Tagged Centers for Disease Control and Prevention

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.”

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Pressure Grows for States to Open Vaccines to More Groups of People

Pressure Grows for States to Open Vaccines to More Groups of People

Some states are already expanding eligibility to people 65 and over, even though millions of people the C.D.C. recommends go first — health care workers and nursing home residents — have yet to get shots.

Gov. Ron DeSantis of Florida, right, during vaccinations at the John Knox Village nursing home in Pompano Beach, Fla., last month.
Gov. Ron DeSantis of Florida, right, during vaccinations at the John Knox Village nursing home in Pompano Beach, Fla., last month.Credit…Marta Lavandier/Associated Press
Abby Goodnough

  • Jan. 9, 2021, 12:00 p.m. ET

Just weeks into the country’s coronavirus vaccination effort, states have begun broadening access to the shots faster than planned, amid tremendous public demand and intense criticism about the pace of the rollout.

Some public health officials worry that doing so could bring even more chaos to the complex operation and increase the likelihood that some of the highest-risk Americans will be skipped over. But the debate over how soon to expand eligibility is intensifying as deaths from the virus continue to surge, hospitals are overwhelmed with critically ill patients and millions of vaccine doses delivered last month remain in freezers.

Governors are under enormous pressure from their constituents — especially older people, who vote in great numbers and face the highest risk of dying from the virus — to get the doses they receive into arms swiftly. President-elect Joseph R. Biden Jr.’s decision, announced Friday, to release nearly all available doses to the states when he takes office on Jan. 20, rather than holding half to guarantee each recipient gets a booster shot a few weeks after the first, is likely to add to that pressure.

Some states, including Florida, Louisiana and Texas, have already expanded who is eligible to get a vaccine now, even though many people in the first priority group recommended by the Centers for Disease Control and Prevention — the nation’s 21 million health care workers and three million residents of nursing homes and other long-term care facilities — have not yet received a shot.

On Friday afternoon, New York became the latest state to do so, announcing that it would allow people 75 and over and certain essential workers to start receiving a vaccine on Monday.

But reaching a wider swath of the population requires much more money than states have received for the task, many health officials say, and more time to fine-tune systems for moving surplus vaccine around quickly, to increase the number of vaccination sites and people who give the shots, and to establish reliable appointment systems to prevent endless lines and waits.

Some states’ expansions have led to frantic and often futile efforts by older people to get vaccinated. After Florida opened up vaccinations to anyone 65 and older late last month, the demand was so great that new online registration portals quickly overloaded and crashed, people spent hours on the phone trying to secure appointments and others waited overnight at scattered pop-up sites offering shots on a first-come first-served basis.

Similar scenes have played out in parts of Texas, Tennessee and a handful of other states.

Still, with C.D.C. data suggesting that only about a third of the doses distributed so far have been used, Alex M. Azar II, the health and human services secretary, told reporters this past week: “It would be much better to move quickly and end up vaccinating some lower-priority people than to let vaccines sit around while states try to micromanage this process. Faster administration would save lives right now, which means we cannot let the perfect be the enemy of the good.”

Boxes of Moderna’s vaccine were prepared for shipment at a distribution center in Olive Branch, Miss., last month.
Boxes of Moderna’s vaccine were prepared for shipment at a distribution center in Olive Branch, Miss., last month.Credit…Pool photo by Paul Sancya

The C.D.C. guidelines were drawn up by an independent committee of medical and public health experts that advises the agency on immunization practices; it deliberated for months about who should get vaccinated initially, while supplies were still very limited. The committee weighed scientific evidence about who is most at risk of getting very sick or dying from Covid-19, as well as ethical questions, such as how best to ensure equal access among different races and socioeconomic groups.

Although the committee’s recommendations are nonbinding, states usually follow them; in this case, the committee suggests that states might consider expanding to additional priority groups “when demand in the current phase appears to have been met,” “when supply of authorized vaccine increases substantially” or “when vaccine supply within a certain location is in danger of going unused.”

Dr. Kevin Ault, an obstetrician at the University of Kansas Medical Center who serves on the advisory committee that came up with the C.D.C. guidelines, said that it was reasonable for states to start vaccinating new groups before finishing others, but that they should be careful about exacerbating inequities and biting off more than they can chew.

“Obviously if you’re going to vaccinate that group you need to have a well-thought-out plan in hand,” he said, referring to the over-65 population. “Having people camping out for vaccine is less than ideal, I would say.”

He added, “We put a lot of thought and effort into our guidelines, and I think they are good.”

After the first vaccines were given in mid-December, a dichotomy emerged between governors who were adhering precisely to the guidelines and others who moved quickly to populations beyond health care workers and nursing home residents.

Until Friday, Gov. Andrew M. Cuomo of New York, a Democrat, had threatened to penalize hospitals that provided shots to people who are not health care workers. By contrast, Gov. Ron DeSantis of Florida, a Republican, traveled to retirement communities around his state to emphasize the importance of getting people 65 and older, who number more than five million there, immunized fast.

“In Florida we’ve got to put our parents and grandparents first,” Mr. DeSantis said at The Villages, the nation’s largest retirement community, just before Christmas.

Gov. Andrew Cuomo of New YorkCredit…Andrew Kelly/Reuters
Gov. Mike DeWine of OhioCredit…Tony Dejak/Associated Press
Gov. Greg Abbott of TexasCredit…Eric Gay/Associated Press
Gov. Larry Hogan of MarylandCredit…Jonathan Ernst/Reuters

Decisions on how soon to expand eligibility for the shots have not fallen neatly along partisan lines.


Covid-19 Vaccines ›


Answers to Your Vaccine Questions

While the exact order of vaccine recipients may vary by state, most will likely put medical workers and residents of long-term care facilities first. If you want to understand how this decision is getting made, this article will help.

Life will return to normal only when society as a whole gains enough protection against the coronavirus. Once countries authorize a vaccine, they’ll only be able to vaccinate a few percent of their citizens at most in the first couple months. The unvaccinated majority will still remain vulnerable to getting infected. A growing number of coronavirus vaccines are showing robust protection against becoming sick. But it’s also possible for people to spread the virus without even knowing they’re infected because they experience only mild symptoms or none at all. Scientists don’t yet know if the vaccines also block the transmission of the coronavirus. So for the time being, even vaccinated people will need to wear masks, avoid indoor crowds, and so on. Once enough people get vaccinated, it will become very difficult for the coronavirus to find vulnerable people to infect. Depending on how quickly we as a society achieve that goal, life might start approaching something like normal by the fall 2021.

Yes, but not forever. The two vaccines that will potentially get authorized this month clearly protect people from getting sick with Covid-19. But the clinical trials that delivered these results were not designed to determine whether vaccinated people could still spread the coronavirus without developing symptoms. That remains a possibility. We know that people who are naturally infected by the coronavirus can spread it while they’re not experiencing any cough or other symptoms. Researchers will be intensely studying this question as the vaccines roll out. In the meantime, even vaccinated people will need to think of themselves as possible spreaders.

The Pfizer and BioNTech vaccine is delivered as a shot in the arm, like other typical vaccines. The injection won’t be any different from ones you’ve gotten before. Tens of thousands of people have already received the vaccines, and none of them have reported any serious health problems. But some of them have felt short-lived discomfort, including aches and flu-like symptoms that typically last a day. It’s possible that people may need to plan to take a day off work or school after the second shot. While these experiences aren’t pleasant, they are a good sign: they are the result of your own immune system encountering the vaccine and mounting a potent response that will provide long-lasting immunity.

No. The vaccines from Moderna and Pfizer use a genetic molecule to prime the immune system. That molecule, known as mRNA, is eventually destroyed by the body. The mRNA is packaged in an oily bubble that can fuse to a cell, allowing the molecule to slip in. The cell uses the mRNA to make proteins from the coronavirus, which can stimulate the immune system. At any moment, each of our cells may contain hundreds of thousands of mRNA molecules, which they produce in order to make proteins of their own. Once those proteins are made, our cells then shred the mRNA with special enzymes. The mRNA molecules our cells make can only survive a matter of minutes. The mRNA in vaccines is engineered to withstand the cell’s enzymes a bit longer, so that the cells can make extra virus proteins and prompt a stronger immune response. But the mRNA can only last for a few days at most before they are destroyed.

Gov. Larry Hogan of Maryland, a Republican, announced Tuesday that he would immediately switch to what he called the “Southwest Airlines model” for vaccine allocation, referring to the airline’s open seating policy. “We’re no longer going to be waiting for all the members of a particular priority group to be completed,” he said, “before we move on to begin the next group in line.”

Gov. Mike DeWine of Ohio, a Republican, urged patience in a news briefing Tuesday as he declined to estimate when the state would start vaccinating people beyond the first priority group, known as “1a.”

“We’re asking every health department, ‘Don’t go outside 1a, stay within your lane,’” he said, adding about the vaccines, “This is a scarce commodity.”

By Thursday Mr. DeWine had set a date for people 80 and older to start getting the vaccine — Jan. 19 — and said he would phase in everyone 65 and older, as well as teachers, by Feb. 8.

The reasons so many doses received by states have not yet been administered to the first priority group are manifold. The fact that vaccination began around Christmas, when many hospital employees were taking vacation, slowed things. More health care workers are refusing to get the vaccine than many of their employers expected, and some hospitals and clinics received more doses than they needed but felt constrained by state rules from giving them to people outside the first priority groups. Some initially worried they could not even offer leftover doses in open vials to people in lower priority groups and let them go to waste.

Frontline health care workers and people age 65 and older waited to be vaccinated at a sports complex in Fort Myers, Fla., last month.Credit…Octavio Jones for The New York Times

And federal funding for vaccination efforts has been slow to reach states and localities: They got only $350 million through the end of last year, a little more than $1 per resident of the country. The economic rescue package that Congress passed in December included $8 billion for vaccine distribution that state health officials had long sought, but the first tranche of it, about $3 billion, is only now starting to be sent out.

“There was great funding in the development of these products, great funding in the infrastructure to ship them and get them out,” said Dr. Steven Stack, commissioner of the Kentucky Department for Public Health. “But then there was no funding provided of meaning for administering the vaccine, which is the last mile of this journey.”

The C.D.C. has recommended that a “1b” group consisting of people 75 and older and certain essential workers, including teachers, corrections officers and grocery store employees, be vaccinated next. The second group is much larger, about 50 million people. And the third recommended priority group — people 65 to 74, anyone 16 and older with high-risk medical conditions, and essential workers not already reached — numbers almost 130 million.

Pfizer and Moderna have pledged to deliver enough vaccine doses for 100 million people to each get the two necessary shots by the end of March, and many more in the second quarter. Several other vaccine candidates are far along in the pipeline, and if approved for emergency use here could help ramp up distribution more quickly.

The C.D.C. committee initially considered recommending that a wide range of essential workers get vaccinated before older Americans. Its rationale was that many essential workers are low-wage people of color, who have been hit disproportionately hard by the virus and had limited access to good health care. That sparked a backlash, and several governors, including Mr. DeSantis, quickly made clear they would cater to older people first.

Alex M. Azar, the health and human services secretary, left, and Surgeon General Jerome Adams, right, during a vaccination at George Washington University Hospital on Dec. 14.Credit…Pool photo by Jacquelyn Martin-Pool

Dr. Mark McClellan, who formerly headed the F.D.A. and now runs Duke University’s health policy center, said that while pushing ahead to vaccinate older people and other particularly vulnerable groups would accelerate the overall effort, “we’re going to be missing a lot of higher-risk individuals along the way.”

“I do worry about that becoming uneven in terms of access,” he said during a press briefing, “with lower-income groups, minority groups maybe in a tougher position if we don’t make it very easy for people in these high-risk groups to get vaccinated.”

Dr. Marcus Plescia, the chief medical officer for the Association of State and Territorial Health Officials, said he was surprised to hear federal officials like Mr. Azar and Dr. Jerome Adams, the surgeon general, advocate expanding vaccine access so broadly so soon.

“We didn’t come up with priority populations to slow things down, but because we knew there would be limited numbers of doses,” Dr. Plescia said. “If we try to do this in an equitable, fair way, it’s not going to be as fast as if our only goal is to get vaccine into as many arms as possible.”

Whether or not they are widening access now, governors are ramping up pressure on hospitals to use their allocated doses more quickly. Mr. Cuomo threatened to fine those that did not use their initial allocations by the end of this past week and not send them any more.

Mr. Hogan warned hospitals this past week, “Either use the doses that have been allocated to you or they will be directed to another facility or provider.”

He Was Hospitalized for Covid-19. Then Hospitalized Again. And Again.

Credit…Emily Rose Bennett for The New York Times

He Was Hospitalized for Covid-19. Then Hospitalized Again. And Again.

Significant numbers of coronavirus patients experience long-term symptoms that send them back to the hospital, taxing an already overburdened health system.

Credit…Emily Rose Bennett for The New York Times

Pam Belluck

  • Dec. 30, 2020, 3:00 a.m. ET

The routine things in Chris Long’s life used to include biking 30 miles three times a week and taking courses toward a Ph.D. in eight-week sessions.

But since getting sick with the coronavirus in March, Mr. Long, 54, has fallen into a distressing new cycle — one that so far has landed him in the hospital seven times.

Periodically since his initial five-day hospitalization, his lungs begin filling again; he starts coughing uncontrollably and runs a low fever. Roughly 18 days later, he spews up greenish-yellow fluid, signaling yet another bout of pneumonia.

Soon, his oxygen levels drop and his heart rate accelerates to compensate, sending him to a hospital near his home in Clarkston, Mich., for several days, sometimes in intensive care.

“This will never go away,” he said, describing his worst fear. “This will be my going-forward for the foreseeable future.”

Nearly a year into the pandemic, it’s clear that recovering from Covid-19’s initial onslaught can be an arduous, uneven journey. Now, studies reveal that a significant subset of patients are having to return to hospitals, sometimes repeatedly, with complications triggered by the disease or by the body’s efforts to defeat the virus.

Even as vaccines give hope for stopping the spread of the virus, the surge of new cases portends repeated hospitalizations for more patients, taxing medical resources and turning some people’s path to recovery into a Sisyphean odyssey that upends their lives.

“It’s an urgent medical and public health question,” said Dr. Girish Nadkarni, an assistant professor of medicine at Mount Sinai Hospital in New York, who, with another assistant professor, Dr. Anuradha Lala, is studying readmissions of Covid-19 patients.

Data on rehospitalizations of coronavirus patients are incomplete, but early studies suggest that in the United States alone, tens of thousands or even hundreds of thousands could ultimately return to the hospital.

A study by the Centers for Disease Control and Prevention of 106,543 coronavirus patients initially hospitalized between March and July found that one in 11 was readmitted within two months of being discharged, with 1.6 percent of patients readmitted more than once.

In another study of 1,775 coronavirus patients discharged from 132 V.A. hospitals in the pandemic’s early months, nearly a fifth were rehospitalized within 60 days. More than 22 percent of them needed intensive care, and 7 percent required ventilators.

And in a report on 1,250 patients discharged from 38 Michigan hospitals from mid-March to July, 15 percent were rehospitalized within 60 days.

Recurring admissions don’t just involve patients who were severely ill the first time around.

“Even if they had a very mild course, at least one-third have significant symptomology two to three months out,” said Dr. Eleftherios Mylonakis, chief of infectious diseases at Brown University’s Warren Alpert Medical School and Lifespan hospitals, who co-wrote another report. “There is a wave of readmissions that is building, because at some point these people will say ‘I’m not well.’”

Many who are rehospitalized were vulnerable to serious symptoms because they were over 65 or had chronic conditions. But some younger and previously healthy people have returned to hospitals, too.

When Becca Meyer, 31, of Paw Paw, Mich., contracted the coronavirus in early March, she initially stayed home, nursing symptoms such as difficulty breathing, chest pain, fever, extreme fatigue and hallucinations that included visions of being attacked by a sponge in the shower.

Ms. Meyer, a mother of four, eventually was hospitalized for a week in March and again in April. She was readmitted for an infection in August and for severe nausea in September, according to medical records, which labeled her condition “long haul Covid-19.”

Because she couldn’t hold down food, doctors discharged her with a nasal feeding tube connected to protein-and-electrolyte formula on a pole, which, she said, “I’m supposed to be attached to 20 hours a day.”

Feeding tube issues required hospitalization for nearly three weeks in October and a week in December. She has been unable to resume her job in customer service, spent the summer using a walker, and has had a home health nurse for weeks.

“It’s been a roller coaster since March and I’m now in the downswing of it, where I’m back to being in bed all the time and not being able to eat much, coughing a lot more, having more chest pain,” she said.

Readmissions strain hospital resources, and returning patients may be exposed to new infections or develop muscle atrophy from being bedridden. Mr. Long and Ms. Meyer said they contracted the bacterial infection C. difficile during rehospitalizations.

“Readmissions have been associated, even before Covid, with worse patient outcomes,” Dr. Mylonakis said.

Some research suggests implications for hospitals currently overwhelmed with cases. A Mount Sinai Hospital study of New York’s first wave found that patients with shorter initial stays and those not sick enough for intensive care were more likely to return within two weeks.

Dr. Lala, who co-wrote the study, said the thinking at overstretched hospitals was “we have a lack of resources, so if the patients are stable get them home.” But, she added, “the fact that length of stay was indeed shorter for those patients who return is begging the question of: Were we kicking these people out the door too soon?”

Many rehospitalized patients have respiratory problems, but some have blood clots, heart trouble, sepsis, gastrointestinal symptoms or other issues, doctors report. Some have neurological symptoms like brain fog, “a clear cognitive issue that is evident when they get readmitted,” said Dr. Vineet Chopra, chief of hospital medicine at the University of Michigan, who co-wrote the Michigan study. “It is there, and it is real.”

Dr. Laurie Jacobs, chairwoman of internal medicine at Hackensack University Medical Center, said causes of readmissions vary.

“Sometimes there’s a lot of push to get patients out of the hospital, and they want to get out of the hospital and sometimes they’re not ready,” so they return, she said. But some appropriately discharged patients develop additional problems or return to hospitals because they lack affordable outpatient care.

Antibiotics and other medications belonging to Mr. Long.
Antibiotics and other medications belonging to Mr. Long.Credit…Emily Rose Bennett for The New York Times

Mr. Long’s ordeal began on March 9. “I couldn’t stand up without falling over,” he said.

His primary physician, Dr. Benjamin Diaczok, immediately told him to call an ambulance.

“I crawled out to the front door,” recalled Mr. Long. He was barefoot and remembers sticking out his arm to prop open the door for the ambulance crew, who found him facedown.

He awoke three days later, in the hospital, when he accidentally pulled out the tubes to the ventilator he’d been hooked up to. After two more days, he’d stabilized enough to return to the apartment where he lives alone, an hour north of Detroit.

Mr. Long had some previous health issues, including blood clots in his lungs and legs several years ago and an irregular heartbeat requiring an implanted heart monitor in 2018. Still, before Covid-19, he was “very high-functioning, very energetic,” Dr. Diaczok said.

Now, Mr. Long said: “I’ve got scarred lungs, pulmonary fibrosis, and I’m running right around 75-to-80 percent lung capacity.”

He was rehospitalized in April, May, June, July, August and September, requiring oxygen and intravenous antibiotics, potassium and magnesium.

“Something must have happened to his lungs that is making them more prone for this,” Dr. Diaczok said.

Mr. Long, a former consultant on tank systems for the military, is also experiencing brain fog that’s forced a hiatus from classes toward a Ph.D. in business convergence strategy.

“I read 10 pages in one of my textbooks and then five minutes later, after a phone call, I can’t remember what I read,” he said.

“It’s horrible, ”Dr. Diaczok said. “This is a man that thinks for a living, and he can’t do his job.”

And his heart arrhythmia, controlled since 2018, has resurfaced. Unless Mr. Long, who is 6-foot-7, sleeps at an incline on his couch, his heart skips beats, causing his monitor to prompt middle-of-the-night calls from his doctor’s office. Unable to lie in bed, “I don’t sleep through the night.”

Small exertions — “just to stand up to go do the dishes” — are exhausting. In July, he tried starting physical therapy but was told he wasn’t ready.

In August, he got up too fast, fell and “I was very confused,” he recalled. During that hospital readmission, doctors noted “altered mental status” from dehydration and treated him for pneumonia and functional lung collapse.

In late October, Mr. Long developed pneumonia again, but under Dr. Diaczok’s guidance, managed at home with high-dose oral antibiotics.

In December, when a pulmonologist administered a breathing test, “I couldn’t make it six seconds,” he said.

Mr. Long repeatedly measures his temperature and pulse oxygen, and can feel in his chest when “trouble’s coming,” he said. Determined to recover, he tries to walk short distances. “Can I make it to take out the trash?” he’ll ask himself. On a good day, he’ll walk eight feet to his mailbox.

“I’m going to be around to walk my daughters down the aisle and see my grandkids,” said Mr. Long, voice cracking. “I’m not going to let this thing win.”

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.”

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Frontline Workers and People Over 74 Should Get Shots Next, CDC Panel Says

Frontline Workers and People Over 74 Should Get Shots Next, CDC Panel Says

The recommendation was a compromise aimed at getting the coronavirus vaccine to the most vulnerable of two high-risk groups.

Director of nursing education Loraine Hopkins Pepe, left, administers the Pfizer BioNTech COVID-19 vaccine to Dr. Richard Fine, head of anesthesiology, at Einstein Medical Center in Philadelphia, PA.
Director of nursing education Loraine Hopkins Pepe, left, administers the Pfizer BioNTech COVID-19 vaccine to Dr. Richard Fine, head of anesthesiology, at Einstein Medical Center in Philadelphia, PA.Credit…Hannah Yoon for The New York Times
  • Dec. 20, 2020, 3:40 p.m. ET

Striking a compromise between two high-risk population groups, a panel advising the Centers for Disease Control and Prevention voted Sunday to recommend that people 75 and older be next in line to receive the coronavirus vaccine in the United States, along with about 30 million “frontline essential workers,” including emergency responders, teachers and grocery store employees.

The debate about who should receive the vaccine in these early months has grown increasingly urgent as the daily tally of cases has swelled to numbers unimaginable even a month ago. The country has already begun vaccinating health care workers, and on Monday, CVS and Walgreens were to begin a mass vaccination campaign at the nation’s nursing homes and long-term care facilities. This week roughly six million doses of the newly authorized Moderna vaccine are to start arriving at more than 3,700 locations around the country, including many smaller and rural hospitals.

The panel of doctors and public health experts had previously indicated it would recommend a much broader group of Americans defined as essential workers — about 87 million people with jobs designated by a division of the Department of Homeland Security as critical to keeping society functioning — as the next priority population and that elderly people who live independently should come later.

But in hours of discussion on Sunday, the committee members concluded that given the limited initial supply of vaccine and the higher Covid-19 death rate among elderly Americans, it made more sense to allow the oldest among them to go next along with workers at the highest risk of exposure to the virus.

Groups of essential workers, such as construction and food service workers, the committee said, would be eligible for the next wave. Members did clarify that local organizations had great flexibility to make those determinations.

“I feel very strongly we do need to have that balance of saving lives and keeping our infrastructure in place,” said Dr. Helen Talbot, a member of the panel and infectious-disease specialist at Vanderbilt University.

Together, the two groups the committee voted to prioritize on Sunday number about 51 million people; federal health officials have estimated that there should be enough vaccine supply to inoculate all of them before the end of February.

Still, as the first week of vaccinations in the U.S. came to a close, frustrations were flaring about the pace of distribution. Some 128,000 shots had been given in the as of Friday, according to a New York Times database tracking vaccinations — a total that was just slightly more than half the number of new cases reported across the country that same day.

This weekend Gen. Gustave F. Perna, who heads the Trump administration’s distribution effort, apologized for more than a dozen states learning at the last minute that they would receive fewer doses next week of the vaccine manufactured by Pfizer than they had expected. Tensions were also broiling in some states over local decisions regarding which health care workers should get their shots immediately and which should wait.

The director of the C.D.C., Dr. Robert Redfield, will review the panel’s recommendation and decide, likely by Monday, whether to embrace it as the agency’s official guidance to states. The panel, the Advisory Committee on Immunization Practices, emphasized that its recommendations were nonbinding and that every state would be able to fine-tune or adjust them to serve the unique needs of its population.

The 13-to-1 vote came as frustrations flared about the pace of vaccine distribution. Some 128,000 shots have been given in the first five days of the vaccine United States, according to a New York Times database tracking vaccinations — just slightly more than half the number of new cases reported across the country on Friday alone. This weekend, Gen. Gustave F. Perna, who heads the Trump administration’s distribution effort, apologized for at least 14 states learning at the last minute that they would receive fewer doses of the vaccine manufactured by Pfizer next week than they had expected. Tensions were also flaring in some states over local decisions regarding which health care workers should get their shots immediately, and which should wait.

In addition to teachers, firefighters and police, a subgroup of the committee suggested that “frontline essential workers” should include school support staff; day care, corrections personnel, public transit, grocery store and postal workers; and those in working in food production and manufacturing. But the group’s official recommendation is not that specific.

Originally, the committee had signaled last month that they had been inclined to let 87 million essential workers receive vaccines ahead of adults 65 and older. Many had expressed their alarm that essential workers, who are often low-wage people of color, were being hit disproportionately hard by the virus and additionally were disadvantaged because of their lesser access to good health care.

general population.”

How Effective Is the Mask You’re Wearing? You May Know Soon

A C.D.C. division is working with an industry standards group to develop filtration standards — and products that meet them will be able to carry labels saying so.

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.”

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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.”

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The Elderly vs. Essential Workers: Who Should Get the Coronavirus Vaccine First?

The Elderly vs. Essential Workers: Who Should Get the Coronavirus Vaccine First?

The C.D.C. will soon decide which group to recommend next, and the debate over the trade-offs is growing heated. Ultimately, states will decide whom to include.

The Department of Homeland Security’s list of essential workers is long and varied, including jobs such as tugboat operators and these grocery store clerks in Brooklyn.
The Department of Homeland Security’s list of essential workers is long and varied, including jobs such as tugboat operators and these grocery store clerks in Brooklyn.Credit…Juan Arredondo for The New York Times
  • Dec. 5, 2020, 10:41 a.m. ET

With the coronavirus pandemic surging and initial vaccine supplies limited, the United States faces a hard choice: Should the country’s immunization program focus in the early months on the elderly and people with serious medical conditions, who are dying of the virus at the highest rates, or on essential workers, an expansive category encompassing Americans who have borne the greatest risk of infection?

Health care workers and the frailest of the elderly — residents of long-term-care facilities — will almost certainly get the first shots, under guidelines the Centers for Disease Control and Prevention issued on Thursday. But with vaccination expected to start this month, the debate among federal and state health officials about who goes next, and lobbying from outside groups to be included, is growing more urgent.

It’s a question increasingly guided by concerns over the inequities laid bare by the pandemic, from disproportionately high rates of infection and death among poor people and people of color to disparate access to testing, child care and technology for online schooling.

“It’s damnable that we are even being placed in this position that we have to make these choices,” said the Rev. William J. Barber II, a co-chairman of the Poor People’s Campaign, a national coalition that calls attention to the challenges of the working poor. “But if we have to make the choice, we cannot once again leave poor and low-wealth essential workers to be last.”

Ultimately, the choice comes down to whether preventing death or curbing the spread of the virus and returning to some semblance of normalcy is the highest priority. “If your goal is to maximize the preservation of human life, then you would bias the vaccine toward older Americans,” Dr. Scott Gottlieb, the former Food and Drug Administration commissioner, said recently. “If your goal is to reduce the rate of infection, then you would prioritize essential workers. So it depends what impact you’re trying to achieve.”

The trade-off between the two is muddied by the fact that the definition of “essential workers” used by the C.D.C. comprises nearly 70 percent of the American work force, sweeping in not just grocery store clerks and emergency responders, but tugboat operators, exterminators and nuclear energy workers. Some labor economists and public health officials consider the category overbroad and say it should be narrowed to only those who interact in person with the public.

Essential and Frontline Occupations

About 70 percent of workers in the U.S. have jobs that are considered essential. A subset are considered “frontline” workers, meaning their jobs cannot be performed from home. Hover or tap to see each job.

Essential

Frontline

By Matthew Conlen·Note: States may have differing definitions of essential workers. | Sources: Labor Market Information Institute, Council for Community and Economic Research, National Bureau of Economic Research, U.S. Bureau of Labor Statistics, Cybersecurity and Infrastructure Security Agency

An independent committee of medical experts that advises the C.D.C. on immunization practices will soon vote on whom to recommend for the second phase of vaccination — “Phase 1b.” In a meeting last month, all voting members of the committee indicated support for putting essential workers ahead of people 65 and older and those with high-risk health conditions.

Historically, the committee relied on scientific evidence to inform its decisions. But now the members are weighing social justice concerns as well, noted Lisa A. Prosser, a professor of health policy and decision sciences at the University of Michigan.

“To me the issue of ethics is very significant, very important for this country,” Dr. Peter Szilagyi, a committee member and a pediatrics professor at the University of California, Los Angeles, said at the time, “and clearly favors the essential worker group because of the high proportion of minority, low-income and low-education workers among essential workers.”

That position runs counter to frameworks proposed by the World Health Organization, the National Academies of Sciences, Engineering, and Medicine, and many countries, which say that reducing deaths should be the unequivocal priority and that older and sicker people should thus go before the workers, a view shared by many in public health and medicine.

Dr. Robert Redfield, the C.D.C. director and the nation’s top public health official, reminded the advisory committee of the importance of older people, saying in a statement on Thursday that he looked forward to “future recommendations that, based on vaccine availability, demonstrate that we as a nation also prioritize the elderly.”

Once the committee votes, Dr. Redfield will decide whether to accept its recommendations as the official guidance of the agency. Only rarely does a C.D.C. director reject a recommendation from the committee, whose 14 members are selected by the Health and Human Services secretary, serve four-and-a-half-year terms and have never confronted a task as high in profile as this one.

But ultimately, the decision will be up to governors and state and local health officials. They are not required to follow C.D.C. guidelines, though historically they have done so.

Defining ‘essential’

The drive-through window at a fast food restaurant in Albuquerque. Food service workers have high rates of infection from the coronavirus.
The drive-through window at a fast food restaurant in Albuquerque. Food service workers have high rates of infection from the coronavirus.Credit…Adria Malcolm for The New York Times

There are about 90 million essential workers nationwide, as defined by a division of the Department of Homeland Security that compiled a roster of jobs that help maintain critical infrastructure during a pandemic. That list is long, and because there won’t be enough doses to reach everyone at first, states are preparing to make tough decisions: Louisiana’s preliminary plan, for example, puts prison guards and food processing workers ahead of teachers and grocery employees. Nevada’s prioritizes education and public transit workers over those in retail and food processing.

Share of workers in essential and frontline jobs, by state

By Matthew Conlen·Note: States may have different definitions of essential workers. | Sources: Labor Market Information Institute, Council for Community and Economic Research, National Bureau of Economic Research, U.S. Bureau of Labor Statistics, Cybersecurity and Infrastructure Security Agency

At this early point, many state plans put at least some people who are older and live independently, or people who have medical conditions, ahead of most essential workers, though that could change after the C.D.C. committee makes a formal recommendation on the next phase.

One occupation whose priority is being hotly debated is teaching. The C.D.C. includes educators as essential workers. But not everyone agrees with that designation.

Marc Lipsitch, an infectious-disease epidemiologist at Harvard’s T.H. Chan School of Public Health, argued that teachers should not be included as essential workers, if a central goal of the committee is to reduce health inequities.

“Teachers have middle-class salaries, are very often white, and they have college degrees,” he said. “Of course they should be treated better, but they are not among the most mistreated of workers.”

Elise Gould, a senior economist at the Economic Policy Institute, disagreed. Teachers not only ensure that children don’t fall further behind in their education, she said, but are also critical to the work force at large.

An empty classroom in Ohio. Public health experts disagree on whether teachers should get a top priority for the vaccine.Credit…Kyle Grillot/Reuters

“When you talk about disproportionate impact and you’re concerned about people getting back into the labor force, many are mothers, and they will have a harder time if their children don’t have a reliable place to go,” she said. “And if you think generally about people who have jobs where they can’t telework, they are disproportionately Black and brown. They’ll have more of a challenge when child care is an issue.”

In September, academic researchers analyzed the Department of Homeland Security’s list of essential workers and found that it broadly mirrored the demographics of the American labor force. The researchers proposed a narrower, more vulnerable category — “frontline workers,” such as food deliverers, cashiers and emergency medical technicians, who must work face to face with others and are thus at greater risk of contracting the virus.

By this definition, said Francine D. Blau, a labor economist at Cornell University and an author of the study, teachers belong in the larger category of essential workers. However, when they work in classrooms rather than remotely, she said, would they fit into the “frontline” group. Individual states categorize teachers differently.

Dr. Blau said that if supplies are short, frontline workers should be emphasized. “These are a subset of essential workers who, given the nature of their jobs, must provide their labor in person. Prioritizing them makes sense given the heightened risk that they face.”

The analysis, a working paper for the National Bureau of Economic Research, is in line with other critics, who say that the list of essential workers is too wide-ranging.

“If groups are too large, then you’re not really focusing on priorities,” said Saad B. Omer, director of the Yale Institute for Global Health, who worked on the vaccination frameworks for the W.H.O. and the National Academies.

The essential workers on the federal list make up nearly 70 percent of the American labor force, the researchers said, compared with 42 percent for the frontline workers. Women made up 39 percent of frontline workers and, in certain occupations, far more. Frontline workers’ education levels are lower, as are their wages — on average, just under $22 an hour. The proportion of Black and Hispanic workers is higher than in the broader category of essential workers.

Death vs. transmission

A nursing home resident in Brooklyn being taken to a hospital last April. The C.D.C. recommends that residents of long-term care facilities, along with health care workers, get the very first vaccines.Credit…Lucas Jackson/Reuters

Some health policy experts said that to prioritize preventing deaths rather than reducing virus transmission was simply a pragmatic choice, because there won’t be enough vaccine initially available to make a meaningful dent in contagion. A more effective use of limited quantities, they say, is to save the lives of the most frail.

Moreover, vaccine trial results so far show only that the shots can protect the individuals who receive them. The trials have not yet demonstrated that a vaccinated person would not infect others. Though scientists believe that is likely to be the case, it has yet to be proved.

Harald Schmidt, an expert in ethics and health policy at the University of Pennsylvania, said that it is reasonable to put essential workers ahead of older adults, given their risks, and that they are disproportionately minorities. “Older populations are whiter, ” Dr. Schmidt said. “Society is structured in a way that enables them to live longer. Instead of giving additional health benefits to those who already had more of them, we can start to level the playing field a bit.”

But to protect older people more at risk, he called on the C.D.C. committee to also integrate the agency’s own “social vulnerability index.”

The index includes 15 measures derived from the census, such as overcrowded housing, lack of vehicle access and poverty, to determine how urgently a community needs health support, with the goal of reducing inequities.

In a new analysis of the states’ preliminary vaccine plans, Dr. Schmidt found that at least 18 states intended to apply the index. Tennessee, for one, has indicated that it will reserve some of its early allotments for disadvantaged communities.

Still, some people believe it is wrong to give racial and socioeconomic equity more weight than who is most likely to die.

“They need to have bombproof, fact-based, public-health-based reasons for why one group goes ahead of another,” said Chuck Ludlam, a former Senate aide and biotech industry lobbyist who protested putting essential workers ahead of older people in comments to the committee. “They have provided no explanation here that will withstand public scrutiny.”

Blurred lines, many unknowns

Employees of the Four Seasons Rehabilitation and Nursing in Westland, Mich., demonstrated for better pay and protections during an outbreak of Covid-19 in October.Credit…Emily Elconin/Reuters

Further complicating matters, the different priority groups discussed by the C.D.C. committee are overlapping — many essential workers have high-risk conditions, and some are older than 65. Some states have suggested that they will prioritize only essential workers who come face to face with the public, while others have not prioritized them at all.

Even some people whose allegiance lies with one group have made the case that others should have an earlier claim on the vaccine. Marc Perrone, president of the United Food and Commercial Workers Union, which represents 1.3 million grocery and food processing workers, said that despite the high rate of infection among his members, he thought that older adults should go first.

“Here’s the thing: Everybody’s got a grandmother or grandfather,” Mr. Perrone said. “And I do believe almost everybody in this country would want to protect them, or their aging parents.”

But Dr. Nirav Shah, Maine’s top public health official, said he respectfully disagreed, repeating the explanation he had given his in-laws — who are older but in good health and able to socially distance.

He said: “I’ve told them: ‘You know what? I’m sorry, but there are others that I need to get this vaccine to first, so that when you guys get vaccinated, the world you come back into is ready to receive you.’”

All these plans are, of course, unfurling with essential information still unknown.Many state officials said that as on-the-ground realities emerge, they fully expect their plans to evolve.

One uncertainty: given the high rates of apprehension swirling around this vaccine, how many people in the early groups will actually line up for it?

“If a high proportion of essential workers decline to get the vaccine, states will have to quickly move onto the next group anyway,” said Dr. Prosser, the University of Michigan health analyst. “Because once the vaccines arrive, they will have to be used in a certain amount of time before they degrade.”

Additional work by Jugal K. Patel.

C.D.C. Officials Shorten Recommended Quarantine Periods

C.D.C. Officials Shorten Recommended Quarantine Periods

The agency also urged Americans to stay home during the coming holidays, and to get tested if they do travel.

Signage on California’s Highway 99 advised people to stay home to avoid Covid-19 last month.
Signage on California’s Highway 99 advised people to stay home to avoid Covid-19 last month.Credit…Peter Dasilva/EPA, via Shutterstock
Roni Caryn Rabin

By

  • Dec. 2, 2020, 5:03 p.m. ET

Federal health officials on Wednesday effectively shortened quarantine periods for those who may have been exposed to the coronavirus, hoping to improve compliance among Americans and reduce the economic and psychological toll of long periods of seclusion.

Citing the spiraling number of infections nationwide, officials at the Centers for Disease Control and Prevention also urged Americans again to avoid travel over the holiday season.

“The C.D.C. recommends the best way to protect yourself and others is to postpone travel and stay home,” Dr. Henry Walke, who oversees day-to-day management of pandemic response at the agency, said at a news briefing.

People who choose to travel over the holiday season despite the warnings should consider getting tested for coronavirus infection one to three days before their trip, and again three to five days after return, Dr. Walke and other officials said.

It is the first time the agency has urged testing for domestic travelers; until now, testing was recommended only for Americans traveling internationally. Dr. Walke noted that testing before and after travel “does not eliminate all risk.”

Travelers returning home should keep nonessential activities to a minimum for at least seven days if they are getting tested, and for 10 days if they are not getting tested. (Many states already require travelers to self-quarantine after arrival, though the rules vary from state to state.)

Federal health officials also offered two new ways to shorten quarantine periods. Those without symptoms may end quarantine after seven days if they are tested for the virus and receive a negative result, or after 10 days without a negative test.

P.C.R. or rapid tests are both acceptable, the officials said, and should be taken within 48 hours of the end of the quarantine period. People should continue to watch for symptoms for 14 days.

(Quarantine refers to people who are well but may become ill; isolation refers to those known to be ill.)

Until now, the C.D.C. has recommended a 14-day quarantine period following potential exposure, and Dr. Walke stressed that the full two weeks is still considered ideal and the surest way to curb transmissions.

While a shortened quarantine period may be more palatable to Americans, officials acknowledged that the new guidance might lead to some infections being missed.

“We can safely reduce the length of quarantine, but accepting that there is a small residual risk that a person who is leaving quarantine early could transmit to someone else if they became infected,” said Dr. John Brooks, the chief medical officer for the Covid-19 response at the C.D.C.

Some patients may not develop symptoms until two weeks after exposure, and even longer in a very small fraction of cases. Infected individuals may pass the virus to others before they develop symptoms; recent studies show they are most infectious two days before symptoms begin, and for about five days afterward.

The new recommendations do not have the force of law. Federal officials share them with state and county public health agencies, who make their own determinations based on local conditions and needs.

The agency’s warnings against holiday travel echoed those issued just a week before Thanksgiving. Millions of Americans hit the road nonetheless to spend the holiday with friends and family, though the number of travelers was lower than in a typical year.

“Cases are rising, hospitalizations are increasing, deaths are increasing,” Dr. Walke said. “We need to try to bend the curve, stop this exponential increase.”

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Dr. Cindy Friedman, chief of the travelers health branch at the C.D.C., said the agency was reiterating the message further in advance of the Christmas holiday to provide more time for people to plan ahead, “think about the safest option for them and their families” and make “tough choices.”

“We know it’s a hard decision, and people need time to prepare and have discussions with family and friends and to make these decisions,” Dr. Friedman added. Even a small percentage of infected travelers could “translate into hundreds of thousands of additional infections.”

Hospitals are already overwhelmed in many regions, as cases have been rising rapidly, with the country adding over a million new infections during a recent one-week period, according to data maintained by The New York Times.

Daily deaths have been exceeding 2,000 for the first time since early May, and close to 100,000 Americans are already hospitalized.

“We are at the point now, even before Christmas, that there may not be room at your hospital, because we don’t have enough health care workers to take care of you,” said Michael Osterholm, a member of President-elect Joseph R. Biden Jr.’s Covid-19 advisory board, who also urged Americans to stay home.

Long-Term-Care Residents and Health Workers Should Get Vaccine First, C.D.C. Panel Says

BREAKING

Long-Term-Care Residents and Health Workers Should Get Vaccine First, C.D.C. Panel Says

The C.D.C. director will decide by Wednesday whether to accept the recommendation. States aren’t required to follow it, but most are expected to.

Medics in Austin, Texas, on a call to a nursing home earlier this year. The C.D.C. panel voted to urge vaccinating of nursing home residents and health care workers first.
Medics in Austin, Texas, on a call to a nursing home earlier this year. The C.D.C. panel voted to urge vaccinating of nursing home residents and health care workers first.Credit…John Moore/Getty Images
Abby Goodnough

By

  • Dec. 1, 2020, 6:03 p.m. ET

WASHINGTON — An independent panel advising the Centers for Disease Control and Prevention voted Tuesday to recommend that residents and employees of nursing homes and similar facilities be the first people in the United States to receive coronavirus vaccines, along with health care workers who are especially at risk of being exposed to the virus.

The panel, the Advisory Committee on Immunization Practices, voted 13 to 1 during an emergency meeting to make the recommendation. The director of the C.D.C., Dr. Robert R. Redfield, is expected to decide by Wednesday whether to accept it as the agency’s formal guidance to states as they prepare to start giving people the shots as soon as two weeks from now.

“We are acting none too soon,” said Dr. Beth Bell, a panel member and global health expert at the University of Washington, noting that Covid-19 would kill about 120 Americans during the meeting alone.

States are not required to follow the panel’s recommendations, but they usually do. The final decision will rest with governors, who are consulting with their top health officials as they complete distribution plans.

The new recommendation is the first of several expected from the panel over the coming weeks, as vaccines developed by Pfizer and Moderna go through the federal approval process, on the thorny question of which Americans should be at the front of the long line to get vaccinated while supply is still scarce. The panel described it as an interim recommendation that could change as more is learned about how well the vaccines work in different age groups and how well the manufacturers keep up with demand.

The roughly three million people living in long-term care and those who care for them are a relatively clear target; 39 percent of deaths from the coronavirus have occurred in such facilities, according to an analysis by The New York Times. But states and health systems will ultimately have to decide which of the nation’s 21 million health care workers should qualify to receive the first doses, as there won’t be enough at first for everyone.

Pfizer and Moderna have estimated that they will have enough to vaccinate, at most, 22.5 million Americans by year’s end, with the required two doses, a few weeks apart. The C.D.C. will apportion the supply among the states, with the initial allocation proportional to the size of each state’s adult population.

The only member of the committee to vote against the recommendation was Dr. Helen Talbot, an infectious-disease specialist at Vanderbilt University, who expressed discomfort with putting long-term-care residents in the first priority group because the vaccines’ safety had not been studied in that particular population. “We enter this realm of ‘we hope it works and we hope it’s safe,’ and that concerns me on many levels,” she said before the vote.

But most panel members who offered opinions said they thought the high death rate among that group made it imperative to include it.

Dr. José Romero, the chairman of the panel, said that he felt strongly that its process had adhered to its core principles: “maximizing benefit and minimizing harm,” promoting justice and addressing health inequities. Dr. Beth Bell, the co-chair, acknowledged that all of the members would have liked more data from clinical trials but said that because of the pandemic emergency, “we need to act.”

The panel, whose 14 voting members have expertise in vaccinology, immunology, virology, public health and other relevant fields, has hinted that the next priority group it will recommend for vaccination — “Phase 1b” — will be so-called essential workers, a huge group numbering more than 85 million. A division of the Department of Homeland Security has come up with a list of workers states should consider counting in that group; it includes teachers and others who work in schools, emergency responders, police officers, grocery workers, corrections officers, public transit workers and others whose jobs make it hard or impossible to work from home.

Dr. Robert Redfield, the C.D.C. director, during an October briefing at the agency’s headquarters in Atlanta.
Dr. Robert Redfield, the C.D.C. director, during an October briefing at the agency’s headquarters in Atlanta.Credit…Jenni Girtman/EPA, via Shutterstock

After essential workers, the committee is leaning toward recommending vaccination of adults with medical conditions that put them at high risk of coronavirus infection, such as diabetes or obesity, and everyone over 65. But some states might diverge to an extent, possibly choosing, for example, to vaccinate residents over 75 and then some types of essential workers.

All other adults would follow the initial groups. The vaccine has not yet been thoroughly studied in children, so people under 18 would not be eligible yet.

For at least a month or two, there will not be nearly enough vaccine to cover everyone in the initial groups. Dr. Moncef Slaoui, who leads the Trump administration’s Operation Warp Speed, said Tuesday morning in an interview with The Washington Post that Pfizer and Moderna would be able to provide an additional 60 to 70 million doses in January “if all goes well.” Since each person gets two shots, that would only be enough for 55 million people at most through the end of January — about 22 percent of the nation’s roughly 255 million adults.

Production will continue to increase in February and March, Dr. Slaoui said, with the hope that two new vaccines, from AstraZeneca and Johnson & Johnson, will gain F.D.A. approval.

“So very quickly, we start having more than 150 million doses a month in March, April, May,” he added. He and other federal officials have said that the general public is likely to be able to be vaccinated by May or June.

The C.D.C. panel was originally not supposed to vote on its recommendations until after the F.D.A. had approved a vaccine. But it bumped up the timing to give states more guidance as they complete their distribution plans, which must be submitted to the C.D.C. on Friday.

On Tuesday, the group specifically suggested that within the long-term-care population, residents of nursing homes, who tend to be the most frail and susceptible to Covid, should get the first vaccines in the event that there aren’t enough, along with staff members who have not had the virus within the last 90 days.

Within the much larger category of health care workers, the panel said that health systems should consider prioritizing those who have direct contact with patients and their families and those who handle infectious materials. Dr. Nancy Messonnier, who leads the C.D.C.’s National Center for Immunization and Respiratory Diseases, told the panel that based on her recent conversations with state health officials, most states and large cities “believe they can vaccinate all of their health care workers within three weeks.”

But whether they reach that goal depends on how much vaccine they get, and how quickly. Gov. Andy Beshear of Kentucky told reporters on Monday that his state had more than 200,000 health care workers but would receive only 38,000 doses in its first shipment and that it might not get another for two weeks.

Long-term-care facilities include nursing homes, with about 1.3 million residents; assisted-living facilities, with 800,000 residents; and residential care facilities, which tend to be small and cater to specific populations. The federal government has contracted with CVS and Walgreens to deliver vaccines to most such facilities nationwide, with teams of pharmacists making three visits to each to ensure that every staff member and resident gets both an initial shot and a booster shot several weeks later.

Several members of the panel urged that small community doctors’ offices not be left off the initial priority list. “Transmission dynamics suggest providers who care for patients earlier in their course of illness may be at higher risk,” said Dr. Jeffrey Duchin, a member of the panel who is in charge of public health in Seattle and King County, Wash.

Dr. Grace Lee, a panel member and a pediatrics professor at Stanford, said special attention should be paid to health care workers in lower-paying positions, such as nursing assistants, food workers and janitors, who may fear for their job security if they push to secure a spot toward the front of the vaccination line.

I am very mindful of the equity concerns,” Dr. Lee said.

Jan Hoffman contributed reporting.

Who Will Get the Coronavirus Vaccine First?

After months of deliberation and debate, a panel of independent experts advising the Centers for Disease Control and Prevention is set to decide on Tuesday which Americans it will recommend to get the coronavirus vaccine first, while supply is still short.

The panel, the Advisory Committee on Immunization Practices, will vote in a public meeting on Tuesday afternoon, and it is expected to advise that health care workers be first in line, along with residents of nursing homes and other long-term care facilities. If the C.D.C. director, Dr. Robert R. Redfield, approves the recommendations, they will be shared with states, which are preparing to receive their first vaccine shipments as soon as mid-December, if the Food and Drug Administration approves an application for emergency use of a vaccine developed by Pfizer.

States don’t have to follow the C.D.C.’s recommendations, but most probably will, said Dr. Marcus Plescia, the chief medical officer for the Association of State and Territorial Health Officials, which represents state health agencies. The committee will meet again soon to vote on which groups should be next to receive priority.

Here are answers to some common questions about the vaccine and its distribution.

Who will get the vaccine first?

Based on its recent discussions, the C.D.C. committee will almost certainly recommend that the nation’s 21 million health care workers be eligible before anyone else, along with three million mostly elderly people living in nursing homes and other long-term care facilities.

A staggering 39 percent of deaths from the coronavirus have occurred in long-term care facilities, according to the committee. But there won’t be enough doses at first to vaccinate everyone in these groups; Pfizer and Moderna, the two companies closest to gaining approval for their vaccines, have estimated that they will have enough to vaccinate no more than 22.5 million Americans by January. So each state will have to decide which health care workers go first.

They may choose to prioritize critical care doctors and nurses, respiratory therapists and other hospital employees, including cleaning staff, who are most likely to be exposed to the coronavirus. Or they may offer the vaccine to older health care workers first, or those working in nursing homes, who are at higher risk of contracting the virus. Gov. Andy Beshear of Kentucky said on Monday that most of his state’s initial allocation would go to residents and employees of long-term care facilities, with a smaller amount going to hospital workers.

It’s important to remember that everyone who gets a vaccine made by Pfizer or Moderna will need a second shot — three weeks later for Pfizer’s, four weeks for Moderna’s.

Who gets it next?

The C.D.C. committee hinted last week that it would recommend essential workers be next in line. About 87 million Americans work in food and agriculture, manufacturing, law enforcement, education, transportation, corrections, emergency response and other sectors. They are at increased risk of exposure to the virus because their jobs preclude them from working from home. And these workers are disproportionately Black and Hispanic, populations that have been hit especially hard by the virus.

Individual states may decide to include in this group employees of industries that have been particularly affected by the virus. Arkansas, for example, has proposed including workers in its large poultry industry, while Colorado wants to include ski industry workers who live in congregate housing.

After essential workers, the priority groups likely to be recommended by the C.D.C. committee are adults with medical conditions that put them at high risk of coronavirus infection, and people over 65. But again, some states might diverge to an extent, choosing, for example, to vaccinate residents over 75 before some types of essential workers. All other adults would follow. The vaccine has not yet been thoroughly studied in children, so they would not be eligible yet.

If the C.D.C. director, Dr. Robert R. Redfield, approves the panel’s recommendations, they will be shared with states.
If the C.D.C. director, Dr. Robert R. Redfield, approves the panel’s recommendations, they will be shared with states.Credit…Stefani Reynolds for The New York Times

Who will make state-level decisions about priority groups?

Each state has a working group, composed largely of public health officials, that has been planning for months and making decisions about vaccination campaigns. Each state’s top health official and governor will probably sign off on final plans.

How long will states focus on one priority group before moving to the next in line?

States don’t need to reach everyone in one priority group before moving on to the next, according to the C.D.C. advisory committee. But more federal guidance is expected on the subject.

When will the first doses of a vaccine be shipped, and where will they go?

Federal officials have said they plan to ship the first 6.4 million doses within 24 hours after the F.D.A. authorizes a vaccine, and the number each state receives will be based on a formula that considers its adult population. Pfizer will ship special coolers, each containing at least 1,000 doses, directly to locations determined by each state’s governor. At first, almost all of those sites will probably be hospitals that have confirmed they can store shipments at minus 94 degrees Fahrenheit, as the Pfizer vaccine requires, or use them quickly.

When will a vaccine be available to the general public, and where will people receive it?

Federal officials have repeatedly suggested that people who are not in the priority groups — healthy adults under 65 who don’t work in health care or otherwise qualify as essential workers — should have access to the vaccine by May or June, because there will be enough supply by then. But a lot will have to go right for that to happen. One factor is whether, or when, other vaccines besides Pfizer’s and Moderna’s are approved.

Can employers like hospitals or grocery stores require their employees to be vaccinated?

Employers do have the right to compel their workers to be vaccinated. Many hospital systems, for example, require annual flu shots. But employees can seek exemptions based on medical reasons or religious beliefs. In such cases, employers are supposed to provide a “reasonable accommodation”; with a coronavirus vaccine, a worker might be allowed to wear a mask in the office instead, or to work from home.

Three companies have announced preliminary data indicating their vaccines are effective, and there are dozens of additional candidates in clinical trials. Can I choose which vaccine I get?

This depends on a number of factors, including the supply in your area at the time you’re vaccinated and whether certain vaccines are found to be more effective in certain populations, such as older adults. At first, the only choice is likely to be Pfizer’s vaccine, assuming it is approved. Moderna asked the F.D.A. for emergency authorization on Monday; if approved, it would most likely become available within weeks after Pfizer’s.

Are there any side effects from the shot?

Some participants in both Pfizer’s and Moderna’s trials have said they experienced symptoms including fever, muscle aches, bad headaches and fatigue after receiving the shots, but the side effects generally did not last more than a day. Still, preliminary data suggests that, compared with most flu vaccines, the coronavirus shots have a somewhat higher rate of such reactions, which are almost always normal signs that the body’s immune response is kicking in. At the meeting of the C.D.C. advisory committee last week, some members said it would be important for doctors to warn their patients about possible side effects and assure them of the vaccines’ safety.

How do I know it’s safe?

Each company’s application to the F.D.A. includes two months of follow-up safety data from Phase 3 of clinical trials conducted by universities and other independent bodies. In that phase, tens of thousands of volunteers get a vaccine and wait to see if they become infected, compared with others who receive a placebo. By September, Pfizer’s trial had 44,000 participants; no serious safety concerns have been reported.

The F.D.A. will also review the data for each vaccine seeking authorization and share it with its advisory committee, which will meet publicly — in the case of the Pfizer vaccine, on Dec. 10 — to ask questions and make a recommendation to the agency. The F.D.A. will then decide whether to approve the vaccine for emergency use.

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Should Isolation Periods Be Shorter for People With Covid-19?

People with Covid-19, the illness caused by the coronavirus, are most infectious about two days before symptoms begin and for five days afterward, according to a new analysis of previous research.

A few patients who are extremely ill or have impaired immune systems may expel — or “shed” — the virus for as long as 20 days, other studies have suggested. Even in mild cases, some patients may shed live virus for about a week, the new analysis found.

The accumulating data presents a quandary: Should public health officials shorten the recommended isolation time if it means more infected people will cooperate? Or should officials opt for longer periods in order to prevent transmission in virtually all cases, even if doing so takes a harsher toll on the economy?

The Centers for Disease Control and Prevention recommends that infected people isolate for a minimum of 10 days from the beginning of their illness. The agency is considering shortening the recommended isolation period and may issue new guidelines as early as next week, according to two federal officials with knowledge of the discussions.

In September, France dropped its required period of isolation to seven days from 14 days, and Germany is considering shortening it to five days. (Isolation refers to people who are ill; quarantine refers to people who have been exposed to the virus and may become ill.)

Setting the isolation period at five days is likely to be much more palatable and may encourage more infected people to comply, said Dr. Muge Cevik, an infectious disease expert at the University of St Andrews in Scotland who led the new analysis, published in the journal The Lancet Microbe.

A recent survey in the United Kingdom showed that only one in five people were able to isolate for 10 days after developing symptoms. “Even if we do more testing, if we can’t ensure people self-isolate, I don’t think we’ll be able to control the spread,” Dr. Cevik said.

In the United States, many people don’t get tested for the infection until a day or two after they begin to feel ill. With the current delays, many receive results two or three days later, toward the end of the period during which they are infectious.

“Even if you were to get the P.C.R. test right on the very first day that you could, by the time you get the results back, 90 percent of your shedding has been completed,” said Dr. Michael Mina, a virologist at the Harvard T.H. Chan School of Public Health. “This meta-analysis shows just how short your transmission window is.”

Dr. Cevik and her colleagues set out to analyze the so-called kinetics of the coronavirus over the course of an infection, and to compare the pathogen to the closely related SARS and MERS viruses.

The researchers considered nearly 1,500 studies published from 2003 to June 2020 on the timing of infection in thousands of people, most of whom were sick enough to be hospitalized. The team drew data from 79 studies of the new coronavirus, 11 studies of MERS and eight studies of SARS.

People who never develop symptoms seem to carry about the same amount of the new coronavirus as symptomatic patients, Dr. Cevik and her colleagues found. But asymptomatic people seem to clear the virus more quickly from their bodies.

People with Covid-19 usually are most infectious a day or two before the onset of symptoms until about five days after, the analysis concluded. Yet patients may carry genetic fragments from the virus in their noses and throats for an average of 17 days, and, in some cases, for up to three months.

A few patients may carry infectious virus in their lungs — as opposed to the nose and throat — for as long as eight days after symptoms begin, noted Dr. Megan Ranney, an emergency physician at Brown University. For these patients, at least, isolation periods should probably be longer than five days, if only they could be identified.

“The trouble is, who has Covid pneumonia versus who doesn’t is not always fully apparent just based on physical exam,” she said. “They wouldn’t know it on their own.”

Older people tend to be infectious for longer than younger people, but no study in the analysis detected live virus beyond nine days of symptom onset. The results suggest that positive tests after that point find only genetic fragments, rather than whole live virus, Dr. Cevik said.

Because the infectious period seems to peak relatively quickly in the course of the illness, health care workers at community clinics may be at higher risk of becoming infected than those working in I.C.U. units, where patients tend to be in the later stages, Dr. Cevik added.

The analysis underscores data that have accumulated since March. In July, based on similar evidence, the C.D.C. truncated its recommendation for isolation to 10 days from 14 days.

But even at 10 days, the isolation period may be too long for many people, experts said. Patients may be financially unable to isolate for so long, or they may not feel sick enough to want to do so.

“If you could make that shorter for people, I think that would really help people comply with the public health guidelines,” said Angela Rasmussen, a virologist affiliated with the Center for Global Health Science and Security at Georgetown University, referring to the recommended isolation period.

But the new analysis is limited by the fact that only a few of the included studies looked at live virus, she added.

Some people who are older or very sick may be infectious for longer than a week. But if a shorter recommended period encourages more people to isolate, the benefit will more than offset any risk to the community from the small amount of virus that a few patients may still carry after five days, said Dr. Stefan Baral, an epidemiologist at Johns Hopkins University.

But some doctors said that they were not convinced by the analysis that five days of isolation would prevent transmission from a majority of people.

“There’s a sweet spot there, I would imagine, but I haven’t figured out where that is,” said Dr. Taison Bell, a critical care and infectious disease physician at the University of Virginia.

Dr. Cevik and other experts suggest that people can isolate as soon as they experience even mild symptoms, such as a sore throat or head and body aches — without venturing out for a P.C.R. test right when they are most infectious.

But Dr. Bell said he was unsure how this would work in practice, because these early symptoms were similar to those from other viral infections, including the common cold.

Dr. Cevik said a P.C.R. test should be performed after isolation ended, to confirm the diagnosis. Alternately, it may make sense to take a rapid antigen test — which can detect high amounts of virus — while isolating, to confirm an active coronavirus infection.

Other experts also endorsed the use of at-home rapid tests. “I think that’s a lovely solution,” Dr. Ranney said. “If you have symptoms, and you have a reliable test that you can do at home, stay home, test at home and isolate for five days.”

Over all, the new analysis underscores how quickly the coronavirus blooms in the body and the speed with which both patients and doctors must respond to keep it contained, Dr. Baral said. Levels of the MERS virus peak at seven to 10 days from symptom onset, and those of the SARS virus peak at Days 10 to 14.

By contrast, the new coronavirus “moves quick,” Dr. Baral said. “It’s a very difficult virus to control, as compared to SARS.”

Home isolation is safe for most of those newly infected with the coronavirus, he added — essentially the model of care that doctors use for patients suspected of having influenza.

Some countries already have adopted policies to make it easier for people to isolate. Vietnam provides income support to people who need to take time off work. Until May, the Japanese government asked patients who were young and had mild symptoms to stay home for four days before seeking testing.

Japan’s guidelines now ask patients to consult by phone with their doctors and to seek testing only if they seem likely to be infected. Anyone who tests positive is admitted to a hospital or a hotel to isolate. In the United States, New York City and Vermont have made similar accommodations available to infected patients.

Even if the rest of the country doesn’t implement such policies, having patients isolate at home — while wearing a mask, keeping windows open, cleaning high-touch surfaces and staying far from other household members — is more feasible for five days than for 10, Dr. Baral said.

“I do think there’s an element of diminishing returns with those last four or five days,” he said. “An intense amount of isolation during that first five to seven days would avert a ton of infections — a ton.”

Makiko Inoue contributed reporting from Tokyo.