Tagged your-feed-health

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 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.”

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.”

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.]

The Swiss Cheese Model of Pandemic Defense

The Swiss Cheese Model of Pandemic Defense

It’s not edible, but it can save lives. The virologist Ian Mackay explains how.

The multilayered “Swiss cheese” model was devised in the 1990s to improve industrial safety. Ian Mackay, a virologist at the University of Queensland, recently adapted it for the coronavirus pandemic. “It’s important to use more slices to prevent those volatile holes from aligning and letting virus through,” he said.
The multilayered “Swiss cheese” model was devised in the 1990s to improve industrial safety. Ian Mackay, a virologist at the University of Queensland, recently adapted it for the coronavirus pandemic. “It’s important to use more slices to prevent those volatile holes from aligning and letting virus through,” he said.Credit…Ian M. Mackay

By

  • Dec. 5, 2020, 5:00 a.m. ET

Lately, in the ongoing conversation about how to defeat the coronavirus, experts have made reference to the “Swiss cheese model” of pandemic defense.

The metaphor is easy enough to grasp: Multiple layers of protection, imagined as cheese slices, block the spread of the new coronavirus, SARS-CoV-2, the virus that causes Covid-19. No one layer is perfect; each has holes, and when the holes align, the risk of infection increases. But several layers combined — social distancing, plus masks, plus hand-washing, plus testing and tracing, plus ventilation, plus government messaging — significantly reduce the overall risk. Vaccination will add one more protective layer.

“Pretty soon you’ve created an impenetrable barrier, and you really can quench the transmission of the virus,” said Dr. Julie Gerberding, executive vice president and chief patient officer at Merck, who recently referenced the Swiss cheese model when speaking at a virtual gala fund-raiser for MoMath, the National Museum of Mathematics in Manhattan.

“But it requires all of those things, not just one of those things,” she added. “I think that’s what our population is having trouble getting their head around. We want to believe that there is going to come this magic day when suddenly 300 million doses of vaccine will be available and we can go back to work and things will return to normal. That is absolutely not going to happen fast.”

Rather, Dr. Gerberding said in a follow-up email, expect to see “a gradual improvement in protection, first among the highest need groups, and then more gradually among the rest of us.” Until vaccines are widely available and taken, she said, “we will need to continue masks and other common-sense measures to protect ourselves and others.”

In October, Bill Hanage, an epidemiologist at the Harvard T.H. Chan School of Public Health, retweeted an infographic rendering of the Swiss cheese model, noting that it included “things that are personal *and* collective responsibility — note the ‘misinformation mouse’ busy eating new holes for the virus to pass through.”

“One of the first principles of pandemic response is, or ought to be, clear and consistent messaging from trusted sources,” Dr. Hanage said in an email. “Unfortunately the independence of established authorities like the C.D.C. has been called into question, and trust needs to be rebuilt as a matter of urgency.” A catchy infographic is a powerful message, he said, but ultimately requires higher-level support.

The Swiss cheese concept originated with James T. Reason, a cognitive psychologist, now a professor emeritus at the University of Manchester, England, in his 1990 book, “Human Error.” A succession of disasters — including the Challenger shuttle explosion, Bhopal and Chernobyl — motivated the concept, and it became known as the “Swiss cheese model of accidents,” with the holes in the cheese slices representing errors that accumulate and lead to adverse events.

The model has been widely used by safety analysts in various industries, including medicine and aviation, for many years. (Dr. Reason did not devise the “Swiss cheese” label; that is attributed to Rob Lee, an Australian air-safety expert, in the 1990s.) The model became famous, but it was not accepted uncritically; Dr. Reason himself noted that it had limitations and was intended as a generic tool or guide. In 2004, at a workshop addressing an aviation accident two years earlier near Überlingen, Germany, he delivered a talk with the title, “Überlingen: Is Swiss cheese past its sell-by date?”

In 2006, a review of the model, published by the Eurocontrol Experimental Center, recounted that Dr. Reason, while writing the book chapter “Latent errors and system disasters,” in which an early version of the model appears, was guided by two notions: “the biological or medical metaphor of pathogens, and the central role played by defenses, barriers, controls and safeguards (analogous to the body’s autoimmune system).”

The cheese metaphor now pairs fairly well with the coronavirus pandemic. Ian M. Mackay, a virologist at the University of Queensland, in Brisbane, Australia, saw a smaller version on Twitter, but thought that it could do with more slices, more information. He created, with collaborators, the “Swiss Cheese Respiratory Pandemic Defense” and engaged his Twitter community, asking for feedback and putting the visualization through many iterations. “Community engagement is very high!” he said. Now circulating widely, the infographic has been translated into more than two dozen languages.

Dr. Mackay, a creator of the “Swiss Cheese Respiratory Pandemic Defense.”
Dr. Mackay, a creator of the “Swiss Cheese Respiratory Pandemic Defense.”Credit…Faye Sakura for The New York Times

“This multilayered approach to reducing risk is used in many industries, especially those where failure could be catastrophic,” Dr. Mackay said, via email. “Death is catastrophic to families, and for loved ones, so I thought Professor Reason’s approach fit in very well during the circulation of a brand-new, occasionally hidden, sometimes severe and occasionally deadly respiratory virus.”

The following is an edited version of a recent email conversation with Dr. Mackay.

Q. What does the Swiss cheese model show?

A. The real power of this infographic — and James Reason’s approach to account for human fallibility — is that it’s not really about any single layer of protection or the order of them, but about the additive success of using multiple layers, or cheese slices. Each slice has holes or failings, and those holes can change in number and size and location, depending on how we behave in response to each intervention.

Take masks as one example of a layer. Any mask will reduce the risk that you will unknowingly infect those around you, or that you will inhale enough virus to become infected. But it will be less effective at protecting you and others if it doesn’t fit well, if you wear it below your nose, if it’s only a single piece of cloth, if the cloth is a loose weave, if it has an unfiltered valve, if you don’t dispose of it properly, if you don’t wash it, or if you don’t sanitize your hands after you touch it. Each of these are examples of a hole. And that’s in just one layer.

To be as safe as possible, and to keep those around you safe, it’s important to use more slices to prevent those volatile holes from aligning and letting virus through.

Q. What have we learned since March?

A. Distance is the most effective intervention; the virus doesn’t have legs, so if you are physically distant from people, you avoid direct contact and droplets. Then you have to consider inside spaces, which are especially in play during winter or in hotter countries during summer: the bus, the gym, the office, the bar or the restaurant. That’s because we know SARS-CoV-2 can remain infectious in aerosols (small floaty droplets) and we know that aerosol spread explains Covid-19 superspreading events. Try not to be in those spaces with others, but if you have to be, minimize your time there (work from home if you can) and wear a mask. Don’t go grocery shopping as often. Hold off on going out, parties, gatherings. You can do these things later.

We don’t talk about eye coverings much, but we should, because we don’t know enough about the role of eyes in transmission. We do know that eyes are a window to the upper respiratory tract.

Q. Where does the “misinformation mouse” fit in?

A. The misinformation mouse can erode any of those layers. People who are uncertain about an intervention may be swayed by a loud and confident-sounding voice proclaiming that a particular layer is ineffective. Usually, that voice is not an expert on the subject at all. When you look to the experts — usually to your local public health authorities or the World Health Organization — you’ll find reliable information.

An effect doesn’t have to be perfect to reduce your risk and the risk to those around you. We need to remember that we’re all part of a society, and if we each do our part, we can keep each other safer, which pays off for us as well.

Another example: We look both ways for oncoming traffic before crossing a road. This reduces our risk of being hit by a car but doesn’t reduce it to zero. A speeding car could still come out of nowhere. But if we also cross with the lights, and keep looking as we walk, and don’t stare at our phone, we drastically reduce our risk of being hit.

We’re already used to doing that. When we listen to the loud nonexperts who have no experience in protecting our health and safety, we are inviting them to have an impact in our lives. That’s not a risk we should take. We just need to get used to these new risk-reduction steps for today’s new risk — a respiratory virus pandemic, instead of a car.

Q. What is our individual responsibility?

A. We each need to do our part: stay apart from others, wear a mask when we can’t, think about our surroundings, for example. But we can also expect our leadership to be working to create the circumstances for us to be safe — like regulations about the air exchange inside public spaces, creating quarantine and isolation premises, communicating specifically with us (not just at us), limiting border travel, pushing us to keep getting our health checks, and providing mental health or financial support for those who suffer or can’t get paid while in a lockdown.

Q. How can we make the model stick?

A. We each use these approaches in everyday life. But for the pandemic, this all feels new and like a lot of extra work. Because everything is new. In the end, though, we’re just forming new habits. Like navigating our latest phone’s operating system or learning how to play that new console game I got for my birthday. It might take some time to get across it all, but it’s worthwhile. In working together to reduce the risk of infection, we can save lives and improve health.

And as a bonus, the multilayered risk reduction approach can even decrease the number of times we get the flu or a bad chest cold. Also, sometimes slices sit under a mandate — it’s important we also abide by those rules and do what the experts think we should. They’re looking out for our health.

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

‘Nobody Sees Us’: Testing-Lab Workers Strain Under Demand

April Abbott, director of microbiology at Deaconess Hospital in Evansville, Ind., a mother of three who keeps a bed in her office for when her duties keep her overnight. “There is always more work to be done than the hours to do it in,” she said.
April Abbott, director of microbiology at Deaconess Hospital in Evansville, Ind., a mother of three who keeps a bed in her office for when her duties keep her overnight. “There is always more work to be done than the hours to do it in,” she said.Credit…Kaiti Sullivan for The New York Times

‘Nobody Sees Us’: Testing-Lab Workers Strain Under Demand

Laboratory technologists have been working nonstop to help the nation diagnose an ever-growing number of coronavirus cases.

April Abbott, director of microbiology at Deaconess Hospital in Evansville, Ind., a mother of three who keeps a bed in her office for when her duties keep her overnight. “There is always more work to be done than the hours to do it in,” she said.Credit…Kaiti Sullivan for The New York Times

Katherine J. Wu

By

  • Dec. 3, 2020, 5:00 a.m. ET

In March, April Abbott dragged a hospital bed into her office at Deaconess Hospital in Evansville, Ind. In the nine months since, she has slept in it a half-dozen times while working overnight in her clinical microbiology laboratory, where a team of some 40 scientists toils around the clock running coronavirus tests.

These all-night stints in the lab pull Dr. Abbott, the director of microbiology at Deaconess, away from her husband and three children, the oldest of whom is 8. A couple of times a week, she heads home for dinner, then drives back to work after the kids have gone to bed. She is at the lab when machines break. She is there to vet testing protocols for the lab. She is there when new testing sites open, flooding the lab with more samples to process.

“I do it because there is always more work to be done than the hours to do it in,” she said.

Nearly a year into a pandemic that has claimed more than 272,000 American lives, some 192 million tests for the coronavirus have been processed nationwide. Millions more will be needed to detect and contain the virus in the months ahead. Behind these staggering figures are thousands of scientists who have been working nonstop to identify the coronavirus in the people it infects.

Across the nation, testing teams are grappling with burnout, repetitive-stress injuries and an overwhelming sense of doom. As supply chains sputter and laboratories rush to keep pace with diagnostic demand, experts warn that the most severe shortage stymieing America’s capacity to test is not one that can be solved by a wider production line or a more efficient machine. It is a dearth of human power: the dwindling ranks in a field that much of the public does not know even exists.

When shortages arise, “there’s workarounds for almost everything else,” said Karissa Culbreath, the medical director and infectious disease division chief at TriCore Reference Laboratories in New Mexico. “But people are irreplaceable.”

In the absence of trained workers to process and analyze the nation’s tests, America’s diagnostic infrastructure will not merely wrinkle and slow, experts said. It will collapse.

“Doctors and nurses are very visible, but we work behind the scenes,” said Marissa Larson, a medical laboratory scientist supervisor at the University of Kansas Health System. “And we are underwater.”

‘I don’t even know where to start’

Darcy Velasquez, a medical technologist at Children’s Hospital Colorado in Aurora, begins her shifts at 5:30 a.m. with a refrigerator of up to 500 tubes, trying to clear a backlog before another shipment arrives at 8 a.m.
Darcy Velasquez, a medical technologist at Children’s Hospital Colorado in Aurora, begins her shifts at 5:30 a.m. with a refrigerator of up to 500 tubes, trying to clear a backlog before another shipment arrives at 8 a.m.Credit…Matthew Staver for The New York Times

The gold standard in coronavirus diagnostics hinges on a decades-old laboratory method called polymerase chain reaction, or P.C.R. The method is a signal amplifier: It can copy genetic material, including fragments of the genome of the coronavirus, over and over until it reaches detectable levels, making the virus discoverable even when it is extremely scarce in the body. P.C.R. is the metric against which all new testing techniques are compared; in the diagnostic landscape, few can match its ability to root out infection.

But such accuracy comes at a cost. Even highly automated forms of P.C.R. require people to handle tubes, babysit machines and scrutinize ambiguous results.

P.C.R.-based coronavirus tests also deal in DNA, the molecular language in which the human genome is written. The coronavirus, however, stores its genetic information in a close cousin called RNA, which must first be carefully extracted from virus particles, then converted to its more testable counterpart before diagnostics can proceed.

When laboratories are well stocked, P.C.R. diagnostics can run from start to finish in just a few hours. But since the spring, laboratories around the country have been hamstrung by severe, often unpredictable shortages of chemicals and plasticware needed for these protocols.

And caseloads have skyrocketed; America’s testing capacity has increased since March, but it has been vastly overtaken by the demand for tests.

“The spring pales in comparison to what we are experiencing now,” said Dr. Culbreath, of TriCore, which has run more than 600,000 coronavirus tests.

Amid the pandemonium, labs must still work through their queues for other infectious disease tests, including for sexually transmitted infections. “Labs are trying to maintain our standard of operation with everything else, with a pandemic on top of it,” Dr. Culbreath said.

Darcy Velasquez, a medical technologist at Children’s Hospital Colorado in Aurora, where cases continue to surge, is fighting to keep pace with some of her institution’s highest sample volumes yet. Her shifts in the lab begin at 5:30 a.m., sometimes to a double-door refrigerator already brimming with 500 tubes, each containing a fresh patient swab and a small volume of liquid — more than a full day’s work for one person.

Ms. Velasquez typically spends the first couple hours of her day frantically trying to clear as much of the backlog as she can before another batch arrives around 8 a.m., when the local clinic opens.

As much as an hour of that time might be spent simply de-swabbing samples: manually unscrewing and rescrewing caps and plucking out swabs, all without contaminating one sample with the contents of another.

“Sometimes you walk into these refrigerators full of specimens and you think, ‘I don’t even know where to start,’” Ms. Velasquez said.

Taylor Smith, a virologist and technologist for the Georgia Department of Public Health, with her dog, Spunk.Credit…Johnathon Kelso for The New York Times

At Georgia’s state public health laboratory, direct handling of patient samples must be done with extra safeguards to minimize the chances of exposing personnel to infectious virus. Taylor Smith, a virologist and technologist at the lab, spends a large fraction of her workday in a full-body gown, sleeve covers, two pairs of gloves, an N95 respirator and goggles.

Simply donning it all is exhausting. And although Ms. Smith has long been deft with lab instruments, the work always feels high-stakes, she said: “You’re constantly thinking about how to not contaminate yourself.”

To keep their experiments running, lab workers must be proficient mechanics. The instruments needed for diagnostic tests were not built to run continuously for months on end. But as more facilities transition to 24/7 testing, malfunctions and breakdowns have become more common, requiring people to fix them.

Tyler Murray, a clinical laboratory scientist at the University of Texas Medical Branch in Galveston, spends his days listening for telltale alarms — a sign that one of his instruments has failed or is low on chemical ingredients.

“I make sure I talk nicely to them,” Mr. Murray said of the lab’s machines, which he decorates with gleaming gold stars when they perform at their best. “I say, ‘Hey bud, you worked hard this week, I’m proud of you.’”

But morale is low among the humans. After 10-hour shifts at U.T.M.B., Mr. Murray heads home and lies on the floor beside his two cats, Arya and Cleo. “The fatigue builds,” he said. “You can’t help but feel it.”

Tyler Murray, a clinical laboratory scientist at the University of Texas Medical Branch in Galveston, with Cleo, one of his two cats.Credit…Go Nakamura for The New York Times

The invisible work force

The monotonous motions that lab workers engage in daily take a physical and mental toll. Technologists are nursing repetitive-use injuries, a result of hours of maneuvering tubes and pipettes, which take up and dispense liquids with the press of a plunger. Workers must also be vigilant sanitizers, pausing regularly to swap out soiled gloves, clear their workspaces of plastic debris and scour surfaces with harsh chemicals that leave their clothes freckled with stains.

“We’re accustomed to holding things up in the background,” said Natalie Williams-Bouyer, the director of the division of clinical microbiology at the University of Texas Medical Branch in Galveston. “We enjoy doing it because we know we’re helping people.”

But the enduring anonymity of testing labs has begun to splinter some spirits. Elizabeth Stoeppler, a senior medical technologist in the molecular microbiology lab at the University of North Carolina’s School of Medicine, said that an old volleyball injury, which inflamed a tendon in her elbow years ago, had flared up after months of long stints in the lab. A few of her co-workers are wrestling with carpal tunnel syndrome.

The strain has begun to affect Ms. Stoeppler outside of the lab. She bolts awake at 3 a.m., panicked about the previous day’s work. She recently started a prescription medication to improve her chances of getting a full night’s sleep.

“There’s signs everywhere that say, ‘Heroes work here,’” she said of her hospital. She loves her job, she added. “But nobody sees us. We’re just in the basement, or in the back.”

On a good day in a diagnostics lab, the phone might ring only a few times, with messages from clinicians inquiring about samples. But when “things are going poorly, it just rings off the hook,” said Rachael Liesman, the director of clinical microbiology at the University of Kansas Health System, where she frequently clocks 15-hour shifts.

To keep the lab on track, Dr. Liesman has put in some hours running tests herself — a task that is not a part of her normal job description. “It’s very strange to have your director on the bench,” said Ms. Larson, a supervisor in the lab. “When you see that, some flare guns should be going up.”

Marissa Larson, left, a medical laboratory scientist supervisor at the University of Kansas Health System, and Rachael Liesman, its director of clinical microbiology.Credit…Barrett Emke for The New York Times

In mid-November, Dr. Liesman’s lab suffered a three-day stretch during which a supply of chemicals nearly ran dry on a Friday, then a pair of machines failed on Saturday and Sunday.

“We were basically drowning in specimens” by Monday, she said. “I was paged by three different providers while brushing my teeth.”

Morale in the labs has flagged as the country continues to shatter records for caseloads, hospitalizations and deaths. The nation’s testing experts know these statistics better than anyone: They count the numbers themselves, sample by sample. But they are also easy targets of criticism and complaint.

“There is always this undercurrent of, it’s never good enough,” said Dr. Abbott, of Deaconess Hospital in Indiana. “It’s devastating. We’re working as hard as we can.”

Chelsa Ashley, a medical laboratory scientist at Deaconess, aches to be home with her three children, to whom she is a single mother, after 13-hour shifts in the lab. Once there, she struggles to leave her work behind.

“There’s that panicked feeling that I should have stayed to take care of our community samples,” she said. “There’s guilt, when you walk away.”

In the past few months, Ms. Ashley’s children, who are 18, 13 and 10, have had to become substantially more self-sufficient. Shaylan, her youngest, rouses herself from bed at 5:50 a.m. every day to spend a few moments with her mother before she heads off to work.

“Even if it’s only 10 minutes, it’s 10 minutes that we talk,” Ms. Ashley said. “That is one thing that has not changed.”

‘A dying breed’

For some, the tidal wave of stress brought on by the pandemic has proved untenable. Since March, scientists have trickled out of laboratories, leaving chasms of expertise in a field that for years has struggled to recruit fresh talent.

Joanne Bartkus, the former director of the Minnesota Department of Public Health Laboratory, retired from her position in May after a dozen years on the job. She pinned one of the pandemic’s crucial inflection points to March 6, the day President Trump publicly remarked that “anybody that wants a test can get a test.”

“That was when the poop hit the fan,” Dr. Bartkus said. Within about a week, her team went from receiving fewer than a dozen coronavirus testing samples each day to being inundated with roughly 1,000 daily specimens.

It was unlike anything Dr. Bartkus had seen in her years at the institution. In 2009, the year of the H1N1 flu pandemic, Minnesota’s public health laboratory tested about 6,000 patient samples. This spring, it broke that record in a couple of weeks.

Dr. Bartkus, who is 65, had already planned to retire before the year was up. By the time April came, she had hastened her timeline to May: “It didn’t take me long before I said, ‘OK, I’m done with this.’”

In interviews, several scientists noted that they were struggling to fill vacancies in their labs, some that were left open by overwhelmed technologists who had recently quit their jobs. While the need for such workers has grown in recent years, the number of training programs that build these skill sets has dropped.

“Medical technologists are a dying breed,” Ms. Stoeppler, of the University of North Carolina, said.

Natalie Williams-Bouyer, the director of the division of clinical microbiology at the University of Texas Medical Branch in Galveston. “I hope people can see us now,” she said.Credit…Go Nakamura for The New York Times

In Indiana, Dr. Abbott, of Deaconess Hospital, said her team had already performed more than 100,000 tests for the coronavirus. But the most chaotic months are most likely still ahead.

For the first time in nine years, Dr. Abbott is doing hands-on work in the lab to help her staff cope with rising demand. She has yet to take more than a day off at a time since the pandemic’s start, but insists that she can soldier on: “This is out of the sheer will of not wanting to be beaten by this pandemic.”

In the mini-refrigerator in her office, next to rotating bags of salad greens and a small cavalry of Diet Cokes, sits an unopened bottle of champagne that she purchased in March, intending to uncork it upon reaching a worthy testing milestone. Nothing has yet felt like enough.

“I can’t tell you what will feel like a reason to celebrate at this point,” Dr. Abbott said. “Ask me after the next 100,000 tests.”

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

Their Teeth Fell Out. Was It Another Covid-19 Consequence?

Earlier this month, Farah Khemili popped a wintergreen breath mint in her mouth and noticed a strange sensation: a bottom tooth wiggling against her tongue.

Ms. Khemili, 43, of Voorheesville, N.Y., had never lost an adult tooth. She touched the tooth to confirm it was loose, initially thinking the problem might be the mint. The next day, the tooth flew out of her mouth and into her hand. There was neither blood nor pain.

Ms. Khemili survived a bout with Covid-19 this spring, and has joined an online support group as she has endured a slew of symptoms experienced by many other “long haulers”: brain fog, muscle aches and nerve pain.

There’s no rigorous evidence yet that the infection can lead to tooth loss or related problems. But among members of her support group, she found others who also described teeth falling out, as well as sensitive gums and teeth turning gray or chipping.

She and other survivors unnerved by Covid’s well-documented effects on the circulatory system, as well as symptoms such as swollen toes and hair loss, suspect a connection to tooth loss as well. But some dentists, citing a lack of data, are skeptical that Covid-19 alone could cause dental symptoms.

“It’s extremely rare that teeth will literally fall out of their sockets,” said Dr. David Okano, a periodontist at the University of Utah in Salt Lake City.

But existing dental problems may worsen as a result of Covid-19, he added, especially as patients recover from the acute infections and contend with its long-term effects.

And some experts say that doctors and dentists need to be open to such possibilities, especially because more than 47 percent of adults 30 years or older have some form of periodontal disease, including infections and inflammation of the gums and bone that surround teeth, according to a 2012 report from the Centers for Disease Control and Prevention.

“We are now beginning to examine some of the bewildering and sometimes disabling symptoms that patients are suffering months after they’ve recovered from Covid,” including these accounts of dental issues and teeth loss, said Dr. William W. Li, president and medical director of the Angiogenesis Foundation, a nonprofit that studies the health and disease of blood vessels.

While Ms. Khemili had become more diligent about her dental care, she had a history of dental issues before contracting the coronavirus. When she went to the dentist the day after her tooth came out, he found that her gums were not infected but she had significant bone loss from smoking. He referred Ms. Khemili to a specialist to handle a reconstruction. The dental procedure is likely to cost her just shy of $50,000.

The same day Ms. Khemili’s tooth fell out, her partner went on Survivor Corp, a Facebook page for people who have lived through Covid-19. There, he found that Diana Berrent, the page’s founder, was reporting that her 12-year-old son had lost one of his adult teeth, months after he had a mild case of Covid-19. (Unlike Ms. Khemili, Ms. Berrent’s son had normal and healthy teeth with no underlying disease, according to his orthodontist.)

Others in the Facebook group have posted about teeth falling out without bleeding. One woman lost a tooth while eating ice cream. Eileen Luciano of Edison, N.J., had a top molar pop out in early November when she was flossing.

“That was the last thing that I thought would happen, that my teeth would fall out,” Ms. Luciano said.

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

Teeth falling out without any blood is unusual, Dr. Li said, and provides a clue that there might be something going on with the blood vessels in the gums.

The new coronavirus wreaks havoc by binding to the ACE2 protein, which is ubiquitous in the human body. Not only is it found in the lungs, but also on nerve and endothelial cells. Therefore, Dr. Li says, it’s possible that the virus has damaged the blood vessels that keep the teeth alive in Covid-19 survivors; that also may explain why those who have lost their teeth feel no pain.

It’s also possible that the widespread immune response, known as a cytokine storm, may be manifesting in the mouth.

“If a Covid long hauler’s reaction is in the mouth, it’s a defense mechanism against the virus,” said Dr. Michael Scherer, a prosthodontist in Sonora, Calif. Other inflammatory health conditions, such as cardiovascular disease and diabetes, he said, also correlate with gum disease in the same patients.

“Gum disease is very sensitive to hyper-inflammatory reactions, and Covid long haulers certainly fall into that category,” Dr. Scherer said.

Dentists haven’t seen many of these cases, and some dismiss these individual claims. But physicians like Dr. Li say Covid-19’s surprises require that the profession be on the lookout for unexpected consequences of the disease.

“Patients may be bringing in new findings,” he said, and physicians and dentists need to cooperate on understanding the effects of long-term Covid-19 on teeth.

For now, Ms. Khemili hopes her story may serve as a cautionary tale. If people aren’t taking the proper precautions to protect themselves from the coronavirus, “they could be looking at something like this.”