the director of emergency medicine infectious disease management at Boston University School of Medicine.

A natural experiment

A hand sanitizer station in a Catholic school in Boston in January.Allison Dinner/Reuters

Dr. Perkins and her colleagues recently conducted such a comparison by taking advantage of a natural experiment in Massachusetts. Last summer, the state’s education department issued guidelines recommending three to six feet of distancing in schools that were planning to reopen in the fall. As a result, school policies varied: Some districts imposed strict, six-foot distancing, whereas others required just three. (The state required all staff members, as well as students in second grade and above, to wear masks.)

The researchers found that the social distancing strategy had no statistically significant effect on Covid-19 case rates, the team reported in the journal Clinical Infectious Diseases last week. The study also found that Covid-19 rates were lower in schools than in the surrounding communities.

The authors say the findings provide reassurance that schools can loosen their distancing requirements and still be safe, provided they take other precautions, like enforcing universal mask wearing.

“Masking still appears to be effective,” said lead investigator Dr. Westyn Branch-Elliman, an infectious diseases specialist at the VA Boston Healthcare System. “And so, provided we have universal masking mandates, I think it’s very reasonable to move to a three-foot recommendation.”

Not everyone finds the study so convincing. A. Marm Kilpatrick, an infectious disease researcher at the University of California, Santa Cruz, said that the school-district data was too noisy to draw firm conclusions from. “It doesn’t really allow you to get, I think, an answer that you can feel really confident in,” he said.

The study’s authors acknowledged that they could not rule out the possibility that increased distancing provided a small benefit.

With aerosol transmission, safety generally increases with distance; the farther the aerosols travel, the more they diluted become. “It’s like being close to a smoker,” Dr. Marr said. “The closer you are, the more you’re going to breathe in.”

And distance aside, the more people there are in a room, the higher the odds that one of them will be infected with the coronavirus. A six-foot rule helps reduce that risk, said Donald Milton, an aerosol expert at the University of Maryland: “If people are six feet apart, you can’t pack them in. And so, it’s safer just because it’s less dense.”

Masks and good ventilation do a lot to reduce the risk. With these measures in place, the difference between three and six feet was likely to be relatively small, scientists said. And if Covid-19 is not very prevalent in the surrounding community, the absolute risk of contracting the virus in schools is likely to remain low, as long as these protections are in place.

“We can always do things to reduce our risks further,” Dr. Marr said. “But at some point, you reach diminishing returns, and you have to think about the costs of trying to achieve those additional risk reductions.”

Debate and diminishing risks

“Provided we have universal masking mandates, I think it’s very reasonable to move to a three-foot recommendation,” said one infectious disease specialist.Rosem Morton for The New York Times

Some experts say that a small increase in risk is outweighed by the benefits of fully reopening schools. “Trying to follow the six-foot guideline should not prevent us from getting kids back to school full time with masks, with at least three-foot distancing,” Dr. Marr said.

Others said it was too soon to loosen the C.D.C. guidelines. “Ultimately, I think there could be a place for this changing guidance,” Saskia Popescu, an infectious disease epidemiologist at George Mason University, said in an email. “But it’s not now, when we are struggling to vaccinate people, we’re still seeing over 60,000 cases a day and we’re trying to not reverse the progress we’ve made.”

Even proponents of changing the guideline say that any shift to looser distancing will have to be done carefully, and in combination with other precautionary measures. “If you’re in an area where there’s not a strong tendency to rely on masks, I don’t think it would be wise to extrapolate our data to that environment,” Dr. Perkins said.

Moreover, officials risk muddying the public health messaging if they establish different standards for schools than for other shared spaces. “I’ve evolved on this,” Dr. Linas said. “Last summer I felt like, ‘How are we going to explain to people that it’s six feet everywhere except for schools? That seems not consistent and problematic.’”

But schools are unique, he said. They are relatively controlled environments that can enforce certain safety measures, and they have unique benefits for society. “The benefits of school are different than the benefits of movie theaters or restaurants,” he said. “So I’d be willing to assume a little bit more risk just to keep them open.”

Pandemic Raises Concerns About Childhood Lead Poisoning

Pandemic Raises Concerns About Childhood Lead Poisoning

Lead screenings for children plummeted last spring, and stay-at-home orders may have increased household exposure to the toxic metal.

A worker scraping off lead paint. The C.D.C. estimates that more than 20 million housing units in the United States contain lead-based paint, which was essentially banned in 1978.
A worker scraping off lead paint. The C.D.C. estimates that more than 20 million housing units in the United States contain lead-based paint, which was essentially banned in 1978.Credit…Jamie Hooper/Alamy

  • March 11, 2021, 5:00 a.m. ET

Over the past half-century, public health officials have made enormous progress in protecting American children from lead poisoning and the irreversible neurological damage it can cause. Since the 1970s, the percentage of children with high levels of lead in their blood has plummeted.

But in 2020, a new health threat, the coronavirus, endangered these hard-earned gains.

When Covid-19 cases spiked last spring, lockdowns and day care closures confined young children to their homes, where lead exposure can be particularly high. The growing national emergency also delayed lead-removal efforts and disrupted routine childhood lead screenings, leaving health officials unable to identify and treat many children living in lead-laden homes.

Last month, the Centers for Disease Control and Prevention estimated that in the early months of the pandemic, roughly 10,000 children with elevated levels of lead in their blood may have gone undetected.

“Hundreds of thousands of children have missed their essential tests for lead,” said Joseph Courtney, a senior epidemiologist at the C.D.C.’s lead poisoning prevention and environmental health tracking branch, who conducted the analysis. “And it’s something that has potentially permanent lifetime effects.”

There is no safe level of exposure to lead, which can disrupt neurological and cognitive development, causing learning disabilities, behavioral problems and developmental delays.

The C.D.C. estimates that more than 20 million housing units in the United States contain lead-based paint, which was banned in 1978. When the paint flakes, cracks or peels, the lead mixes with dust, which children can ingest or inhale. Young children, whose brains are still developing, are at particular risk.

“The main route of exposure for most children is lead-contaminated dust, from paint getting on their hands or their toys,” said David Jacobs, chief scientist at the National Center for Healthy Housing. “And then normal child behavior at this age is, everything goes in the mouth.”

For that reason, many states recommend or require that children of certain ages have their blood tested for lead. (Federal guidelines require that all children who are enrolled in Medicaid receive blood lead level tests at ages one and two.) Doctors typically perform these tests as part of a child’s regular checkup.

But when the pandemic hit last March, government officials issued stay-at-home orders, and many medical offices closed. Others started conducting appointments virtually. “You can’t do a blood lead test by telemedicine,” said Dr. Stephanie Yendell, senior epidemiology supervisor at the Minnesota Department of Public Health. “You can’t get a blood sample by video call.”

That month in Minnesota, the number of tests for blood lead level fell to 70 percent of what it had been the previous year, Dr. Yendell said. “And then in April, we bottomed out at 43 percent compared to the year before.”

In New York City, which was hit by an early wave of Covid-19 cases, childhood lead screenings declined by 88 percent last April.

Anecdotal reports of these declines soon made their way to the C.D.C., which asked state and local health officials to share their lead screening data so the agency could conduct a more formal analysis. Thirty-four health departments — representing 32 states, plus New York City and Washington, D.C. — ultimately did so.

Paint is the most common cause of childhood lead poisoning, but lead pipes also pose a threat; the longer that water sits stagnant in such pipes, the more lead leeches into it.
Paint is the most common cause of childhood lead poisoning, but lead pipes also pose a threat; the longer that water sits stagnant in such pipes, the more lead leeches into it.Credit…Julio Cortez/Associated Press

Every one of those departments reported a drop-off in testing last spring, Dr. Courtney and his colleagues found. Over the first five months of 2020, roughly 500,000 fewer children had their blood lead levels tested in these districts compared with the same period of 2019. The decline was especially steep in March, April and May, when testing levels fell 50 percent compared to the previous year.

That kind of decline has no precedent, Dr. Courtney said: “There’s nothing like it before.”

Roughly 2 percent of American children have elevated blood lead levels, Dr. Courtney said. If that percentage holds for the children who missed their screenings last year, it would mean that nearly 10,000 of them had significant lead exposures. “And there were 18 states that we didn’t receive data from that probably would have added to that total,” he noted. “So that’s a conservative estimate.”

There is also reason to suspect that lead poisoning is even more prevalent among the children who missed their blood tests last year, experts said. Children of color, and those who live in low-income neighborhoods, are particularly likely to be exposed to lead. Those same communities have been among the hardest hit by the coronavirus and may have faced the biggest obstacles in receiving pediatric checkups last year.

“We’re afraid that the kids who are being missed are probably the kids at higher risk,” Dr. Courtney said. Some states reported that the dip in lead screenings was especially pronounced among children who were on Medicaid, he added.

For lead-poisoned children, the consequences could be devastating. Although there is no way to reverse lead poisoning, nutritional supplements and educational services can help mitigate the harms. Children who miss their lead screenings may not receive these essential interventions.

Moreover, in many cases, it takes an elevated blood lead level to trigger lead removal or remediation efforts. If you don’t test, you don’t find,” said Dr. Morri Markowitz, director of the lead poisoning treatment and prevention program at the Children’s Hospital at Montefiore, in New York City. “If you don’t find, you don’t intervene, and the kid continues to be exposed, continues potentially to be ingesting lead.” He added: “And then it can progress, and by the time you check, things will have gotten worse.”

Even as lead testing rates were falling last spring, the amount of time that children were spending in their homes, where lead exposure is most likely, was rising. The pandemic, and the financial hardships that accompanied it, may also have prompted some families and property owners to postpone essential building repairs and maintenance tasks.

“I’m very concerned that we potentially may have more children who have been exposed if they’ve been in homes with peeling, chipping paint,” said Dr. Joneigh Khaldun, the chief medical executive for the state of Michigan and chief deputy director for health in the Michigan Department of Health and Human Services. “We just don’t even know it.”

Widespread building closures have created other risks. Although paint is the most common cause of childhood lead poisoning, lead pipes also pose a threat. The longer that water sits stagnant in such pipes, the more lead leeches into it; schools and day care centers that shut down last year could find their water dangerously contaminated when they reopen.

“There’s likely to be high lead levels in some taps,” said Jennifer Hoponick Redmon, a senior environmental health scientist at RTI International, a nonprofit research organization based in North Carolina. “Water needs to be flushed at schools and child care centers — and really, all places that are closed — before people start using the water again for drinking and cooking.”

There is some evidence that lead poisoning rates may have risen slightly last year. Health officials in Massachusetts said they detected a 3 percent increase in the prevalence of lead poisoning among young children between mid-March and mid-August 2020. “While this may seem like a small increase, it is concerning, as we normally see rates of lead poisoning decline each year,” said Jan Sullivan, acting director of the Bureau of Environmental Health at the Massachusetts Department of Public Health.

And in New York City, preliminary data suggests that the share of young children with elevated blood lead levels was essentially flat over the first three-quarters of 2020, after years of steady declines.But not all health departments have found these patterns, and many are still analyzing their data from last year. Of course, if the children who face the biggest lead hazards are the ones who skipped their screenings , a rise in lead poisoning may not show up in the testing data, experts said.

Early evidence suggests that blood lead testing did begin to rebound in the second half of 2020. “But it still fell below the levels of previous years and did not nearly make up for the number of children missed earlier in the year,” Dr. Courtney said.

In Michigan, where childhood lead testing was about one-third lower in 2020 than in 2019, health officials are now trying to make up lost ground. They are organizing mobile lead testing events, to be held across the state, and planning a major media campaign.

“We’re going to put some money behind it, have some commercials and a real intentional focus on making sure people are aware of the risk of lead and that they know how and where to get tested,” said Dr. Khaldun. “We are really focused on making sure we don’t have other unintended consequences of the pandemic.”

Severe Obesity Raises Risk of Covid-19 Hospitalization and Death, Study Finds

Severe Obesity Raises Risk of Covid-19 Hospitalization and Death, Study Finds

A large new study has confirmed an association between obesity and patient outcomes among people who contract the coronavirus.

A Covid-19 patient in the intensive care unit at Sharp Coronado Hospital in Southern California in January.
A Covid-19 patient in the intensive care unit at Sharp Coronado Hospital in Southern California in January.Credit…Etienne Laurent/EPA, via Shutterstock

  • March 8, 2021, 6:56 p.m. ET

Over the past year, many scientific teams around the world have reported that obese people who contract the coronavirus are especially likely to become dangerously ill.

Now, a large new study, of nearly 150,000 adults at more than 200 hospitals across the United States, paints a more detailed picture of the connection between weight and Covid-19 outcomes.

The study, performed by a team of researchers as the Centers for Disease Control and Prevention, has confirmed that obesity significantly increases the risk for hospitalization and death among those who contract the virus. And among those who are obese, the risk increases as a patient’s body mass index, or B.M.I., a ratio of weight to height, increases. Patients with a B.M.I. of 45 or higher, which corresponds to severe obesity, were 33 percent more likely to be hospitalized and 61 percent more likely to die than those who were at a healthy weight, the researchers found.

“The findings of the study highlight the serious clinical public health implications of elevated B.M.I., and they suggest the continued need for intensive management of Covid-19 illness, especially among patients affected by severe obesity,” said the lead author, Lyudmyla Kompaniyets, a health economist at the Division of Nutrition, Physical Activity and Obesity at the C.D.C.

But the relationship between weight and outcomes is nuanced. Covid-19 patients who were underweight were also more likely to be hospitalized than those who were at a healthy weight, although they were not more likely to be admitted to the intensive care unit or to die.

Dr. Kompaniyets and her colleagues used a database of Covid-19 cases to identify 148,494 adults who received a diagnosis of the disease at American hospitals from last March to December. They calculated the B.M.I. of each patient and looked for correlations between B.M.I. and a variety of serious outcomes, including hospitalization, I.C.U. admission, mechanical ventilation and death.

They found that obesity, which is defined as a B.M.I. of 30 or higher, increased the risk of both hospitalization and death. Patients with a B.M.I. of 30 to 34.9 were just 7 percent more likely to be hospitalized and 8 percent more likely to die than people who were at a healthy weight, but the risks increased sharply as B.M.I. rose.

Providing evidence for this kind of “dose response” relationship makes the study particularly compelling, said Dr. Anne Dixon, the director of pulmonary and critical care medicine at the University of Vermont Medical Center, who was not involved in the research. “What it shows is the more severe your obesity, the worse the effect is. And the fact that goes up stepwise with increasing levels of obesity, I think, adds sort of biological plausibility to the relationship between obesity and the outcome.”

The connection between obesity and poor outcomes was strongest among patients under 65, but it held even for older adults. Previous, smaller studies have not found strong links between obesity and severity of Covid-19 in older adults.

“Potentially because they had more power from this large sample size, they’ve demonstrated that obesity remains an important risk factor for death in older adults as well,” said Dr. Michaela R. Anderson, an expert in pulmonary and critical care medicine at Columbia University Medical Center, who was not involved in the study. “It’s a beautifully done study with a massive population.”

Dr. Kompaniyets and her colleagues also documented a linear relationship between B.M.I. and the likelihood of needing mechanical ventilation; the higher the B.M.I., the more likely a patient was to require such intervention, which is invasive and can come with serious complications.

The study also found that patients who were underweight, with a B.M.I. below 18.5, were 20 percent more likely to be hospitalized than those who had a healthy weight. The reasons are not entirely clear, but may stem from the fact that some of these patients were malnourished or frail or had other diseases.

The B.M.I. range associated with the best outcomes, the researchers found, was near the dividing line between what is considered healthy and overweight, consistent with some prior research suggesting that a few extra pounds might help protect people when they contract an infectious disease.

“Exactly why that association exists is currently unknown,” said Dr. Alyson Goodman, a pediatrician and medical epidemiologist at the C.D.C. and a co-author of the study. One possibility is that having a bit of extra fat may provide much needed energy reserves over the course of a long illness.

The findings highlight the importance of carefully managing the care of patients who are severely obese and of ensuring that people who are obese have access to vaccines and other preventive measures.

“This just provides further evidence for the recommendation to vaccinate those with a high B.M.I. as early as feasible,” said Sara Y. Tartof, an infectious disease epidemiologist at the Department of Research & Evaluation at Kaiser Permanente, who was not involved in the study.

Popular Drug Does Not Alleviate Mild Covid-19 Symptoms, Study Finds

Popular Drug Does Not Alleviate Mild Covid-19 Symptoms, Study Finds

Ivermectin, a drug typically used to treat parasitic worms, has been prescribed widely during the coronavirus pandemic, but rigorous data has been lacking.

Ivermectin does not speed recovery in people with mild cases of Covid-19, according to a randomized controlled trial published in the journal JAMA today.
Ivermectin does not speed recovery in people with mild cases of Covid-19, according to a randomized controlled trial published in the journal JAMA today.Credit…Luis Robayo/Agence France-Presse — Getty Images

  • March 4, 2021, 7:13 p.m. ET

Ivermectin, a controversial anti-parasitic drug that has been touted as a potential Covid-19 treatment, does not speed recovery in people with mild cases of the disease, according to a randomized controlled trial published on Thursday in the journal JAMA.

Ivermectin is typically used to treat parasitic worms in both people and animals, but scientific evidence for its efficacy against the coronavirus is thin. Some studies have indicated that the drug can prevent several different viruses from replicating in cells. And last year, researchers in Australia found that high doses of ivermectin suppressed SARS-CoV-2, the virus that causes Covid-19, in cell cultures.

Such findings had spurred use of the drug against Covid-19, especially in Latin America.

“Ivermectin is currently being used widely,” said Dr. Eduardo López-Medina, a doctor and researcher at the Center for Pediatric Infectious Diseases in Cali, Colombia, who led the new trial. “In many countries in the Americas and other parts of the world, it’s part of the national guidelines of treating Covid.”

But the drug has also proved divisive. While some scientists see potential, others suspect that effectively inhibiting the coronavirus may require extremely high, potentially unsafe doses. Health officials have also worried that people desperate for coronavirus treatments might take versions of the drug that have been formulated for pets. (It is commonly used to prevent heartworm in dogs.)

“There’s been a lot of conflicting views on this, sometimes extreme conflicting views,” said Dr. Carlos Chaccour, a researcher at the Barcelona Institute for Global Health who was not involved in the new study. “I think it has become another hydroxychloroquine.”

But neither the proponents nor the critics have had much rigorous data to support their views. There are few well-controlled trials of the drug’s effectiveness against Covid-19, although more are expected in the coming months. And treatment guidelines from the National Institutes of Health note that there is not enough evidence “to recommend either for or against” using the drug in Covid-19 patients.

In the new study, Dr. López-Medina and his colleagues randomly assigned more than 400 people who had recently developed mild Covid-19 symptoms to receive a five-day course of either ivermectin or a placebo. They found that Covid-19 symptoms lasted about 10 days, on average, among people who received the drug, compared with 12 days among those who received the placebo, a statistically insignificant difference.

The new trial adds much-needed clinical data to the debate over using the drug to treat Covid-19, said Dr. Regina Rabinovich, a global health researcher at Harvard’s T.H. Chan School of Public Health, who was not involved in the study.

But she noted that the trial was relatively small and did not answer the most pressing clinical question, whether ivermectin can prevent severe disease or death. “Duration of symptoms may not be the most important either clinical or public health parameter to look at,” she said.

The researchers did find that seven patients in the placebo group deteriorated after enrolling in the trial, compared to four in the ivermectin group, but the numbers were too small to draw a meaningful conclusion.

“There was a small signal there, and it would be interesting to see if that signal that we saw is real or not,” said Dr. López-Medina. “But that would have to be answered in a larger trial.”

Dr. López-Medina also pointed out that the study population was relatively young and healthy, with an average age of 37 and few of the underlying conditions that can make Covid-19 more dangerous.

Bigger trials, which are currently underway, could provide more definitive answers, said Dr. Rabinovich, who noted that she was “totally neutral” on ivermectin’s potential usefulness. “I just want data because there’s such chaos in the field.”

For Some Teens, It’s Been a Year of Anxiety and Trips to the E.R.

For Some Teens, It’s Been a Year of Anxiety and Trips to the E.R.

During the pandemic, suicidal thinking is up. And families find that hospitals can’t handle adolescents in crisis.

Lisa, a mother of three in Asheville, N.C., said that months of virtual classes and social isolation had changed her extroverted 13-year-old son “in profound ways I would never have anticipated.”
Lisa, a mother of three in Asheville, N.C., said that months of virtual classes and social isolation had changed her extroverted 13-year-old son “in profound ways I would never have anticipated.”Credit…Jacob Biba for The New York Times
Benedict Carey

  • Published Feb. 23, 2021Updated Feb. 24, 2021, 5:00 a.m. ET

When the pandemic first hit the Bay Area last spring, Ann thought that her son, a 17-year-old senior, was finally on track to finish high school. He had kicked a heavy marijuana habit and was studying in virtual classes while school was closed.

The first wave of stay-at-home orders shut down his usual routines — sports, playing music with friends. But the stability didn’t last.

“The social isolation since then, over all this time, it just got to him,” said Ann, a consultant living in suburban San Francisco. She, like the other parents in this article, asked that her last name be omitted for privacy and to protect her child. “This is a charming, funny kid, also sensitive and anxious,” she said. “He couldn’t find a job; he couldn’t really go out. And he started using marijuana again, and Xanax.”

The teenager’s frustration finally boiled over this month, when he deliberately cut himself.

“We called 911, and he was taken to the emergency room,” his mother said. “But there they just stitched him up and released him.” The doctors sent him home, she said, “with no support, no therapy, nothing.”

Ann and her son are like many families over the last year. Surveys and statistics show that for young people who are anxious by nature, or feeling emotionally fragile already, the pandemic and its isolation have pushed them to the brink. Rates of suicidal thinking and behavior are up by 25 percent or more from similar periods in 2019, according to a just-published analysis of surveys of young patients coming into the emergency room.

For these teenagers, there aren’t many places to turn. They need help, but it’s hard to come up with a psychiatric diagnosis. They are trying to manage a surprise interruption in their lives, a vague loss. And without a diagnosis, reimbursement for therapy is hard to come by. And that is assuming parents know what kind of help is appropriate, and where to find it.

Finally, when a crisis hits, many of these teenagers end up in the local emergency department — the one place desperate families so often go for help.

Many E.R. departments across the country are now seeing a surge in such cases. Through most of 2020, the proportion of pediatric emergency admissions for mental problems, like panic and anxiety, was up by 24 percent for young children and 31 percent for adolescents compared to the previous year, according to a recent report by the Centers for Disease Control and Prevention.

And the local emergency department is frequently unprepared for the added burden. Workers often are not specially trained to manage behavioral problems, and families don’t have many options for where to go next, leaving many of these pandemic-insecure adolescents in limbo at the E.R.

“This is a national crisis we’re facing,” Dr. Rebecca Baum, a developmental pediatrician in Asheville, N.C. “Kids are having to board in the E.R. for days on end, because there are no psychiatric beds available in their entire state, never mind the hospital. And of course, the child or adolescent is lying there and doesn’t understand what’s happening in the E.R., why they’re having to wait there or where they’re going.”

What Adolescents Are Feeling

Most teenagers and young adults have done fine through this pandemic year, provided that their families have stayed healthy and economically stable. They may be irritable or missing their friends, but their support networks have been enough to get them through the pandemic.

For the young people coming undone, however, pandemic life presents unusual challenges, pediatricians say. Most are temperamentally sensitive and after months of being socially cut off from friends and activities, they have much less control over their moods.

“What parents and children are consistently reporting is an increase in all symptoms — a child who was a little anxious before the pandemic became very anxious over this past year,” said Dr. Adiaha I. A. Spinks-Franklin, an associate professor of pediatrics at the Baylor College of Medicine. It is this prolonged stress, Dr. Spinks-Franklin said, that in time blunts the brain’s ability to manage emotions.

Jean, an artist and mother of two living in Hendersonville, N.C., said that her 17-year-old son was doing fine through last spring. But the months of virtual classes and loss of simple social pleasures — hanging out with friends, playing chess — changed him through the fall months.

“Now, he’s become very reclusive, he has mood swings, he cries a lot,” Jean said. “This giant boy, crying — it’s terrible to see.” The young man has had panic attacks, twice followed by a blackout. During one, he fell and injured his face.

Dr. Adiaha I. A. Spinks-Franklin, an associate professor of pediatrics at the Baylor College of Medicine, says it’s the prolonged stress that blunts the brain’s ability to manage emotions.
Dr. Adiaha I. A. Spinks-Franklin, an associate professor of pediatrics at the Baylor College of Medicine, says it’s the prolonged stress that blunts the brain’s ability to manage emotions.Credit…Brett Deering for The New York Times

Lisa, a mother of three in Asheville, said that the months of virtual classes and relative social isolation had changed her extroverted 13-year-old son “in profound ways I would never have anticipated.”

His grades slipped badly, and he began to withdraw. “Next, he was telling us he couldn’t make himself do the work, that he didn’t want to disappoint us all the time, that he was worthless. Worthless.”

These young people do not necessarily qualify for a psychiatric diagnosis, nor are they “traumatized” in the strict sense of having had a life-threatening experience (or the perception of one.) Rather, they are trying to manage an interruption in their normal development, child psychologists say: a sudden and indefinite suspension of almost every routine and social connection, leaving a deep yet vague sense of loss with no single, distinct source.

The result is grief, but grief without a name or a specific cause, an experience some psychologists call “ambiguous loss.” The concept is usually reserved to describe the experience of immigrants, displaced from everything familiar, who shut down emotionally in a new and strange country. Or to describe disaster survivors, who return to neighborhoods that are hollowed out, transformed.

“Everything that used to be familiar and give structure to their lives, and predictability, and normalcy, is gone,” said Sharon Young, a therapist in Hendersonville. “Kids need all these things even more than adults do, and it’s hard for them to feel emotionally safe when they’re no longer there.”

System Overload

The resulting changes in behavior can seem sudden: A bright sixth-grader is found cutting herself; a sweet-natured sophomore takes a swing at a parent or sibling. Parents, frightened, often don’t know where to go for appropriate help. Many don’t have the resources or knowledge to hire a therapist.

Families that land in the emergency departments of their local hospitals often find that the clinics are poorly equipped to handle these incoming cases. The staff is better trained to manage physical trauma than the mental variety, and patients are often sent right back home, without proper evaluation or support. In severe cases, they may linger in the emergency department for days before a bed can be found elsewhere.

In a recent report, a research team led by the C.D.C. found that less than half of the emergency departments in U.S. hospitals had clear policies in place to handle children with behavior problems. Getting to the bottom of any complex behavior issue can takes days of patient observation, at minimum, psychiatrists say. And many emergency departments do not have the on-hand specialists, dedicated space or off-site resources to help do the job well.

For Jean, diagnosing her son has been complicated. He has since developed irritable bowel syndrome. “He has been losing weight, and started smoking pot due to the boredom,” Jean said. “This is all due to the anxiety.”

Nationwide Children’s Hospital in Columbus, Ohio, has an emergency department that is a decent size for a pediatric hospital, with capacity for 62 children or adolescents. But well before the arrival of the coronavirus, the department was straining to handle increasing numbers of patients with behavior problems.

“This was huge problem pre-pandemic,” said Dr. David Axelson, chief of psychiatry and behavioral health at the hospital. “We were seeing a rise in emergency department visits for mental health problems in kids, specifically for suicidal thinking and self-harm. Our emergency department was overwhelmed with it, having to board kids on the medical unit while waiting for psych beds.”

Last March, to address the crowding, Nationwide Children’s opened a new pavilion, a nine-story facility with 54 dedicated beds for observation and for longer-term stays for those with mental challenges. It has taken the pressure off the hospital’s regular emergency department and greatly improved care, Dr. Axelson said.

Over this pandemic year, with the number of admissions for mental health problems up by some 15 percent over previous years, it is hard to imagine what it would have been like without the additional, devoted behavioral clinic, Dr. Axelson said.

Other hospitals from out of state often call, hoping to place a patient in crisis, but there is simply not enough space. “We have to say no,” Dr. Axelson said.

“We had a shaky system of care in pediatric mental health prior to this pandemic, and now we have all these added stressors on it,” said  Dr. Rebecca Baum, a developmental pediatrician in Asheville, N.C.Credit…Jacob Biba for The New York Times

Dr. Rachel Stanley, the chief of emergency medicine at Nationwide, said that most hospitals have far fewer resources. “I worked at a hospital in Michigan for years, and when these kinds of kids come in, everyone dreaded seeing them, because we didn’t feel like we had the tools to help,” she said. “They have to go into a safe room; they can’t be in a shared area. You have to provide a sitter for the child, a staff person to stay with them all the time to make sure they’re not suicidal or homicidal. It could take hours and hours to get social workers involved, and all this time they’re getting worse.”

Anne, the consultant in the Bay Area, said that her son’s visit to the emergency room this month was his third in the past 18 months, each time for issues related to drug withdrawal. On one visit, he was misdiagnosed with psychosis and sent to a locked county psychiatric ward. “That experience itself — locked for days in a ward, with no one telling him why, or how long he’d be there — was the most traumatic thing he’s experienced,” she said.

Like many other parents, she is now looking after an unstable child and wondering where to go next. A drug rehab program may be needed, as well as regular therapy.

Lisa has hired a therapist for her son, a Zoom session every other week. That seems to have helped, she said, but it is too early to tell. And Jean, for the moment, is hoping the infection risk will diminish soon, so her son can get a safe job.

All three parents have become keen observers of their children, more aware of shifting moods. Listening by itself usually helps relieve distress, therapists say. “Trying to educate parents is a routine part of the job,” said Dr. Robert Duffey, a pediatrician in Hendersonville. “And of course we need these kids back in school, so badly.”

But medical professional say that until the health care system finds a way to equip and support emergency departments for what they have become — the first and sometimes last resort — parents will be left to navigate mostly on their own, leaning on others who have managed similar problems.

“Covid has put our system under a microscope in terms of the things that don’t work,” said Dr. Baum, the pediatrician in Asheville. “We had a shaky system of care in pediatric mental health prior to this pandemic, and now we have all these added stressors on it, all these kids coming in for pandemic-related issues. Hospitals everywhere are scrambling to adjust.”

If you are having thoughts of suicide, call the National Suicide Prevention Lifeline at 1-800-273-8255 (TALK). You can find a list of additional resources at SpeakingOfSuicide.com/resources.

For Some Teens, It’s Been a Year of Anxiety and Trips to the E.R.

For Some Teens, It’s Been a Year of Anxiety and Trips to the E.R.

During the pandemic, suicidal thinking is up. And families find that hospitals can’t handle adolescents in crisis.

Lisa, a mother of three in Asheville, N.C., said that months of virtual classes and social isolation had changed her extroverted 13-year-old son “in profound ways I would never have anticipated.”
Lisa, a mother of three in Asheville, N.C., said that months of virtual classes and social isolation had changed her extroverted 13-year-old son “in profound ways I would never have anticipated.”Credit…Jacob Biba for The New York Times
Benedict Carey

  • Feb. 23, 2021, 3:48 p.m. ET

When the pandemic first hit the Bay Area last spring, Ann thought that her son, a 17-year-old senior, was finally on track to finish high school. He had kicked a heavy marijuana habit and was studying in virtual classes while school was closed.

The first wave of stay-at-home orders shut down his usual routines — sports, playing music with friends. But the stability didn’t last.

“The social isolation since then, over all this time, it just got to him,” said Ann, a consultant living in suburban San Francisco. She, like the other parents in this article, asked that her last name be omitted for privacy and to protect her child. “This is a charming, funny kid, also sensitive and anxious,” she said. “He couldn’t find a job; he couldn’t really go out. And he started using marijuana again, and Xanax.”

The teenager’s frustration finally boiled over this month, when he deliberately cut himself.

“We called 911, and he was taken to the emergency room,” his mother said. “But there they just stitched him up and released him.” The doctors sent him home, she said, “with no support, no therapy, nothing.”

Ann and her son are like many families over the last year. Surveys and statistics show that for young people who are anxious by nature, or feeling emotionally fragile already, the pandemic and its isolation have pushed them to the brink. Rates of suicidal thinking and behavior are up by 25 percent or more from similar periods in 2019, according to a just-published analysis of surveys of young patients coming into the emergency room.

For these teenagers, there aren’t many places to turn. They need help, but it’s hard to come up with a psychiatric diagnosis. They are trying to manage a surprise interruption in their lives, a vague loss. And without a diagnosis, reimbursement for therapy is hard to come by. And that is assuming parents know what kind of help is appropriate, and where to find it.

Finally, when a crisis hits, many of these teenagers end up in the local emergency department — the one place desperate families so often go for help.

Many E.R. departments across the country are now seeing a surge in such cases. Through most of 2020, the proportion of pediatric emergency admissions for mental problems, like panic and anxiety, was up by 24 percent for young children and 31 percent for adolescents compared to the previous year, according to a recent report by the Centers for Disease Control and Prevention.

And the local emergency department is frequently unprepared for the added burden. Workers often are not specially trained to manage behavioral problems, and families don’t have many options for where to go next, leaving many of these pandemic-insecure adolescents in limbo at the E.R.

“This is a national crisis we’re facing,” Dr. Rebecca Baum, a developmental pediatrician in Asheville, N.C. “Kids are having to board in the E.R. for days on end, because there are no psychiatric beds available in their entire state, never mind the hospital. And of course, the child or adolescent is lying there and doesn’t understand what’s happening in the E.R., why they’re having to wait there or where they’re going.”

What Adolescents Are Feeling

Most teenagers and young adults have done fine through this pandemic year, provided that their families have stayed healthy and economically stable. They may be irritable or missing their friends, but their support networks have been enough to get them through the pandemic.

For the young people coming undone, however, pandemic life presents unusual challenges, pediatricians say. Most are temperamentally sensitive and after months of being socially cut off from friends and activities, they have much less control over their moods.

“What parents and children are consistently reporting is an increase in all symptoms — a child who was a little anxious before the pandemic became very anxious over this past year,” said Dr. Adiaha I. A. Spinks-Franklin, an associate professor of pediatrics at the Baylor College of Medicine. It is this prolonged stress, Dr. Spinks-Franklin said, that in time blunts the brain’s ability to manage emotions.

Jean, an artist and mother of two living in Hendersonville, N.C., said that her 17-year-old son was doing fine through last spring. But the months of virtual classes and loss of simple social pleasures — hanging out with friends, playing chess — changed him through the fall months.

“Now, he’s become very reclusive, he has mood swings, he cries a lot,” Jean said. “This giant boy, crying — it’s terrible to see.” The young man has had panic attacks, twice followed by a blackout. During one, he fell and injured his face.

Dr. Adiaha I. A. Spinks-Franklin, an associate professor of pediatrics at the Baylor College of Medicine, says it’s the prolonged stress that blunts the brain’s ability to manage emotions.
Dr. Adiaha I. A. Spinks-Franklin, an associate professor of pediatrics at the Baylor College of Medicine, says it’s the prolonged stress that blunts the brain’s ability to manage emotions.Credit…Brett Deering for The New York Times

Lisa, a mother of three in Asheville, said that the months of virtual classes and relative social isolation had changed her extroverted 13-year-old son “in profound ways I would never have anticipated.”

His grades slipped badly, and he began to withdraw. “Next, he was telling us he couldn’t make himself do the work, that he didn’t want to disappoint us all the time, that he was worthless. Worthless.”

These young people do not necessarily qualify for a psychiatric diagnosis, nor are they “traumatized” in the strict sense of having had a life-threatening experience (or the perception of one.) Rather, they are trying to manage an interruption in their normal development, child psychologists say: a sudden and indefinite suspension of almost every routine and social connection, leaving a deep yet vague sense of loss with no single, distinct source.

The result is grief, but grief without a name or a specific cause, an experience some psychologists call “ambiguous loss.” The concept is usually reserved to describe the experience of immigrants, displaced from everything familiar, who shut down emotionally in a new and strange country. Or to describe disaster survivors, who return to neighborhoods that are hollowed out, transformed.

“Everything that used to be familiar and give structure to their lives, and predictability, and normalcy, is gone,” said Sharon Young, a therapist in Hendersonville. “Kids need all these things even more than adults do, and it’s hard for them to feel emotionally safe when they’re no longer there.”

System Overload

The resulting changes in behavior can seem sudden: A bright sixth-grader is found cutting herself; a sweet-natured sophomore takes a swing at a parent or sibling. Parents, frightened, often don’t know where to go for appropriate help. Many don’t have the resources or knowledge to hire a therapist.

Families that land in the emergency departments of their local hospitals often find that the clinics are poorly equipped to handle these incoming cases. The staff is better trained to manage physical trauma than the mental variety, and patients are often sent right back home, without proper evaluation or support. In severe cases, they may linger in the emergency department for days before a bed can be found elsewhere.

In a recent report, a research team led by the C.D.C. found that less than half of the emergency departments in U.S. hospitals had clear policies in place to handle children with behavior problems. Getting to the bottom of any complex behavior issue can takes days of patient observation, at minimum, psychiatrists say. And many emergency departments do not have the on-hand specialists, dedicated space or off-site resources to help do the job well.

For Jean, diagnosing her son has been complicated. He has since developed irritable bowel syndrome. “He has been losing weight, and started smoking pot due to the boredom,” Jean said. “This is all due to the anxiety.”

Nationwide Children’s Hospital in Columbus, Ohio, has an emergency department that is a decent size for a pediatric hospital, with capacity for 62 children or adolescents. But well before the arrival of the coronavirus, the department was straining to handle increasing numbers of patients with behavior problems.

“This was huge problem pre-pandemic,” said Dr. David Axelson, chief of psychiatry and behavioral health at the hospital. “We were seeing a rise in emergency department visits for mental health problems in kids, specifically for suicidal thinking and self-harm. Our emergency department was overwhelmed with it, having to board kids on the medical unit while waiting for psych beds.”

Last March, to address the crowding, Nationwide Children’s opened a new pavilion, a nine-story facility with 54 dedicated beds for observation and for longer-term stays for those with mental challenges. It has taken the pressure off the hospital’s regular emergency department and greatly improved care, Dr. Axelson said.

Over this pandemic year, with the number of admissions for mental health problems up by some 15 percent over previous years, it is hard to imagine what it would have been like without the additional, devoted behavioral clinic, Dr. Axelson said.

Other hospitals from out of state often call, hoping to place a patient in crisis, but there is simply not enough space. “We have to say no,” Dr. Axelson said.

“We had a shaky system of care in pediatric mental health prior to this pandemic, and now we have all these added stressors on it,” said  Dr. Rebecca Baum, a developmental pediatrician in Asheville, N.C.Credit…Jacob Biba for The New York Times

Dr. Rachel Stanley, the chief of emergency medicine at Nationwide, said that most hospitals have far fewer resources. “I worked at a hospital in Michigan for years, and when these kinds of kids come in, everyone dreaded seeing them, because we didn’t feel like we had the tools to help,” she said. “They have to go into a safe room; they can’t be in a shared area. You have to provide a sitter for the child, a staff person to stay with them all the time to make sure they’re not suicidal or homicidal. It could take hours and hours to get social workers involved, and all this time they’re getting worse.”

Anne, the consultant in the Bay Area, said that her son’s visit to the emergency room this month was his third in the past 18 months, each time for issues related to drug withdrawal. On one visit, he was misdiagnosed with psychosis and sent to a locked county psychiatric ward. “That experience itself — locked for days in a ward, with no one telling him why, or how long he’d be there — was the most traumatic thing he’s experienced,” she said.

Like many other parents, she is now looking after an unstable child and wondering where to go next. A drug rehab program may be needed, as well as regular therapy.

Lisa has hired a therapist for her son, a Zoom session every other week. That seems to have helped, she said, but it is too early to tell. And Jean, for the moment, is hoping the infection risk will diminish soon, so her son can get a safe job.

All three parents have become keen observers of their children, more aware of shifting moods. Listening by itself usually helps relieve distress, therapists say. “Trying to educate parents is a routine part of the job,” said Dr. Robert Duffey, a pediatrician in Hendersonville. “And of course we need these kids back in school, so badly.”

But medical professional say that until the health care system finds a way to equip and support emergency departments for what they have become — the first and sometimes last resort — parents will be left to navigate mostly on their own, leaning on others who have managed similar problems.

“Covid has put our system under a microscope in terms of the things that don’t work,” said Dr. Baum, the pediatrician in Asheville. “We had a shaky system of care in pediatric mental health prior to this pandemic, and now we have all these added stressors on it, all these kids coming in for pandemic-related issues. Hospitals everywhere are scrambling to adjust.”

If you are having thoughts of suicide, call the National Suicide Prevention Lifeline at 1-800-273-8255 (TALK). You can find a list of additional resources at SpeakingOfSuicide.com/resources.

How Meaningful Is Prediabetes for Older Adults?

the new old age

How Meaningful Is Prediabetes for Older Adults?

A new study indicates that the condition might be less of a worry than once believed.

Susan Glickman Weinberg, of Encino, Calif., was told a few years ago during routine tests that she was prediabetic, a diagnosis that puzzled her. “I felt like Patient Zero,” she said. “There were a lot of unknowns.”
Susan Glickman Weinberg, of Encino, Calif., was told a few years ago during routine tests that she was prediabetic, a diagnosis that puzzled her. “I felt like Patient Zero,” she said. “There were a lot of unknowns.”Credit…Jenna Schoenefeld for The New York Times

  • Feb. 23, 2021, 2:30 a.m. ET

A few years ago, routine lab tests showed that Susan Glickman Weinberg, then a 65-year-old clinical social worker in Los Angeles, had a hemoglobin A1C reading of 5.8 percent, barely above normal.

“This is considered prediabetes,” her internist told her. A1C measures how much sugar has been circulating in the bloodstream over time. If her results reached 6 percent — still below the number that defines diabetes, which is 6.5 — her doctor said he would recommend the widely prescribed drug metformin.

“The thought that maybe I’d get diabetes was very upsetting,” recalled Ms. Weinberg, who as a child had heard relatives talking about it as “this mysterious terrible thing.”

She was already taking two blood pressure medications, a statin for cholesterol and an osteoporosis drug. Did she really need another prescription? She worried, too, about reports at the time of tainted imported drugs. She wasn’t even sure what prediabetes meant, or how quickly it might become diabetes.

“I felt like Patient Zero,” she said. “There were a lot of unknowns.”

Now, there are fewer unknowns. A longitudinal study of older adults, published online this month in the journal JAMA Internal Medicine, provides some answers about the very common in-between condition known as prediabetes.

The researchers found that over several years, older people who were supposedly prediabetic were far more likely to have their blood sugar levels return to normal than to progress to diabetes. And they were no more likely to die during the follow-up period than their peers with normal blood sugar.

“In most older adults, prediabetes probably shouldn’t be a priority,” said Elizabeth Selvin, an epidemiologist at the Johns Hopkins Bloomberg School of Public Health in Baltimore and the senior author on the study.

Prediabetes, a condition rarely discussed as recently as 15 years ago, refers to a blood sugar level that is higher than normal but that has not crossed the threshold into diabetes. It is commonly defined by a hemoglobin A1C reading of 5.7 to 6.4 percent or a fasting glucose level of 100 to 125 mg/dL; in midlife, it can portend serious health problems.

A diagnosis of prediabetes means that you are more likely to develop diabetes, and “that leads to downstream illness,” said Dr. Kenneth Lam, a geriatrician at the University of California, San Francisco, and an author of an editorial accompanying the study. “It damages your kidneys, your eyes and your nerves. It causes heart attack and stroke,” he said.

But for an older adult just edging into higher blood sugar levels, it’s a different story. Those fearful consequences take years to develop, and many people in their 70s and 80s will not live long enough to encounter them.

That fact has generated years of debate. Should older people with slightly above-normal blood sugar readings — a frequent occurrence since the pancreas produces less insulin in later life — be taking action, as the American Diabetes Association has urged?

Or does labeling people prediabetic merely “medicalize” a normal part of aging, creating needless anxiety for those already coping with multiple health problems?

Dr. Selvin and her colleagues analyzed the findings of an ongoing national study of cardiovascular risk that began in the 1980s. When 3,412 of the participants showed up for their physicals and lab tests between 2011 and 2013, they had reached ages 71 to 90 and did not have diabetes.

Prediabetes, however, was rampant. Almost three-quarters qualified as prediabetic, based on either their A1C or fasting blood glucose levels.

These findings mirrored a 2016 study pointing out that a popular online risk test created by the Centers for Disease Control and Prevention and the American Diabetes Association, called doihaveprediabetes.org, would deem nearly everyone over 60 as prediabetic.

In 2010, a C.D.C. review reported that 9 to 25 percent of those with an A1C of 5.5 to 6 percent will develop diabetes over five years; so will 25 to 50 percent of those with A1C readings of 6 to 6.5. But those estimates were based on a middle-aged population.

When Dr. Selvin and her team looked at what had actually happened to their older prediabetic cohort five to six years later, only 8 or 9 percent had developed diabetes, depending on the definition used.

A much larger group — 13 percent of those whose A1C level was elevated and 44 percent of those with prediabetic fasting blood glucose — actually saw their readings revert to normal blood sugar levels. (A Swedish study found similar results.)

Sixteen to 19 percent had died, about the same proportion as those without prediabetes.

“We’re not seeing much risk in these individuals,” Dr. Selvin said. “Older adults can have complex health issues. Those that impair quality of life should be the focus, not mildly elevated blood glucose.”

Carol Jacobi, a friend of Ms. Weinberg’s, received a similar diagnosis at around the same time, but did nothing much to reduce her blood sugar.
Carol Jacobi, a friend of Ms. Weinberg’s, received a similar diagnosis at around the same time, but did nothing much to reduce her blood sugar.Credit…Jenna Schoenefeld for The New York Times

Dr. Saeid Shahraz, a health researcher at Tufts Medical Center in Boston and lead author of the 2016 study, praised the new research. “The data is really strong,” he said. “The American Diabetes Association should do something about this.”

It may, said Dr. Robert Gabbay, the A.D.A.’s chief scientific and medical officer. The organization currently recommends “at least annual monitoring” for people with prediabetes, a referral to the lifestyle modification programs shown to decrease health risks and perhaps metformin for those who are obese and under 60.

Now the association’s Professional Practice Committee will review the study, and “it could lead to some adjustments in the way we think about things,” Dr. Gabbay said. Among older people considered prediabetic, “their risk may be smaller than we thought,” he added.

Defenders of the emphasis on treating prediabetes, which is said to afflict one-third of the United States population, point out that first-line treatment involves learning healthy behaviors that more Americans should adopt anyway: weight loss, smoking cessation, exercise and healthy eating.

“I’ve had a number of patients diagnosed with prediabetes, and it’s what motivates them to change,” Dr. Gabbay said. “They know what they should be doing, but they need something to kick them into gear.”

Geriatricians tend to disagree. “It’s unprofessional to mislead people, to motivate them by fear of something that’s not actually true,” Dr. Lam said. “We’re all tired of having things to be afraid of.”

He and Dr. Sei Lee, a coauthor of the editorial accompanying the new study and a fellow geriatrician at the University of California, San Francisco, argue for a case-by-case approach in older adults — especially if a diagnosis of prediabetes will cause their children to berate them over every cookie.

For a patient who is frail and vulnerable, “you’re likely dealing with a host of other problems,” Dr. Lam said. “Don’t worry about this number.”

A very healthy 75-year-old who could live 20 more years faces a more nuanced decision. She may never progress to diabetes; she may also already follow the recommended lifestyle modifications.

Ms. Weinberg, now 69, sought help from a nutritionist, changed her diet to emphasize complex carbohydrates and protein, and began walking more and climbing stairs instead of taking elevators. She shed 10 pounds she didn’t need to lose. Over 18 months, her barely elevated A1C reading fell to 5.6.

Her friend Carol Jacobi, 71, who also lives in Los Angeles, got a similar warning at about the same time. Her A1C was 5.7, the lowest number defined as prediabetic, but her internist immediately prescribed metformin.

Ms. Jacobi, a retired fund-raiser with no family history of diabetes, felt unconcerned. She figured she could lose a little weight, but she had normal blood pressure and an active life that included lots of walking and yoga. After trying the drug for a few months, she stopped.

Now, neither woman has prediabetes. Although Ms. Jacobi did nothing much to reduce her blood sugar, and has gained a few pounds during the pandemic, her A1C has fallen to normal levels, too.

Amid One Pandemic, Students Train for the Next

Amid One Pandemic, Students Train for the Next

Researchers have banded together to find safe, virtual ways to teach the principles of microbiology and epidemiology.

Teresa Bautista, a student at the High School for Environmental Studies in Manhattan, collecting goose dropping samples at Van Cortlandt Park in the Bronx.
Teresa Bautista, a student at the High School for Environmental Studies in Manhattan, collecting goose dropping samples at Van Cortlandt Park in the Bronx.Credit…Christine Marizzi/BioBus
Katherine J. Wu

  • Jan. 21, 2021, 5:00 a.m. ET

On a crisp afternoon in November, Teresa Bautista ventured into Van Cortlandt Park in the Bronx, N.Y., on the lookout for feces. It didn’t take long for Ms. Bautista, 17 — and, to her chagrin, her white Puma shoes — to hit some serious pay dirt.

Speckled all across the park’s grass was the greenish glint of goose droppings, which Ms. Bautista eagerly swabbed and swirled into a tubeful of chemicals. “This was my first time digging into poop,” she said. “It was really fun.”

Ms. Bautista was after more than just bird excrement. Teeming within it, she hoped, were swarms of infectious viruses ready to spill their genetic secrets and, perhaps, help young scientists like her stop future pandemics.

Over the next few months, Ms. Bautista and four other New York area high school students will continue to gather samples from the city’s birds as a part of the Virus Hunters program, hosted by the nonprofit science outreach organization BioBus. Their goal is to catalog the flu viruses that often lurk in urban fowl, some of which might have the potential to someday hop into humans.

The surveillance program, which was developed in partnership with virologists at the Icahn School of Medicine at Mount Sinai, is one of several outreach efforts that have emerged in recent years to equip young scientists with hands-on experience in outbreak preparedness — a quest that has only gained urgency since the new coronavirus started its tear across the globe.

For many months to come, Covid-19 will continue to shutter schools and thwart attempts to gather. The changes have forced educators and researchers to change their teaching tactics. But several groups have met the challenge head on, not merely weathering the pandemic’s inconveniences but transforming them into opportunities for scientific growth.

In Cambridge, Mass., a team of computational biologists designed an outbreak simulation that eerily portended the stealthy spread of the coronavirus and is now fighting the spread of Covid-19 in real-time. In Tucson, Ariz., an immunologist has led an effort to include young, underrepresented scientists in microbiology research, even while the pandemic rages on.

And in New York, where Ms. Bautista is nurturing her love for virology, the effects of these efforts are already starting to take shape. That foraging trip to Van Cortlandt Park, she said, wasn’t just her first experience sampling feces: “It was the first time I actually felt like a scientist.”

Viruses of a feather

The Virus Hunters program was borne of a collaboration among BioBus, a wildlife rehabilitation center called the Wild Bird Fund and a group of researchers led by the Mount Sinai virologist Florian Krammer. Flu viruses are fairly cosmopolitan pathogens that are capable of jumping into a wide range of animals, including birds, and changing their genetic material along the way. Only some of these viruses pose a possible threat to people, Dr. Krammer said. But which ones? Researchers won’t know unless they check.

“There is very little information on influenza circulating in birds in New York City,” Dr. Krammer said. “I wanted to know what’s in my backyard.”

Florian Krammer of the Icahn School of Medicine at Mount Sinai.
Florian Krammer of the Icahn School of Medicine at Mount Sinai.Credit…Brittainy Newman/The New York Times

The project was awarded funding in early 2020, said Christine Marizzi, the chief scientist at BioBus. Weeks later, the coronavirus began to pummel the nation, and the team was forced to shift their plans. But Dr. Marizzi, who has long specialized in community-based research, was undeterred. For the remainder of the school year, the team will train its virus hunters through a mix of virtual lessons, distanced and masked lab work, and sample collection in the field.

It is a welcome distraction for Ms. Bautista, who, like many other students, had to switch to remote learning at her high school in the spring. “When the pandemic hit, I felt really helpless,” she said. “I felt like I couldn’t do anything. So this program is really special to me.”

School of outbreak

A thousand miles south, the students of Sarasota Military Academy Prep, a charter school in Sarasota, Fla., have also had to make some drastic changes since the coronavirus made landfall in the United States. But a select few of them may have entered 2020 a bit more prepared than the rest, because they had experienced a nearly identical epidemic just weeks before.

These were the graduates of Operation Outbreak, a researcher-designed outreach program that has, for the past several years, simulated an annual viral epidemic on the school’s campus. Led by Todd Brown, Sarasota Military Academy Prep’s community outreach director, the program began as a low-tech endeavor that used stickers to mimic the spread of a viral disease. With guidance from a team of researchers led by Pardis Sabeti, a computational biologist at Harvard University, the program quickly morphed into a smartphone app that could ping a virtual virus from student to student with a Bluetooth signal.

Sarasota’s most recent iteration of Operation Outbreak was uncanny in its prescience. Held in December 2019, just weeks before the new coronavirus began its rampage across the globe, the simulation centered on a viral pathogen that moved both swiftly and silently among people, causing spates of flulike symptoms.

The students in each simulation, partitioned into roles in government, public health, medicine, the military and the media, had to scramble to adapt and work together.

Bradford Walker, a junior at the academy, said he felt “really confident” going into the simulation as an eighth grader in 2017. “I was like, ‘We’ll get this together, no problem.’”

But the moment the campus’s outbreak began, “everything became a mess,” Mr. Walker said. Panic ensued; protests flared up; Nerf-gun shots were fired. Media personnel stalked and pestered Mr. Walker, who was acting as a government official. “It was very reminiscent of real life,” he said.

Students with the Sarasota Military Academy Prep “rescued” an ill student to triage as part of the school’s Operation Outbreak program.Credit…Becky Morris

Surrounded by a real pandemic, Mr. Walker often thinks back to his Operation Outbreak days. The program gave him an inkling of what a true viral outbreak might bring, he said. But he’s been unnerved by how wholly unprepared the world was for the coronavirus.

“The coronavirus is a wake-up call,” he said. “We have to be ready for this kind of stuff.”

Operation Outbreak was slated to run several in-person courses in 2020, until an actual pandemic intervened. But Dr. Sabeti and her colleagues have been building online tools, curriculums and games that can bring the lessons of their program to anyone who wants them.

After some careful finagling, the team was also able to engineer a handful of in-person outbreak simulations at college and high school campuses, using an updated version of their smartphone app. One simulation, run over Halloween weekend at Colorado Mesa University, followed a group of more than 350 students as they mingled during their normal routines. Unsurprisingly, an increase in interactions fueled the spread of the fictional virus — the same dynamic that was causing outbreaks of Covid-19 on campus that same semester.

The Operation Outbreak app has since grown more sophisticated. As part of the simulations, users can now toggle their epidemics to include diagnostic tests, masks, vaccines and other public health tools that curb and monitor the spread of infection. Eventually, schools and other organizations might be able to use the simulations as guides as they prepare to reopen for business.

“Beyond being an education tool, it’s a tool to get real-world data,” Dr. Sabeti said. “It’s an exercise in preparing public health teams.”

Expanding science’s reach

Isabel Francisco, left, a doctor of veterinary medcine at the Icahn School of Medicine at Mount Sinai, with Shatoni Bailey, a student at Central Park East High School, participating in BioBus’s virus hunters program.Credit…Christine Marizzi/BioBus

In Arizona, the microbiologist Michael D.L. Johnson has also taken advantage of the pivot to virtual learning prompted by the pandemic. Last summer, he led an effort to enroll 250 students from underrepresented backgrounds in the National Summer Undergraduate Research Program, or NSURP, matching them to more than 150 mentors with expertise in microbiology.

All the projects were remote. But, Dr. Johnson said, that obstacle likely also created opportunities for students who might otherwise have been excluded from science because of geographical or socioeconomic restrictions. And mentors who had old data sets lying around, or heavily computational projects that needed an extra pair of hands, found themselves partnered with eager new collaborators.

“The pandemic has made us adapt,” Dr. Johnson said. “We’re learning that there are some better ways of doing this.”

Some NSURP students even had the opportunity to better understand the coronavirus that had upended their summers. Emy Armanus, now a freshman at the University of California, Irvine, was paired with Suhana Chattopadhyay, an environmental health researcher at the University of Maryland School of Public Health, and spent the summer investigating how the use of nicotine products can worsen cases of Covid-19.

“It definitely made me more knowledgeable about the pandemic,” said Ms. Armanus, who is interested in pursuing a career in medicine. “This program was a great way to discover myself.”

The pandemic has altered just about every aspect of daily life. But Dr. Marizzi of BioBus said students should still feel empowered to engage in scientific discourse — something that sorely needs a new generation of diverse and enthusiastic voices.

For Ms. Bautista, the budding virologist in New York, the Virus Hunters program is bound to leave a lasting impression. Already, she has learned the basics of how viruses infiltrate hosts and how to coax intact genetic material out of cells — and, of course, to never again wear white shoes on a field survey.

[Like the Science Times page on Facebook. | Sign up for the Science Times newsletter.]

Could a Small Test Screen People for Covid-19?

Could a Smell Test Screen People for Covid?

A new modeling study hints that odor-based screens could quash outbreaks. But some experts are skeptical it would work in the real world.

A health worker in Altos de San Lorenzo, a neighborhood outside Buenos Aires, Argentina, administered a smell test last year.
A health worker in Altos de San Lorenzo, a neighborhood outside Buenos Aires, Argentina, administered a smell test last year.Credit…Alejandro Pagni/Agence France-Presse — Getty Images
Katherine J. Wu

  • Jan. 19, 2021, 5:49 p.m. ET

In a perfect world, the entrance to every office, restaurant and school would offer a coronavirus test — one with absolute accuracy, and able to instantly determine who was virus-free and safe to admit and who, positively infected, should be turned away.

That reality does not exist. But as the nation struggles to regain a semblance of normal life amid the uncontrolled spread of the virus, some scientists think that a quick test consisting of little more than a stinky strip of paper might at least get us close.

The test does not look for the virus itself, nor can it diagnose disease. Rather, it screens for one of Covid-19’s trademark signs: the loss of the sense of smell. Since last spring, many researchers have come to recognize the symptom, which is also known as anosmia, as one of the best indicators of an ongoing coronavirus infection, capable of identifying even people who don’t otherwise feel sick.

A smell test cannot flag people who contract the coronavirus and never develop any symptoms at all. But in a study that has not yet been published in a scientific journal, a mathematical model showed that sniff-based tests, if administered sufficiently widely and frequently, might detect enough cases to substantially drive transmission down.

Daniel Larremore, an epidemiologist at the University of Colorado, Boulder, and the study’s lead author, stressed that his team’s work was still purely theoretical. Although some smell tests are already in use in clinical and research settings, the products tend to be expensive and laborious to use and are not widely available. And in the context of the pandemic, there is not yet real-world data to support the effectiveness of smell tests as a frequent screen for the coronavirus. Given the many testing woes that have stymied pandemic control efforts so far, some experts have been doubtful that smell tests could be distributed widely enough, or made sufficiently cheat-proof, to reduce the spread of infection.

“I have been intimately involved in pushing to get loss of smell recognized as a symptom of Covid from the beginning,” said Dr. Claire Hopkins, an ear, nose and throat surgeon at Guy’s and St. Thomas’ Hospitals in the United Kingdom and an author of a recent commentary on the subject in The Lancet. “But I just don’t see any value as a screening test.”

A reliable smell test offers many potential benefits. It could catch far more cases than fever checks, which have largely flopped as screening tools for Covid-19. Studies have found that about 50 to 90 percent of people who test positive for the coronavirus experience some degree of measurable smell loss, a result of the virus wreaking havoc when it invades cells in the airway.

“It’s really like a function of the virus being in the nose at this exact moment,” said Danielle Reed, the associate director of the Monell Chemical Senses Center in Philadelphia. “It complements so much of the information you get from other tests.” Last month, Dr. Reed and her colleagues at Monell posted a study, which has not yet been published in a scientific journal, describing a rapid smell test that might be able to screen for Covid-19.

In contrast, only a minority of people with Covid-19 end up spiking a temperature. Fevers also tend to be fleeting, while anosmia can linger for many days.

A coronavirus testing site in Los Angeles. Smell tests, unlike P.C.R. and antigen tests, would not diagnose the disease nor look for the virus directly.
A coronavirus testing site in Los Angeles. Smell tests, unlike P.C.R. and antigen tests, would not diagnose the disease nor look for the virus directly.Credit…Kendrick Brinson for The New York Times

A smell test could also come with an appealingly low price tag, perhaps as low as 50 cents per card, said Derek Toomre, a cell biologist at Yale University and an author on Dr. Larremore’s paper. Dr. Toomre hopes that his version will fit the bill. The test, the U-Smell-It test, is a small smorgasbord of scratch-and-sniff scents arrayed on paper cards. People taking the test pick away at wells of smells, inhale and punch their guess into a smartphone app, shooting to correctly guess at least three of the five odors. Different cards contain different combinations of scents, so there is no answer key to memorize.

He estimated that the test could be taken in less than a minute. It is also a manufacturer’s dream, he said: A single printer “could produce 50 million of these tests per day.” Numbers like that, he argued, could make an enormous dent in a country hampered by widespread lack of access to tests that look directly for pieces of the coronavirus.

In their study, Dr. Larremore, Dr. Toomre and their collaborator Roy Parker, a biochemist at the University of Colorado, Boulder, modeled such a scenario using computational tools. Administered daily or almost daily, a smell screen that caught at least 50 percent of new infections was able to quash outbreaks nearly as well as a more accurate, slower laboratory test given just once a week.

Such tests, Dr. Larremore said, could work as a point-of-entry screen on college campuses or in offices, perhaps in combination with a rapid virus test. There might even be a place for them in the home, if researchers can find a way to minimize misuse.

“I think this is spot on,” said Dr. Carol Yan, an ear, nose and throat specialist at the University of California, San Diego. “Testing people repeatedly is going to be a valuable portion of this.”

Dr. Toomre is now seeking an emergency use authorization for the U-Smell-It from the Food and Drug Administration, and has partnered with a number of groups in Europe and elsewhere to trial the test under real-world conditions.

Translating theory into practice, however, will come with many challenges. Smell tests that can reliably identify people who have the coronavirus, while excluding people who are sick with something else, are not yet widely available. (Dr. Hopkins pointed to a couple of smell tests, developed before the pandemic, that cost about $30 each and remain in limited supply.) Should they ever be rolled out in bulk, they would inevitably miss some infected people and, unlike tests that look for the actual virus, could never diagnose disease on their own.

And smell loss, like fever, is not exclusive to Covid-19. Other infections can blunt a person’s sense of smell. So can allergies, nasal congestion from the common cold, or simply the process of aging. About 80 percent of people over the age of 75 have some degree of smell loss. Some people are born anosmic.

Moreover, in many cases of Covid-19, smell loss can linger long after the virus is gone and people are no longer contagious — a complication that could land some people in a post-Covid purgatory if they are forced to rely on smell screens to resume activity, Dr. Yan said.

There are also many ways to design a smell-based screen. Odors linked to foods that are popular in some countries but not others, such as bubble gum or licorice, might skew test results for some individuals. People who have grown up in highly urban areas might not readily recognize scents from nature, like pine or fresh-cut grass.

Smell also is not a binary sense, strictly on or off. Dr. Reed advocated a step in which test takers rate the intensity of a test’s odors — an acknowledgment that the coronavirus can drastically reduce the sense of smell but not eliminate it.

But the more complicated the test, the more difficult it would be to manufacture and deploy speedily. And no test, even a perfectly designed one, would function with 100 percent accuracy.

Dr. Ameet Kini, a pathologist at Loyola University Medical Center, pointed out that smell tests would also not be free of the problems associated with other types of tests, such as poor compliance or a refusal to isolate.

Smell screens are “probably better than nothing,” Dr. Kini said. “But no test is going to stop the pandemic in its tracks unless it’s combined with other measures.”

Could a Smell Test Screen People for Covid?

Could a Smell Test Screen People for Covid?

A new modeling study hints that odor-based screens could quash outbreaks. But some experts are skeptical it would work in the real world.

A health worker in Altos de San Lorenzo, a neighborhood outside Buenos Aires, Argentina, administered a smell test last year.
A health worker in Altos de San Lorenzo, a neighborhood outside Buenos Aires, Argentina, administered a smell test last year.Credit…Alejandro Pagni/Agence France-Presse — Getty Images
Katherine J. Wu

  • Jan. 19, 2021, 5:49 p.m. ET

In a perfect world, the entrance to every office, restaurant and school would offer a coronavirus test — one with absolute accuracy, and able to instantly determine who was virus-free and safe to admit and who, positively infected, should be turned away.

That reality does not exist. But as the nation struggles to regain a semblance of normal life amid the uncontrolled spread of the virus, some scientists think that a quick test consisting of little more than a stinky strip of paper might at least get us close.

The test does not look for the virus itself, nor can it diagnose disease. Rather, it screens for one of Covid-19’s trademark signs: the loss of the sense of smell. Since last spring, many researchers have come to recognize the symptom, which is also known as anosmia, as one of the best indicators of an ongoing coronavirus infection, capable of identifying even people who don’t otherwise feel sick.

A smell test cannot flag people who contract the coronavirus and never develop any symptoms at all. But in a study that has not yet been published in a scientific journal, a mathematical model showed that sniff-based tests, if administered sufficiently widely and frequently, might detect enough cases to substantially drive transmission down.

Daniel Larremore, an epidemiologist at the University of Colorado, Boulder, and the study’s lead author, stressed that his team’s work was still purely theoretical. Although some smell tests are already in use in clinical and research settings, the products tend to be expensive and laborious to use and are not widely available. And in the context of the pandemic, there is not yet real-world data to support the effectiveness of smell tests as a frequent screen for the coronavirus. Given the many testing woes that have stymied pandemic control efforts so far, some experts have been doubtful that smell tests could be distributed widely enough, or made sufficiently cheat-proof, to reduce the spread of infection.

“I have been intimately involved in pushing to get loss of smell recognized as a symptom of Covid from the beginning,” said Dr. Claire Hopkins, an ear, nose and throat surgeon at Guy’s and St. Thomas’ Hospitals in the United Kingdom and an author of a recent commentary on the subject in The Lancet. “But I just don’t see any value as a screening test.”

A reliable smell test offers many potential benefits. It could catch far more cases than fever checks, which have largely flopped as screening tools for Covid-19. Studies have found that about 50 to 90 percent of people who test positive for the coronavirus experience some degree of measurable smell loss, a result of the virus wreaking havoc when it invades cells in the airway.

“It’s really like a function of the virus being in the nose at this exact moment,” said Danielle Reed, the associate director of the Monell Chemical Senses Center in Philadelphia. “It complements so much of the information you get from other tests.” Last month, Dr. Reed and her colleagues at Monell posted a study, which has not yet been published in a scientific journal, describing a rapid smell test that might be able to screen for Covid-19.

In contrast, only a minority of people with Covid-19 end up spiking a temperature. Fevers also tend to be fleeting, while anosmia can linger for many days.

A coronavirus testing site in Los Angeles. Smell tests, unlike P.C.R. and antigen tests, would not diagnose the disease nor look for the virus directly.
A coronavirus testing site in Los Angeles. Smell tests, unlike P.C.R. and antigen tests, would not diagnose the disease nor look for the virus directly.Credit…Kendrick Brinson for The New York Times

A smell test could also come with an appealingly low price tag, perhaps as low as 50 cents per card, said Derek Toomre, a cell biologist at Yale University and an author on Dr. Larremore’s paper. Dr. Toomre hopes that his version will fit the bill. The test, the U-Smell-It test, is a small smorgasbord of scratch-and-sniff scents arrayed on paper cards. People taking the test pick away at wells of smells, inhale and punch their guess into a smartphone app, shooting to correctly guess at least three of the five odors. Different cards contain different combinations of scents, so there is no answer key to memorize.

He estimated that the test could be taken in less than a minute. It is also a manufacturer’s dream, he said: A single printer “could produce 50 million of these tests per day.” Numbers like that, he argued, could make an enormous dent in a country hampered by widespread lack of access to tests that look directly for pieces of the coronavirus.

In their study, Dr. Larremore, Dr. Toomre and their collaborator Roy Parker, a biochemist at the University of Colorado, Boulder, modeled such a scenario using computational tools. Administered daily or almost daily, a smell screen that caught at least 50 percent of new infections was able to quash outbreaks nearly as well as a more accurate, slower laboratory test given just once a week.

Such tests, Dr. Larremore said, could work as a point-of-entry screen on college campuses or in offices, perhaps in combination with a rapid virus test. There might even be a place for them in the home, if researchers can find a way to minimize misuse.

“I think this is spot on,” said Dr. Carol Yan, an ear, nose and throat specialist at the University of California, San Diego. “Testing people repeatedly is going to be a valuable portion of this.”

Dr. Toomre is now seeking an emergency use authorization for the U-Smell-It from the Food and Drug Administration, and has partnered with a number of groups in Europe and elsewhere to trial the test under real-world conditions.

Translating theory into practice, however, will come with many challenges. Smell tests that can reliably identify people who have the coronavirus, while excluding people who are sick with something else, are not yet widely available. (Dr. Hopkins pointed to a couple of smell tests, developed before the pandemic, that cost about $30 each and remain in limited supply.) Should they ever be rolled out in bulk, they would inevitably miss some infected people and, unlike tests that look for the actual virus, could never diagnose disease on their own.

And smell loss, like fever, is not exclusive to Covid-19. Other infections can blunt a person’s sense of smell. So can allergies, nasal congestion from the common cold, or simply the process of aging. About 80 percent of people over the age of 75 have some degree of smell loss. Some people are born anosmic.

Moreover, in many cases of Covid-19, smell loss can linger long after the virus is gone and people are no longer contagious — a complication that could land some people in a post-Covid purgatory if they are forced to rely on smell screens to resume activity, Dr. Yan said.

There are also many ways to design a smell-based screen. Odors linked to foods that are popular in some countries but not others, such as bubble gum or licorice, might skew test results for some individuals. People who have grown up in highly urban areas might not readily recognize scents from nature, like pine or fresh-cut grass.

Smell also is not a binary sense, strictly on or off. Dr. Reed advocated a step in which test takers rate the intensity of a test’s odors — an acknowledgment that the coronavirus can drastically reduce the sense of smell but not eliminate it.

But the more complicated the test, the more difficult it would be to manufacture and deploy speedily. And no test, even a perfectly designed one, would function with 100 percent accuracy.

Dr. Ameet Kini, a pathologist at Loyola University Medical Center, pointed out that smell tests would also not be free of the problems associated with other types of tests, such as poor compliance or a refusal to isolate.

Smell screens are “probably better than nothing,” Dr. Kini said. “But no test is going to stop the pandemic in its tracks unless it’s combined with other measures.”

How to (Literally) Drive the Coronavirus Away

How to (Literally) Drive the Coronavirus Away

What’s the transmission risk inside a car? An airflow study offers some insight for passengers and drivers alike.

Although cars don’t carry enough people to host a traditional superspreader event, they are small, sealed spaces that can still carry the risk of Covid-19 transmission.
Although cars don’t carry enough people to host a traditional superspreader event, they are small, sealed spaces that can still carry the risk of Covid-19 transmission.Credit…Matt Rourke/Associated Press

  • Jan. 16, 2021, 5:00 a.m. ET

Over the past year, as the health authorities have tried to curb the Covid-19 pandemic, researchers have trained their scientific attention on a variety of potentially risky environments: places where large groups of people gather and the novel coronavirus has ample opportunity to spread. They have swabbed surfaces on cruise ships, tracked case numbers in gyms, sampled ventilation units in hospitals, mapped seating arrangements in restaurants and modeled boarding procedures in airplanes.

They have paid less attention to another everyday environment: the car. A typical car, of course, does not carry nearly enough people to host a traditional super-spreader event. But cars come with risks of their own; they are small, tightly sealed spaces that make social distancing impossible and trap the tiny, airborne particles, or aerosols, that can transmit the coronavirus.

“Even if you’re wearing a face covering, you still get tiny aerosols that are released every time you breathe,” said Varghese Mathai, a physicist at the University of Massachusetts, Amherst. “And if it’s a confined cabin, then you keep releasing these tiny particles, and they naturally would build up over time.”

In a new study, Dr. Mathai and three colleagues at Brown University — Asimanshu Das, Jeffrey Bailey and Kenneth Breuer — used computer simulations to map how virus-laden airborne particles might flow through the inside of a car. Their results, published in early January in Science Advances, suggest that opening certain windows can create air currents that could help keep both riders and drivers safe from infectious diseases like Covid-19.

To conduct the study, the research team employed what are known as computational fluid dynamic simulations. Engineers commonly use these kinds of computer simulations, which model how gases or liquids move, to create racecars with lower drag, for instance, or airplanes with better lift.

The team simulated a car loosely based on a Toyota Prius driving at 50 miles per hour, with two occupants: a driver in the front left seat and a single passenger in the back right, a seating arrangement that is common in taxis and ride shares and that maximizes social distancing. In their initial analysis, the researchers found that the way the air flows around the outside of the moving car creates a pressure gradient inside the car, with the air pressure in the front slightly lower than the air pressure in the back. As a result, air circulating inside the cabin tends to flow from the back of the car to the front.

A diagram showing air circulation in a car with the front right and rear left windows open. A pressure gradient causes the air to generally flow from back to front in the car.
A diagram showing air circulation in a car with the front right and rear left windows open. A pressure gradient causes the air to generally flow from back to front in the car.Credit…Mathai et al., Science Advances 2021

Next, they modeled the interior air flow — and the movement of simulated aerosols — when different combinations of windows were open or closed. (The air-conditioning was on in all scenarios.) Unsurprisingly, they found that the ventilation rate was lowest when all four windows were closed. In this scenario, roughly 8 to 10 percent of aerosols exhaled by one of the car’s occupants could reach the other person, the simulation suggested. When all the windows were completely open, on the other hand, ventilation rates soared, and the influx of fresh air flushed many of the airborne particles out of the car; just 0.2 to 2 percent of the simulated aerosols traveled between driver and passenger.

The results jibe with public health guidelines that recommend opening windows to reduce the spread of the novel coronavirus in enclosed spaces. “It’s essentially bringing the outdoors inside, and we know that the risk outdoors is very low,” said Joseph Allen, a ventilation expert at the Harvard T.H. Chan School of Public Health. In an op-ed last year, he highlighted the danger that cars could pose for coronavirus transmission, and the potential benefits of opening the windows. “When you have that much turnover of air, the residence time, or how much time the aerosols stay inside the cabin, is very short,” Dr. Allen said

Because it’s not always practical to have all the windows wide open, especially in the depths of winter, Dr. Mathai and his colleagues also modeled several other options. They found that while the most intuitive-seeming solution — having the driver and the passenger each roll down their own windows — was better than keeping all the windows closed, an even better strategy was to open the windows that are opposite each occupant. That configuration allows fresh air to flow in through the back left window and out through the front right window and helps create a barrier between the driver and the passenger.

“It’s like an air curtain,” Dr. Mathai said. “It flushes out all the air that’s released by the passenger, and it also creates a strong wind region in between the driver and the passenger.”

Richard Corsi, an air quality expert at Portland State University, praised the new study. “It’s pretty sophisticated, what they did,” he said, although he cautioned that changing the number of passengers in the car or the driving speed could affect the results.

Dr. Corsi, a co-author of the op-ed with Dr. Allen last year, has since developed his own model of the inhalation of coronavirus aerosols in various situations. His results, which have not yet been published, suggest that a 20-minute car ride with someone who is emitting infectious coronavirus particles can be much riskier than sharing a classroom or a restaurant with that person for more than an hour.

“The focus has been on superspreader events” because they involve a lot of people, he said. “But I think what sometimes people miss is that superspreader events are started by somebody who’s infected who comes to that event, and we don’t speak often enough about where that person got infected.”

In a follow-up study, which has not yet been published, Dr. Mathai found that opening the windows halfway seemed to provide about the same benefit as opening them fully, while cracking them just one-quarter of the way open was less effective.

Dr. Mathai said that the general findings would most likely hold for many four-door, five-seat cars, not just the Prius. “For minivans and pickups, I would still say that opening all windows or opening at least two windows can be beneficial,” he said. “Beyond that, I would be extrapolating too much.”

Ride-sharing companies should be encouraging this research, Dr. Mathai said. He sent a copy of his study to Uber and Lyft, he said, but has not received a response.

[Like the Science Times page on Facebook. | Sign up for the Science Times newsletter.]

One Mask Is Good. Would Two Would Be Better?

One Mask Is Good. Would Two Would Be Better?

Health experts double down on their advice for slowing the spread of the coronavirus.

A double-mask wearer in New York City in April.
A double-mask wearer in New York City in April.Credit…Kena Betancur/Getty Images
Katherine J. Wu

  • Jan. 12, 2021, 12:51 p.m. ET

Football coaches do it. President-elects do it. Even science-savvy senators do it. As cases of the coronavirus continue to surge on a global scale, some of the nation’s most prominent people have begun to double up on masks — a move that researchers say is increasingly being backed up by data.

Double-masking isn’t necessary for everyone. But for people with thin or flimsy face coverings, “if you combine multiple layers, you start achieving pretty high efficiencies” of blocking viruses from exiting and entering the airway, said Linsey Marr, an expert in virus transmission at Virginia Tech and an author on a recent commentary laying out the science behind mask-wearing.

Of course, there’s a trade-off: At some point, “we run the risk of making it too hard to breathe,” she said. But there is plenty of breathing room before mask-wearing approaches that extreme.

A year into the Covid-19 pandemic, the world looks very different. More than 90 million confirmed coronavirus infections have been documented worldwide, leaving millions dead and countless others with lingering symptoms, amid ongoing economic hardships and shuttered schools and businesses. New variants of the virus have emerged, carrying genetic changes that appear to enhance their ability to spread from person to person.

And while several vaccines have now cleared regulatory hurdles, the rollout of injections has been sputtering and slow — and there is not yet definitive evidence to show that shots will have a substantial impact on how fast, and from whom, the virus will spread.

Through all that change, researchers have held the line on masks. “Americans will not need to be wearing masks forever,” said Dr. Monica Gandhi, an infectious disease physician at the University of California, San Francisco, and an author on the new commentary. But for now, they will need to stay on, delivering protection both to mask-wearers and to the people around them.

The arguments for masking span several fields of science, including epidemiology and physics. A bevy of observational studies have suggested that widespread mask-wearing can curb infections and deaths on an impressive scale, in settings as small as hair salons and at the level of entire countries. One study, which tracked state policies mandating face coverings in public, found that known Covid cases waxed and waned in near-lockstep with mask-wearing rules. Another, which followed coronavirus infections among health care workers in Boston, noted a drastic drop in the number of positive test results after masks became a universal fixture among staff. And a study in Beijing found that face masks were 79 percent effective at blocking transmission from infected people to their close contacts.

Recent work by researchers like Dr. Marr is now pinning down the basis of these links on a microscopic scale. The science, she said, is fairly intuitive: Respiratory viruses like the coronavirus, which move between people in blobs of spittle and spray, need a clear conduit to enter the airway, which is crowded with the types of cells the viruses infect. Masks that cloak the nose and mouth inhibit that invasion.

The point is not to make a mask airtight, Dr. Marr said. Instead, the fibers that comprise masks create a haphazard obstacle course through which air — and any infectious cargo — must navigate.

“The air has to follow this tortuous path,” Dr. Marr said. “The big things it’s carrying are not going to be able to follow those twists and turns.”

Experiments testing the extent to which masks can waylay inbound and outbound spray have shown that even fairly basic materials, like cloth coverings and surgical masks, can be at least 50 percent effective in either direction.

Several studies have reaffirmed the notion that masks seem to be better at guarding people around the mask-wearer than mask-wearers themselves. “That’s because you’re stopping it right at the source,” Dr. Marr said. But, motivated by recent research, the Centers for Disease Control and Prevention has noted that there are big benefits for those who don masks as well.

Masks awaiting disinfecting at the Battelle N95 decontamination site in Somerville, Mass.
Masks awaiting disinfecting at the Battelle N95 decontamination site in Somerville, Mass.Credit…Michael Dwyer/Associated Press

The best masks remain N95s, which are designed with ultrahigh filtration efficiency. But they remain in short supply for health workers, who need them to safely treat patients.

Layering two less specialized masks on top of each other can provide comparable protection. Dr. Marr recommended wearing face-hugging cloth masks over surgical masks, which tend to be made with more filter-friendly materials but fit more loosely. An alternative is to wear a cloth mask with a pocket that can be stuffed with filter material, like the kind found in vacuum bags.

But wearing more than two masks, or layering up on masks that are already very good at filtering, will quickly bring diminishing returns and make it much harder to breathe normally.

Other tweaks can enhance a mask’s fit, such as ties that secure the fabric around the back of the head, instead of relying on ear loops that allow masks to hang and gape. Nose bridges, which can help the top of a mask to fit more snugly, offer a protective boost as well.

Achieving superb fit and filtration “is really simple,” Dr. Gandhi said. “It doesn’t need to involve anything fancy.”

No mask is perfect, and wearing one does not obviate other public health measures like physical distancing and good hygiene. “We have to be honest that the best response is one that requires multiple interventions,” said Jennifer Nuzzo, a public health expert at Johns Hopkins University.

Mask-wearing remains uncommon in some parts of the country, in part because of politicization of the practice. But experts noted that model behavior by the nation’s leaders might help to turn the tide. In December, President-elect Joseph R. Biden Jr. implored Americans to wear masks for his first 100 days in office, and said he would make doing so a requirement in federal buildings and on planes, trains and buses that cross state lines.

A large review on the evidence behind masking, published this month in the journal PNAS, concluded that masks are a key tool for reducing community transmission, and is “most effective at reducing spread of the virus when compliance is high.”

Part of the messaging might also require more empathy, open communication and vocal acknowledgment that “people don’t enjoy wearing masks,” Dr. Nuzzo said. Without more patience and compassion, simply doubling down on restrictions to “fix” poor compliance will backfire: “No policy is going to work if no one is going to adhere.”

[Like the Science Times page on Facebook. | Sign up for the Science Times newsletter.]

A Colonoscopy Alternative Comes Home

A Colonoscopy Alternative Comes Home

An at-home test for colon cancer is as reliable as the traditional screening, health experts say, and more agreeable.

Credit…Karlotta Freier

  • Jan. 11, 2021, 1:40 p.m. ET

Most Americans who are due for a colon cancer screening will receive a postcard or a call — or prompting during a doctor’s visit — to remind them that it’s time to schedule a colonoscopy.

But at big health care systems like Kaiser Permanente or the federal Veterans Health Administration, the process has changed. Patients who should be screened regularly (age 50 to 75) and who are of average risk, get a letter telling them about a home test kit arriving by mail.

It’s a FIT, which stands for fecal immunochemical test. The small cardboard mailer contains equipment and instructions for taking a stool sample and returning the test to a lab, to detect microscopic amounts of blood. A week or so later, the results show up on an online patient portal.

Five to 6 percent of patients will have a positive test and need to schedule a follow-up colonoscopy. But the great majority are finished with colon cancer screening for the year — no uncomfortable prep, no need to skip work or find someone to drive them home after anesthesia, no colonoscopy.

Last spring, when the coronavirus pandemic closed many medical facilities and postponed nonemergency procedures, this approach suddenly looked even more desirable.

“We know that from March to May, colon cancer screenings fell by about 90 percent,” said Dr. Rachel Issaka, a gastroenterologist at the University of Washington and the Fred Hutchinson Cancer Research Center. Although testing has resumed, she said, “we’re still not back to where we were.”

Yet colon cancer represents the third-highest cause of cancer deaths, after lung cancer and, tied for second place, breast and prostate cancer. Unlike those, colon cancer can be prevented with early detection.

With many older adults trying to avoid hospitals and surgical centers, even as their risk of colon cancer rises with age, an at-home test provides an alternative to colonoscopy — one that is both safer, with a lower risk of complications and Covid-19 exposure, and does as good a job.

“If your doctor tells you a colonoscopy is better, that’s not accurate,” said Dr. Alex Krist, chairman of the U.S. Preventive Services Task Force, an independent expert panel that reviews evidence and issues recommendations. “The data show the tests are equally effective at saving lives.”

The Task Force is updating its guidelines for colon cancer screening and this year will likely recommend lowering the age at which it should begin, to 45. But the recommendations on the upper end will remain unchanged: Based on strong evidence, adults up to age 75 should be screened regularly.

Beyond that age, the disadvantages begin to mount. The Task Force says the benefit of screening 76- to 85-year-olds is small, and that the decision should be an individual one, reached in consultation with a doctor.

Colon cancer develops slowly, explained Dr. James Goodwin, a geriatrician and researcher at the University of Texas Medical Branch in Galveston. Patients at older ages, who typically contend with several other diseases, may not live long enough to benefit. “You cause more harm than good,” Dr. Goodwin said.

The advice to stop screening isn’t always popular with patients. “People don’t like to hear about not living very long,” he said. But with colonoscopy, he noted, “you go through an unpleasant experience — or an unpleasant experience followed by an unpleasant diagnosis and unpleasant treatment — for something that, if you’d never known about it, wouldn’t cause you harm.”

Even if a test eventually finds colon cancer, surgery plus chemotherapy, the standard treatment, could itself endanger a frail older person. “I would be heavily biased against anyone getting a screening, of any sort, over age 80,” Dr. Goodwin said.

Although Americans still rely mostly on colonoscopy, his research has shown that for many older people, that test is overused, either because of the patients’ ages or because they are tested too frequently.

Yet screening is simultaneously underused. In 2018, according to the Centers for Disease Control and Prevention, only about 70 percent of adults were up-to-date on colorectal cancer testing. About one-fifth of those 65 to 75 had not been screened as recommended. Among those 50 to 65, where lack of Medicare or other insurance probably contributed, only about 63 percent were appropriately screened.

The Task Force has found several kinds of screening tests effective, but the ones used most for people at average risk are colonoscopy, at a recommended 10-year interval, or FIT annually.

A newer entry, an at-home test sold under the brand name Cologuard that detects blood and cancer biomarkers in stool, may be used every three years, but a study found it to be less effective than most other methods and far more expensive than FIT.

When screening is recommended, how does FIT stack up against colonoscopy?

Higher-risk patients — including those who have had colon cancer or parents or siblings with colon cancer, those with inflammatory bowel disorders like Crohn’s disease, and those who have had abnormal previous tests, including multiple or large polyps — should seek out a colonoscopy, often on an accelerated schedule. The procedure involves inserting a viewing instrument through the anus to directly visualize an anesthetized patient’s colon.

A colonoscopy offers one distinct advantage: if the gastroenterologist spots polyps, growths that over time could become cancerous (although most don’t), these can be removed immediately. “You’re preventing cancer, snipping out the things that could lead to cancer,” Dr. Goodwin said. After a negative colonoscopy, patients don’t need another for a decade.

But the procedure’s complications increase with age, although they remain low; the most serious, a perforated colon, requires hospitalization. Cleaning out the bowel on the day before the procedure, in preparation, is disruptive and disagreeable, and Dr. Goodwin notes that older patients sometimes experience cycles of diarrhea and constipation for weeks afterward.

Rural residents may find traveling to a facility difficult. The use of anesthesia means that every patient needs someone to drive or escort them home afterward. The prospect of spending two to four hours in a facility, even one using rigorous safety measures, will cause some older adults to postpone testing because of Covid-19 fears.

The FIT, which is far more widely used in other countries, avoids many of those difficulties. A marked improvement over earlier at-home stool tests, it requires a sample from one day instead of samples from three, and imposes no food or drug restrictions. A positive result still calls for a colonoscopy, but the great majority of patients avoid that outcome.

Why do so many Americans still undergo colonoscopies, then? “There’s a large financial incentive for people who do colonoscopies to do colonoscopies,” Dr. Goodwin said, so patients may not hear much about the alternatives.

“Many of my own patients are surprised to learn that there’s another way,” said Dr. Krist, also a family physician at Virginia Commonwealth University. “As they age, they want less invasive methods” and may be happy to switch.

Wider adoption of FIT could also save patients and insurers, notably Medicare, a boatload. The home test, which is available through several manufacturers, generally costs less than $20; a colonoscopy can easily exceed $1,000.

Moreover, with personalized messages to patients and follow-up reminders to return the kit, FIT use can result in more people being screened. That could prove important when the Preventive Services Task Force lowers the recommended age to 45, which would add 22 million Americans to the list of people advised to undergo colon cancer screening. Their needs, plus a backlog of patients who postponed tests during the pandemic, could swamp gastroenterology practices.

“If a provider doesn’t bring up” the possibility of an at-home test, Dr. Issaka said, “patients should feel empowered to ask about it.” Colon cancer screenings, of any type, “are considered non-urgent,” she said. “But they’re not optional.”

[Like the Science Times page on Facebook. | Sign up for the Science Times newsletter.]

One 18-Hour Flight, Four Coronavirus Infections

One 18-Hour Flight, Four Coronavirus Infections

An outbreak aboard a September flight from Qatar to New Zealand offers researchers, and airlines, an opportunity to study in-transit contagion.

A masked passenger on a flight out of Kansas City, Mo., last year. The study of a largely empty flight last fall suggests that airlines will need to further tighten precautions on flights.
A masked passenger on a flight out of Kansas City, Mo., last year. The study of a largely empty flight last fall suggests that airlines will need to further tighten precautions on flights.Credit…Charlie Riedel/Associated Press
Benedict Carey

  • Jan. 7, 2021, 5:50 p.m. ET

The millions of airline passengers who traveled over the holidays experienced firsthand the unsettling uncertainties that come with flying during a pandemic. The anxious glances. The awkward semi-distancing. The haphazard mask etiquette, and the absence of regular service.

In an effort to reassure, the airlines have updated and adjusted their requirements for travelers, with patchwork results. Some airlines work to maintain social distance, both at the gate and at boarding; others are less vigilant. Mask-wearing is dependent on passenger compliance, and not predictable; nor, increasingly, is flight capacity, which can range from 20 percent to nearly full.

Given the variables, infectious disease specialists have had a hard time determining the risks of flying. But a study published on Wednesday provides some clarity.

After an 18-hour flight from Dubai landed in Auckland, New Zealand, in September, local health authorities discovered evidence of an outbreak that most likely occurred during the trip. Using seat maps and genetic analysis, the new study determined that one passenger initiated a chain of infection that spread to four others en route.

Previous research on apparent in-flight outbreaks focused on flights that occurred last spring, when few travelers wore masks, planes were running near capacity and the value of preventive measures was not broadly understood. The new report, of a largely empty flight in the fall, details what can happen even when airlines and passengers are aware and more cautious about the risks.

The findings deliver a clear warning to both airlines and passengers, experts said.

“The key message here is that you have to have multiple layers of prevention — requiring testing before boarding, social distancing on the flight, and masks,” said Dr. Abraar Karan, an internal medicine physician at Brigham and Women’s Hospital and Harvard Medical School who was not part of the study team. “Those things all went wrong in different ways on this flight, and if they’d just tested properly, this wouldn’t have happened.”

The new infections were detected after the plane landed in New Zealand; the country requires incoming travelers to quarantine for 14 days before entering the community. The analysis, led by researchers at the New Zealand Ministry of Health, found that seven of the 86 passengers on board tested positive during their quarantine and that at least four were newly infected on the flight. The aircraft, a Boeing 777-300ER, with a capacity of nearly 400 passengers, was only one-quarter full.

A diagram from the study shows the seating arrangement of the seven passengers who tested positive. The open circles represent passengers who tested negative for the coronavirus after the flight. All other seats shown remained empty.
A diagram from the study shows the seating arrangement of the seven passengers who tested positive. The open circles represent passengers who tested negative for the coronavirus after the flight. All other seats shown remained empty.Credit…Centers for Disease Control and Prevention

These seven passengers came from five countries, and they were seated within four rows of one another for the 18-hour duration of the flight. Two acknowledged that they did not wear masks, and the airline did not require mask-wearing in the lobby before boarding. Nor did it require preflight testing, although five of the seven passengers who later tested positive had taken a test, and received a negative result, in the days before boarding.

The versions of the coronavirus that all seven carried were virtually identical genetically — strongly suggesting that one person among them initiated the outbreak. That person, whom the report calls Passenger A, had in fact tested negative four or five days before boarding, the researchers found.

“Four or five days is a long time,” Dr. Kamar said. “You should be asking for results of rapid tests done hours before the flight, ideally.”

Even restrictive “Covid-free” flights, international bookings that require a negative result to board, give people a day or two before departure to get a test.

The findings are not definitive, cautioned the authors, led by Dr. Tara Swadi, an adviser with New Zealand’s Health Ministry. But results “underscore the value of considering all international passengers arriving in New Zealand as being potentially infected, even if pre-departure testing was undertaken, social distancing and spacing were followed, and personal protective equipment was used in-flight,” the researchers concluded.

Previous studies of infection risk during air travel did not clearly quantify the risk, and onboard air filtration systems are thought to reduce the infection risk among passengers even when a flight includes one or more infected people. But at least two recent reports strongly suggest that in-flight outbreaks are a risk: one of a flight from Boston to Hong Kong in March; the other of a flight from London to Hanoi, Vietnam, also in March.

On the Hong Kong flight, the analysis suggested that two passengers who boarded in Boston infected two flight attendants. On the Hanoi flight, researchers found that 12 of 16 people who later tested positive were sitting in business class, and that proximity to the infectious person strongly predicted infection risk.

Airline policies vary widely, depending on the flight and the carrier. During the first months of the pandemic, most U.S. airlines had a policy of blocking off seats, or allowing passengers to reschedule if a flight was near 70 percent full. But by the holidays those policies were largely phased out, said Scott Mayerowitz, executive editor at The Points Guy, a website that covers the industry.

All carriers have a mask policy, for passengers and crew — although passengers are not always compliant.

“Even before the pandemic, passengers weren’t always the best at following rules on airplanes,” Mr. Mayerowitz said. “Something about air travel brings out the worse in people, whether it’s fighting over reclined seats, or overhead bin space, or wearing a mask properly.”

Temperature checks are uncommon and are less than reliable as an indicator of infectiousness. And coronavirus tests are not needed for boarding, at least on domestic flights. Some international flights are “Covid tested”: to fly from New York to Rome on Alitalia, for example, passengers must have received a negative test result within 48 hours of boarding. They are tested again on arrival in Rome.

Dr. Kamar said that, unless all preventive measures are in place, there will be some risk of infection on almost any flight.

“It is surprising and not surprising, on an 18-hour flight, that an outbreak would occur,” Dr. Kamar said. “It’s more than likely that more than just those two people took off their mask at some point,” and every such lapse increases the likelihood of spread.

[Like the Science Times page on Facebook. | Sign up for the Science Times newsletter.]

Covid-19: How Much Herd Immunity is Enough?

Scientists initially estimated that 60 to 70 percent of the population needed to acquire resistance to the coronavirus to banish it. Now Dr. Anthony Fauci and others are quietly shifting that number upward.

How Much Herd Immunity Is Enough?

How Much Herd Immunity Is Enough?

Scientists initially estimated that 60 to 70 percent of the population needed to acquire resistance to the coronavirus to banish it. Now Dr. Anthony Fauci and others are quietly shifting that number upward.

Dr. Anthony S. Fauci in March. “We really don’t know what the real number is,” he said recently.
Dr. Anthony S. Fauci in March. “We really don’t know what the real number is,” he said recently.Credit…Doug Mills/The New York Times
Donald G. McNeil Jr.

  • Dec. 24, 2020, 5:00 a.m. ET

At what point does a country achieve herd immunity? What portion of the population must acquire resistance to the coronavirus, either through infection or vaccination, in order for the disease to fade away and life to return to normal?

Since the start of the pandemic, the figure that many epidemiologists have offered has been 60 to 70 percent. That range is still cited by the World Health Organization and is often repeated during discussions of the future course of the disease.

Although it is impossible to know with certainty what the limit will be until we reach it and transmission stops, having a good estimate is important: It gives Americans a sense of when we can hope to breathe freely again.

Recently, a figure to whom millions of Americans look for guidance — Dr. Anthony S. Fauci, an adviser to both the Trump administration and the incoming Biden administration — has begun incrementally raising his herd-immunity estimate.

In the pandemic’s early days, Dr. Fauci tended to cite the same 60 to 70 percent estimate that most experts did. About a month ago, he began saying “70, 75 percent” in television interviews. And last week, in an interview with CNBC News, he said “75, 80, 85 percent” and “75 to 80-plus percent.”

In a telephone interview the next day, Dr. Fauci acknowledged that he had slowly but deliberately been moving the goal posts. He is doing so, he said, partly based on new science, and partly on his gut feeling that the country is finally ready to hear what he really thinks.

Hard as it may be to hear, he said, he believes that it may take close to 90 percent immunity to bring the virus to a halt — almost as much as is needed to stop a measles outbreak.

Asked about Dr. Fauci’s conclusions, prominent epidemiologists said that he might be proven right. The early range of 60 to 70 percent was almost undoubtedly too low, they said, and the virus is becoming more transmissible, so it will take greater herd immunity to stop it.

Dr. Fauci said that weeks ago, he had hesitated to publicly raise his estimate because many Americans seemed hesitant about vaccines, which they would need to accept almost universally in order for the country to achieve herd immunity.

Now that some polls are showing that many more Americans are ready, even eager, for vaccines, he said he felt he could deliver the tough message that the return to normal might take longer than anticipated.

“When polls said only about half of all Americans would take a vaccine, I was saying herd immunity would take 70 to 75 percent,” Dr. Fauci said. “Then, when newer surveys said 60 percent or more would take it, I thought, ‘I can nudge this up a bit,’ so I went to 80, 85.

“We need to have some humility here,” he added. “We really don’t know what the real number is. I think the real range is somewhere between 70 to 90 percent. But, I’m not going to say 90 percent.”

Doing so might be discouraging to Americans, he said, because he is not sure there will be enough voluntary acceptance of vaccines to reach that goal. Although sentiments about vaccines in polls have bounced up and down this year, several current ones suggest that about 20 percent of Americans say they are unwilling to accept any vaccine.

Also, Dr. Fauci noted, a herd-immunity figure at 90 percent or above is in the range of the infectiousness of measles.

“I’d bet my house that Covid isn’t as contagious as measles,” he said.

Measles is thought to be the world’s most contagious disease; it can linger in the air for hours or drift through vents to infect people in other rooms. In some studies of outbreaks in crowded military barracks and student dormitories, it has kept transmitting until more than 95 percent of all residents are infected.

Interviews with epidemiologists regarding the degree of herd immunity needed to defeat the coronavirus produced a range of estimates, some of which were in line with Dr. Fauci’s. They also came with a warning: All answers are merely “guesstimates.”

“You tell me what numbers to put in my equations, and I’ll give you the answer,” said Marc Lipsitch, an epidemiologist at Harvard’s T.H. Chan School of Public Health. “But you can’t tell me the numbers, because nobody knows them.”

The only truly accurate measures of herd immunity are done in actual herds and come from studying animal viruses like rinderpest and foot-and-mouth disease, said Dr. David M. Morens, Dr. Fauci’s senior adviser on epidemiology at the National Institute of Allergy and Infectious Diseases.

When cattle are penned in corrals, it is easy to measure how fast a disease spreads from one animal to another, he said. Humans move around, so studying disease spread among them is far harder.

The original assumption that it would take 60 to 70 percent immunity to stop the disease was based on early data from China and Italy, health experts noted.

Epidemiologists watching how fast cases doubled in those outbreaks calculated that the virus’s reproduction number, or R0 — how many new victims each carrier infected — was about 3. So two out of three potential victims would have to become immune before each carrier infected fewer than one. When each carrier infects fewer than one new victim, the outbreak slowly dies out.

Two out of three is 66.7 percent, which established the range of 60 to 70 percent for herd immunity.

The French aircraft carrier Charles de Gaulle arriving in the port of Toulon in April, carrying infected sailors.
The French aircraft carrier Charles de Gaulle arriving in the port of Toulon in April, carrying infected sailors.Credit… Marine Nationale, via Agence France-Presse — Getty Images

Reinforcing that notion was a study conducted by the French military on the crew of the aircraft carrier Charles de Gaulle, which had an outbreak in late March, said Dr. Christopher J.L. Murray, director of the University of Washington’s Institute for Health Metrics and Evaluation.

The study found that 1,064 of the 1,568 sailors aboard, or about 68 percent, had tested positive for the virus.

But the carrier returned to port while the outbreak was still in progress, and the crew went into quarantine, so it was unclear whether the virus was finished infecting new sailors even after 68 percent had caught it.

Also, outbreaks aboard ships are poor models for those on land because infections move much faster in the close quarters of a vessel than in a free-roaming civilian population, said Dr. Natalie E. Dean, a biostatistician at the University of Florida.

More important, the early estimates from Wuhan and Italy were later revised upward, Dr. Lipsitch noted, once Chinese scientists realized they had undercounted the number of victims of the first wave. It took about two months to be certain that there were many asymptomatic people who had also spread the virus.

It also became clearer later that “superspreader events,” in which one person infects dozens or even hundreds of others, played a large role in spreading Covid-19. Such events, in “normal” populations — in which no one wears masks and everyone attends events like parties, basketball tournaments or Broadway shows — can push the reproduction number upward to 4, 5 or even 6, experts said. Consequently, those scenarios call for higher herd immunity; for example, at an R0 of 5, more than four out of five people, or 80 percent, must be immune to slow down the virus.

Further complicating matters, there is a growing consensus among scientists that the virus itself is becoming more transmissible. A variant “Italian strain” with the mutation known as D614G has spread much faster than the original Wuhan variant. A newly identified mutation, sometimes called N501Y, that may make the virus even more infectious has recently appeared in Britain, South Africa and elsewhere.

The more transmissible a pathogen, the more people must become immune in order to stop it.

Dr. Morens and Dr. Lipsitch agreed with Dr. Fauci that the level of herd immunity needed to stop Covid-19 could be 85 percent or higher. “But that’s a guesstimate,” Dr. Lipsitch emphasized.

“Tony’s reading the tea leaves,” Dr. Morens said.

The Centers for Disease Control and Prevention offers no herd immunity estimate, saying on its website that “experts do not know.”

Although W.H.O. scientists still sometimes cite the older 60 to 70 percent estimate, Dr. Katherine O’Brien, the agency’s director of immunization, said that she now thought that range was too low. She declined to estimate what the correct higher one might be.

“We’d be leaning against very thin reeds if we tried to say what level of vaccine coverage would be needed to achieve it,” she said. “We should say we just don’t know. And it won’t be a world or even national number. It will depend on what community you live in.”

Dr. Dean noted that to stop transmission in a crowded city like New York, more people would have to achieve immunity than would be necessary in a less crowded place like Montana.

Even if Dr. Fauci is right and it will take 85 or even 90 percent herd immunity to completely stop coronavirus transmission, Dr. Lipsitch said, “we can still defang the virus sooner than that.”

He added: “We don’t have to have zero transmission in order to have a decent society. We have lots of diseases, like flu, transmitting all the time, and we don’t shut down society for that. If we can vaccinate almost all the people who are most at risk of severe outcomes, then this would become a milder disease.”

[Like the Science Times page on Facebook. | Sign up for the Science Times newsletter.]

Hearing Aids Could Use Some Help

the new old age

Hearing Aids Could Use Some Help

The vital medical devices could be inexpensive and available over the counter. But efforts have stalled under the F.D.A.

Credit…
Isabel Seliger

  • Dec. 14, 2020, 11:56 a.m. ET

By now, we were supposed to be swiftly approaching the day when we could walk into a CVS or Walgreens, a Best Buy or Walmart, and walk out with a pair of quality, affordable hearing aids approved by the Food and Drug Administration.

Hearing aids, a widely needed but dauntingly expensive investment, cost on average $4,700 a pair. (Most people need two.) So in 2017, Congress passed legislation allowing the devices to be sold directly to consumers, without a prescription from an audiologist. The next step was for the F.D.A. to issue draft regulations to establish safety and effectiveness benchmarks for these over-the-counter devices.

Its deadline: August 2020. A public comment period would follow, and then — right about now — the agency would be preparing its final rule, to take effect in May 2021. So by next summer, people with what is known as “perceived mild to moderate hearing loss” might need to spend only one-quarter of today’s price or less, maybe far less. And then we could have turned down the TV volume and stopped making dinner reservations for 5:30 p.m., when restaurants are mostly empty and conversations are still audible.

“These regulations are going to help a lot of people,” said Dr. Vinay Rathi, an otolaryngologist at Massachusetts Eye and Ear. “There could be great potential for innovation.”

So, where are the new rules? This long-sought alternative to the current state of hearing aid services has been delayed, perhaps one more victim of the pandemic.

Of course, the agency has other crucial matters to address just now. Although the office charged with hearing aid regulations is not the one assessing Covid-19 vaccines, an F.D.A. spokesman said via email that it was dealing with “an unprecedented volume of emergency use authorizations” for diagnostics, ventilators and personal protective equipment.

Nevertheless, “issuing the proposed rule remains a priority and we are working expeditiously to do so,” the spokesman added, providing no timetable for when that might happen.

It’s a major undertaking. The F.D.A. has never established such requirements for hearing aids, because ever since it last issued regulations, in 1977, only state-licensed providers have been allowed to prescribe and sell them — and have been presumed able to safeguard wearers. Providers and manufacturers have also kept prices high by combining testing, fitting and sales into one costly package, a practice the new law was designed to disrupt.

No other country has regulated over-the-counter hearing aids, according to Dr. Frank Lin, an otolaryngologist and director of the Cochlear Center for Hearing and Public Health at Johns Hopkins University. “We’ll be the first,” he said. “There are no performance requirements. There’s no precedent.”

But, Dr. Rathi said, “it’s not like the F.D.A. put everything else on hold.” He pointed to an array of regulations issued last month by the agency, including guidance on cross-labeling oncology medications and rules on impurities in animal drugs. “They’re still going about a lot of their regular business.”

Recently he and a colleague wrote an editorial in The New England Journal of Medicine that questioned the delay, under a pointed title, “Deafening Silence from the F.D.A.”

Senator Elizabeth Warren, Democrat of Massachusetts and Senator Chuck Grassley, Republican of Iowa, who were among the sponsors of the bipartisan 2017 law, wrote to the F.D.A. commissioner last month urging action. They noted that “despite the pandemic, hearing loss continues to be a problem for millions of Americans.” In fact, masks and distancing create greater hearing difficulties.

One-quarter of Americans in their 60s and nearly two-thirds of those over 70 have hearing loss. Its damaging consequences can include social isolation, an increased risk of falls and much higher rates of dementia.

Yet a recent analysis of federal data shows that despite modest increases, in 2018 only about 18.5 percent of Medicare beneficiaries over 70 owned and used hearing aids.

Usage was lower among women than men and far lower among Black beneficiaries than white ones; the proportion of low-income seniors using hearing aids actually declined to 10.8 percent in 2018 from 12.4 percent in 2011.

Stigma explains some of that aversion. Hearing aids can feel like “constant reminders of aging,” said Kevin Franck, director of audiology at Massachusetts Eye and Ear and an author of the New England Journal editorial. “We have people who come in who want to hide them.”

The inconvenience of multiple visits to an audiologist or technician for testing, fitting and adjustment probably also plays a role.

But expense constitutes a formidable barrier. Traditional Medicare covers testing but not hardware or other services. (It does cover cochlear implants, for those whose hearing loss grows too severe for hearing aids.) Many Medicare Advantage plans provide some hearing coverage, but beneficiaries still wind up paying 79 percent of the cost out of pocket.

“It’s the No. 1 question we get,” said Barbara Kelley, executive director of the Hearing Loss Association of America. “‘I can’t afford hearing aids and Medicare doesn’t cover them. What do I do?’”

Advocates plan to keep lobbying Congress for Medicare coverage for hearing services and aids, included in the expansive bill H.R.3 that passed the House of Representatives last year but never came to a Senate vote.

In the meantime, over-the-counter devices retailing for several hundred dollars could make hearing aids broadly more affordable, for people or — one day, perhaps — for Medicare.

They could also solve another consumer problem, Dr. Lin added. Manufacturers can legally sell PSAPs — personal sound-amplification products that resemble hearing aids — as long as they don’t advertise them as a remedy for hearing loss. Their quality varies drastically.

The Hopkins team has been testing whether trained community health workers could help low-income seniors improve their hearing. (A pilot study indicates they can.) Their research protocol uses an effective PSAP from Sound World Solutions that retails for about $700 a pair.

But, Dr. Lin said, “most of what you see out there — ‘$50 miracle device!’ — is complete garbage. People can’t tell which to trust.”

Once federal requirements are set for over-the-counter hearing aids, however, manufacturers of quality PSAPs can apply for approval. “All the other PSAPs will go by the wayside,” Dr. Lin said. If their labels say they’re not approved by the F.D.A., “nobody will buy them, and they shouldn’t.”

Eyeing a vast and underserved market, consumer electronics companies (said to include Apple and Samsung) are standing by, along with start-ups. “There’s a lot of venture capital funding for hearing technology, once the barriers come down,” Dr. Rathi said.

Bose acted early, receiving F.D.A. clearance in 2018 for its Hearphone, which the buyer could tune with a smartphone app. But without the new rule, state restrictions would have prevented national sales, so Bose didn’t market it.

The company is working on a new over-the-counter product, however. “We’re cautiously optimistic that 2021 will be the year,” said Brian Maguire, director of the Bose Hear group.

Once the F.D.A. acts and companies and retailers ramp up, expect new products and advertisements to pop up in stores and online. “We’ll have a bit of a Wild West period,” Ms. Kelley said. “People are going to be confused. They’re going to need a lot of information.”

At that point, audiologists will no longer serve as exclusive gatekeepers to hearing aids. But they can still render important services: testing, education and counseling, adjusting devices — even if clients bought them elsewhere.

“Wearing something comfortably in your ear all day, day after day, is a challenge,” Dr. Franck said. “You want it customized. If you hear echoes or feedback, audiologists know a lot about those issues.”

But the country has only about 18,000 audiologists, Ms. Kelley pointed out. Particularly in rural areas, people with hearing loss might need to drive hours to find one.

But a supermarket? A big box store? A pharmacy? A website? Almost everyone can get to one of those.

[Like the Science Times page on Facebook. | Sign up for the Science Times newsletter.]

Fears of a ‘Twindemic’ Recede as Flu Lies Low

Fears of a ‘Twindemic’ Recede as Flu Lies Low

Despite early worries, flu patients are not competing with Covid-19 patients for ventilators, and the threat of dueling outbreaks may be waning.

A free flu shot administered at Comerica Park in Detroit, Mich., last month.
A free flu shot administered at Comerica Park in Detroit, Mich., last month.Credit…Seth Herald/Agence France-Presse — Getty Images
Donald G. McNeil Jr.

  • Dec. 13, 2020, 5:00 a.m. ET

Despite the horrifying surge of Covid-19 cases and deaths in the United States right now, one bit of good news is emerging this winter: It looks unlikely that the country will endure a “twindemic” of both flu and the coronavirus at the same time.

That comes as a profound relief to public health officials who predicted as far back as April that thousands of flu victims with pneumonia could pour into hospitals this winter, competing with equally desperate Covid-19 pneumonia victims for scarce ventilators.

“Overall flu activity is low, and lower than we usually see at this time of year,” said Dr. Daniel B. Jernigan, director of the influenza division of the Centers for Disease Control and Prevention. “I don’t think we can definitively say there will be no twindemic; I’ve been working with flu for a long time, and I’ve been burned. But flu is atypically low.”

Since September, the C.D.C. “FluView” — its weekly report on influenza surveillance — has shown all 50 states in shades of green and chartreuse, indicating “minimal” or “low” flu activity. Normally by December, at least some states are painted in oranges and reds for “moderate” and “high.”

(For one puzzling week in November, Iowa stood out in dark burgundy, indicating “very high” flu levels. But that turned out to be a reporting error, Dr. Jernigan said.)

Of 232,452 swabs from across the country that have been tested for flu, only 496, or 0.2 percent, have come up positive.

That has buoyed the spirits of flu experts.

Dr. William Schaffner, medical director for the National Foundation for Infectious Diseases, which promotes flu shots, said he was recently on a telephone discussion with other preventive medicine specialists. “Everybody was in quiet awe about how low flu is,” he said. “Somebody said: ‘Shh, don’t talk about it. The virus will hear us.’”

Flu numbers are likely to remain low for many more weeks, predicted Kinsa Health, a company that uses cellphone-connected thermometers and historical databases to forecast flu trends.

“Going forward, we don’t expect influenza-like illness to go high,” said Inder Singh, Kinsa’s founder and chief executive. “It looks like the twindemic isn’t going to happen.”

7% of population sick with flu

2019–20

6

5

2017–18

4

2018–19

3

2

2020–21

flu season

1

Forecast

Sept.

Oct.

Nov.

Dec.

Jan.

Feb.

7% of population sick with flu

2019–20

6

5

2017–18

4

2018–19

3

2

2020–21

flu season

1

Forecast

Oct.

Nov.

Dec.

Jan.

Feb.

7% of population sick with flu

2019–20

6

5

2017–18

4

2018–19

3

2

2020–21

flu season

1

Forecast

Nov.

Dec.

Jan.

Feb.

By The New York Times | Source: Kinsa

A combination of factors is responsible for the remarkably quiet flu season, experts said.

In the Southern Hemisphere, where winter stretches from June through August, widespread mask-wearing, rigorous lockdowns and other precautions against Covid-19 transmission drove flu down to record-low levels. Southern Hemisphere countries help “reseed” influenza viruses in the Northern Hemisphere each year, Dr. Jernigan said.

Also, to keep Covid-19 out, New Zealand and Australia have closed their borders either to all noncitizens or to Americans, so there has been very little air traffic from those Southern Hemisphere countries.

In the United States, the cancellation of large indoor gatherings, closings of schools and use of masks to prevent coronavirus transmission have also driven down levels of all respiratory diseases, including influenza.

In addition, Dr. Jernigan said, a “phenomenal number” of flu shots were manufactured and shipped to pharmacies, hospitals and doctors’ office in August, a month earlier than usual.

As of late November, 188 million doses had been shipped; the old record was 175 million doses shipped last year. Spot shortages were quickly reported in some cities, so experts assumed that large numbers of Americans took them.

However, there is not yet enough data to confirm that assumption. According to a preliminary tally released Dec. 9, about 70 million adults had received the shots through pharmacies or doctors’ offices as of mid-November, compared with 58 million last year.

Although that appears to be a substantial increase, the C.D.C. does not know how many Americans who normally get their flu shots at work were unable to do so this year because of stay-at-home orders, said Dr. Ram Koppaka, the agency’s associate director for adult immunization. There was a big increase in flu shots delivered by pharmacies, and that may represent people who normally would have received the shots at work.

“The best we can say is that it appears that we are now about where we were last year,” Dr. Koppaka said.

Given that vaccines were available early, he added: “I’m disappointed that it’s not better than it is. We need to keep telling people that it’s not too late to get a flu shot.”

Normally, about 80 percent of all adults who get flu shots have had them by the end of November. But about nine million doses of vaccines that were meant for uninsured adults, and which the federal government purchased this year out of fear of a “twindemic,” are still being delivered, Dr. Koppaka said.

The finally tally of how many shots were taken will not be available until summer, after the flu season is over, he said.

Nonetheless, even the preliminary data showed disturbing trends in two important target groups: pregnant women and children. Only 54 percent of pregnant women have received flu vaccine this year, compared with 58 percent by this time last year. And, although about 48 percent of all children got flu shots both last year and this year, the percentage of Black children who got them dropped substantially this year, by 11 percentage points.

Dr. Koppaka said he could not yet account for those drops in coverage. Pregnant women might have been afraid to go to doctors or pharmacies for fear of getting Covid-19, and many Black children might have been missed because public schools that offer vaccines were closed — but that was just speculation, he emphasized.

Although Dr. Koppaka strongly encouraged unvaccinated Americans to get flu shots, the threat of a two-headed pandemic monster appears to be fading.

Because of the coronavirus pandemic, the C.D.C. is not currently posting forecasts on its FluSight page, where it predicts the future course of the flu season.

Kinsa Health, by contrast, is predicting that flu will stay at historic lows through February, when the season typically peaks. The company has a record of accurately predicting flu seasons several weeks ahead of the C.D.C.

C.D.C. surveillance data is based on weekly reports from doctors’ offices and hospitals noting the percentage of patient visits that are for flu symptoms. Because there are delays in reporting, sometimes for weeks, there is a lag between the time a flu arrives in a county and the agency’s confirmation that it is there.

Also, people who catch flu but never see a doctor are not captured in the C.D.C.’s surveillance net. People avoid doctors for many reasons, including a lack of insurance or because, this year, they are afraid of catching the coronavirus.

Kinsa receives about 100,000 readings each day from about two million thermometers connected to smartphones; the company claims it can detect local fever spikes down to the ZIP code level.

Both Covid-19 and flu can drive up the number of reported fevers, but flu outbreaks can be distinguished from Covid ones, Mr. Singh said.

The company has access to decades of historical flu data from 600 cities across the country, and there are patterns to how flu typically spreads in each city based on climate and population density, said Samuel D. Chamberlain, the company’s chief data scientist.

Also, because everyone is susceptible to the new coronavirus, Covid fevers surge and spread much faster across ZIP codes than do those caused by colds and flu, Mr. Singh said.

Moreover, users are asked to enter all their symptoms in the Kinsa app. Loss of smell and taste is a common Covid-19 symptom. Making things even simpler, the app asks users if they have had a positive coronavirus or flu test.

Currently, flu is at less than half its typical level for early December, Mr. Singh said. By February, when cases typically shoot to a sharp peak, its numbers should be down to about one-quarter of a typical seasonal apex, he predicted.

“In theory, the flu virus could be taking a year off,” said Dr. Arthur Reingold, head of epidemiology at the School of Public Health of the University of California, Berkeley.

He recently asked a friend who was treating Covid-19 cases at the University of California, San Francisco, hospital how many flu cases she had seen this year.

“The answer was zero,” he said. “That’s a relief, and certainly a relief to my friends who do clinical work.”

[Like the Science Times page on Facebook. | Sign up for the Science Times newsletter.]