A series of studies found that the Moderna vaccine seemed to be more protective over the long term than the Pfizer-BioNTech vaccine. Here’s why.It was a constant refrain from federal health officials after the coronavirus vaccines were authorized: These shots are all equally effective.That has turned out not to be true.Roughly 221 million doses of the Pfizer-BioNTech vaccine have been dispensed thus far in the United States, compared with about 150 million doses of Moderna’s vaccine. In a half-dozen studies published over the past few weeks, Moderna’s vaccine appeared to be more protective over the long term than the Pfizer-BioNTech vaccine.Research published on Friday by the Centers for Disease Control and Prevention found that the efficacy of the Pfizer-BioNTech vaccine against hospitalization fell from 91 percent to 77 percent after a four-month period following the second shot. The Moderna vaccine showed no decline over the same period.If the efficacy gap continues to widen, it may have implications for the debate on booster shots. Federal agencies this week are evaluating the need for a third shot of the Pfizer-BioNTech vaccine for some high-risk groups, including older adults.Scientists who were initially skeptical of the reported differences between the Moderna and Pfizer-BioNTech vaccines have slowly become convinced that the disparity is small but real.“Our baseline assumption is that the mRNA vaccines are functioning similarly, but then you start to see a separation,” said Natalie Dean, a biostatistician at Emory University in Atlanta. “It’s not a huge difference, but at least it’s consistent.”But the discrepancy is small and the real-world consequences uncertain, because both vaccines are still highly effective at preventing severe illness and hospitalization, she and others cautioned.“Yes, likely a real difference, probably reflecting what’s in the two vials,” said John Moore, a virologist at Weill Cornell Medicine in New York. “But truly, how much does this difference matter in the real world?”“It’s not appropriate for people who took Pfizer to be freaking out that they got an inferior vaccine.”Even in the original clinical trials of the three vaccines eventually authorized in the United States — made by Pfizer-BioNTech, Moderna and Johnson & Johnson — it was clear that the J.&J. vaccine had a lower efficacy than the other two. Research since then has borne out that trend, although J.&J. announced this week that a second dose of its vaccine boosts its efficacy to levels comparable to the others.The Pfizer-BioNTech and Moderna vaccines rely on the same mRNA platform, and in the initial clinical trials, they had remarkably similar efficacy against symptomatic infection: 95 percent for Pfizer-BioNTech and 94 percent for Moderna. This was in part why they were described as more or less equivalent.The subtleties emerged over time. The vaccines have never been directly compared in a carefully designed study, so the data indicating that effects vary are based mostly on observations.Results from those studies can be skewed by any number of factors, including the location, the age of the population vaccinated, when they were immunized and the timing between the doses, Dr. Dean said.For example, the Pfizer-BioNTech vaccine was rolled out weeks before Moderna’s to priority groups — older adults and health care workers. Immunity wanes more quickly in older adults, so a decline observed in a group consisting mostly of older adults may give the false impression that the protection from the Pfizer-BioNTech vaccine falls off quickly.Given those caveats, “I’m not convinced that there truly is a difference,” said Dr. Bill Gruber, a senior vice president at Pfizer. “I don’t think there’s sufficient data out there to make that claim.”But by now, the observational studies have delivered results from a number of locations — Qatar, the Mayo Clinic in Minnesota, several other states in the United States — and in health care workers, hospitalized veterans or the general population.Moderna’s efficacy against severe illness in those studies ranged from 92 to 100 percent. Pfizer-BioNTech’s numbers trailed by 10 to 15 percentage points.The two vaccines have diverged more sharply in their efficacy against infection. Protection from both waned over time, particularly after the arrival of the Delta variant, but the Pfizer-BioNTech vaccine’s values fell lower. In two of the recent studies, the Moderna vaccine did better at preventing illness by more than 30 percentage points.A few studies found that the levels of antibodies produced by the Pfizer-BioNTech vaccine were one-third to one-half those produced by the Moderna vaccine. Yet that decrease is trivial, Dr. Moore said: For comparison, there is a more than 100-fold difference in the antibody levels among healthy individuals..css-1xzcza9{list-style-type:disc;padding-inline-start:1em;}.css-3btd0c{font-family:nyt-franklin,helvetica,arial,sans-serif;font-size:1rem;line-height:1.375rem;color:#333;margin-bottom:0.78125rem;}@media (min-width:740px){.css-3btd0c{font-size:1.0625rem;line-height:1.5rem;margin-bottom:0.9375rem;}}.css-3btd0c strong{font-weight:600;}.css-3btd0c em{font-style:italic;}.css-w739ur{margin:0 auto 5px;font-family:nyt-franklin,helvetica,arial,sans-serif;font-weight:700;font-size:1.125rem;line-height:1.3125rem;color:#121212;}#NYT_BELOW_MAIN_CONTENT_REGION .css-w739ur{font-family:nyt-cheltenham,georgia,’times new roman’,times,serif;font-weight:700;font-size:1.375rem;line-height:1.625rem;}@media (min-width:740px){#NYT_BELOW_MAIN_CONTENT_REGION .css-w739ur{font-size:1.6875rem;line-height:1.875rem;}}@media (min-width:740px){.css-w739ur{font-size:1.25rem;line-height:1.4375rem;}}.css-9s9ecg{margin-bottom:15px;}.css-16ed7iq{width:100%;display:-webkit-box;display:-webkit-flex;display:-ms-flexbox;display:flex;-webkit-align-items:center;-webkit-box-align:center;-ms-flex-align:center;align-items:center;-webkit-box-pack:center;-webkit-justify-content:center;-ms-flex-pack:center;justify-content:center;padding:10px 0;background-color:white;}.css-pmm6ed{display:-webkit-box;display:-webkit-flex;display:-ms-flexbox;display:flex;-webkit-align-items:center;-webkit-box-align:center;-ms-flex-align:center;align-items:center;}.css-pmm6ed > :not(:first-child){margin-left:5px;}.css-5gimkt{font-family:nyt-franklin,helvetica,arial,sans-serif;font-size:0.8125rem;font-weight:700;-webkit-letter-spacing:0.03em;-moz-letter-spacing:0.03em;-ms-letter-spacing:0.03em;letter-spacing:0.03em;text-transform:uppercase;color:#333;}.css-5gimkt:after{content:’Collapse’;}.css-rdoyk0{-webkit-transition:all 0.5s ease;transition:all 0.5s ease;-webkit-transform:rotate(180deg);-ms-transform:rotate(180deg);transform:rotate(180deg);}.css-eb027h{max-height:5000px;-webkit-transition:max-height 0.5s ease;transition:max-height 0.5s ease;}.css-6mllg9{-webkit-transition:all 0.5s ease;transition:all 0.5s ease;position:relative;opacity:0;}.css-6mllg9:before{content:”;background-image:linear-gradient(180deg,transparent,#ffffff);background-image:-webkit-linear-gradient(270deg,rgba(255,255,255,0),#ffffff);height:80px;width:100%;position:absolute;bottom:0px;pointer-events:none;}.css-uf1ume{display:-webkit-box;display:-webkit-flex;display:-ms-flexbox;display:flex;-webkit-box-pack:justify;-webkit-justify-content:space-between;-ms-flex-pack:justify;justify-content:space-between;}.css-wxi1cx{display:-webkit-box;display:-webkit-flex;display:-ms-flexbox;display:flex;-webkit-flex-direction:column;-ms-flex-direction:column;flex-direction:column;-webkit-align-self:flex-end;-ms-flex-item-align:end;align-self:flex-end;}.css-12vbvwq{background-color:white;border:1px solid #e2e2e2;width:calc(100% – 40px);max-width:600px;margin:1.5rem auto 1.9rem;padding:15px;box-sizing:border-box;}@media (min-width:740px){.css-12vbvwq{padding:20px;width:100%;}}.css-12vbvwq:focus{outline:1px solid #e2e2e2;}#NYT_BELOW_MAIN_CONTENT_REGION .css-12vbvwq{border:none;padding:10px 0 0;border-top:2px solid #121212;}.css-12vbvwq[data-truncated] .css-rdoyk0{-webkit-transform:rotate(0deg);-ms-transform:rotate(0deg);transform:rotate(0deg);}.css-12vbvwq[data-truncated] .css-eb027h{max-height:300px;overflow:hidden;-webkit-transition:none;transition:none;}.css-12vbvwq[data-truncated] .css-5gimkt:after{content:’See more’;}.css-12vbvwq[data-truncated] .css-6mllg9{opacity:1;}.css-qjk116{margin:0 auto;overflow:hidden;}.css-qjk116 strong{font-weight:700;}.css-qjk116 em{font-style:italic;}.css-qjk116 a{color:#326891;-webkit-text-decoration:underline;text-decoration:underline;text-underline-offset:1px;-webkit-text-decoration-thickness:1px;text-decoration-thickness:1px;-webkit-text-decoration-color:#326891;text-decoration-color:#326891;}.css-qjk116 a:visited{color:#326891;-webkit-text-decoration-color:#326891;text-decoration-color:#326891;}.css-qjk116 a:hover{-webkit-text-decoration:none;text-decoration:none;}Still, other experts said that the corpus of evidence pointed to a disparity that would be worth exploring, at least in people who respond weakly to vaccines, including older adults and immunocompromised people.“At the end of the day, I do think there are subtle but real differences between Moderna and Pfizer,” Dr. Jeffrey Wilson, an immunologist and physician at the University of Virginia in Charlottesville who was a co-author of one such study, published in the journal JAMA this month. “In high-risk populations, it might be relevant. It’d be good if people took a close look.”“Pfizer is a big hammer,” Dr. Wilson added, but “Moderna is a sledgehammer.”Several factors might underlie the divergence. The vaccines differ in their dosing and in the time between the first and second doses.Vaccine manufacturers would typically have enough time to test a range of doses before choosing one — and they have done such testing for their trials of the coronavirus vaccine in children.But in the midst of a pandemic last year, the companies had to guess at the optimal dose. Pfizer went with 30 micrograms, Moderna with 100.Moderna’s vaccine relies on a liquid nanoparticle, which can deliver the larger dose. And the first and second shots of that vaccine are staggered by four weeks, compared with three for the Pfizer-BioNTech vaccine.The extra week may give immune cells more time to proliferate before the second dose, said Dr. Paul Burton, Moderna’s chief medical officer. “We need to keep studying this and to do more research, but I think it’s plausible.”Moderna’s team recently showed that a half dose of the vaccine still sent antibody levels soaring. Based on those data, the company asked the F.D.A. this month to authorize 50 micrograms, the half dose, as a booster shot.There is limited evidence showing the effect of that dose, and none on how long the higher antibody levels might last. Federal regulators are reviewing Moderna’s data to determine whether the available data are sufficient to authorize a booster shot of the half dose.Ultimately, both vaccines are still holding steady against severe illness and hospitalization, especially in people under 65, Dr. Moore said.Scientists had initially hoped that the vaccines would have an efficacy of 50 or 60 percent. “We would have all seen that as great result and been happy with it,” he said. “Fast forward to now, and we’re debating whether 96.3 percent vaccine efficacy for Moderna versus 88.8 percent for Pfizer is a big deal.”

Scientific advisers to the Centers for Disease Control and Prevention are scheduled to meet on Wednesday to decide which Americans should get booster shots of the Pfizer-BioNTech coronavirus vaccine — and when.The committee’s discussions are normally a scientific affair of little interest to most people. But this meeting is likely to be closely watched — the stakes are high. It follows a dramatic exchange at the Food and Drug Administration on Friday, when advisers overwhelmingly rejected a proposal to offer Pfizer booster shots for Americans over 16, but then voted unanimously in favor of third doses for some high-risk people and those older than 65.The role of the C.D.C. advisers on Wednesday is to decide who belongs in those high-risk groups. Depending on their verdict, booster shots could be offered to most Americans — or only to a select few.The decision may come as late as Thursday. But it is likely to be too late for the Biden administration, which had planned to begin offering third doses this week to most fully vaccinated adults in the United States.At the meeting on Friday, senior scientists at Pfizer and the Israeli Ministry of Health presented data they said indicated waning immunity in people who received the Pfizer vaccine months earlier. Boosting immune defenses with a third shot has made a difference in Israel, they said, and could stem the tide of infections in the United States.The F.D.A. advisers also evaluated data from the C.D.C. on the trajectory of the virus in the United States, as well as summaries from several studies on the effectiveness of the vaccines.But after reviewing the evidence, the scientists on the committee concluded that while protection against infection may be waning, especially in older adults, the original two-shot regimen still offers excellent protection against severe illness and hospitalization in most people.“It’s unclear that everyone needs to be boosted, other than a subset of the population that clearly would be at high risk for serious disease,” said Dr. Michael G. Kurilla, a committee member and official at the National Institutes of Health.One key difference between Israel and the United States may explain why the two countries have had different experiences with the vaccine: The countries define severe illness differently.In Israel, anyone with an accelerated respiratory rate and an oxygen level of below 94 percent is severely ill. By contrast, the C.D.C. reserves that category for people who are sick enough to be hospitalized, said Dr. Sara Oliver, a C.D.C. scientist who presented the American data..css-1xzcza9{list-style-type:disc;padding-inline-start:1em;}.css-3btd0c{font-family:nyt-franklin,helvetica,arial,sans-serif;font-size:1rem;line-height:1.375rem;color:#333;margin-bottom:0.78125rem;}@media (min-width:740px){.css-3btd0c{font-size:1.0625rem;line-height:1.5rem;margin-bottom:0.9375rem;}}.css-3btd0c strong{font-weight:600;}.css-3btd0c em{font-style:italic;}.css-w739ur{margin:0 auto 5px;font-family:nyt-franklin,helvetica,arial,sans-serif;font-weight:700;font-size:1.125rem;line-height:1.3125rem;color:#121212;}#NYT_BELOW_MAIN_CONTENT_REGION .css-w739ur{font-family:nyt-cheltenham,georgia,’times new roman’,times,serif;font-weight:700;font-size:1.375rem;line-height:1.625rem;}@media (min-width:740px){#NYT_BELOW_MAIN_CONTENT_REGION .css-w739ur{font-size:1.6875rem;line-height:1.875rem;}}@media (min-width:740px){.css-w739ur{font-size:1.25rem;line-height:1.4375rem;}}.css-9s9ecg{margin-bottom:15px;}.css-16ed7iq{width:100%;display:-webkit-box;display:-webkit-flex;display:-ms-flexbox;display:flex;-webkit-align-items:center;-webkit-box-align:center;-ms-flex-align:center;align-items:center;-webkit-box-pack:center;-webkit-justify-content:center;-ms-flex-pack:center;justify-content:center;padding:10px 0;background-color:white;}.css-pmm6ed{display:-webkit-box;display:-webkit-flex;display:-ms-flexbox;display:flex;-webkit-align-items:center;-webkit-box-align:center;-ms-flex-align:center;align-items:center;}.css-pmm6ed > :not(:first-child){margin-left:5px;}.css-5gimkt{font-family:nyt-franklin,helvetica,arial,sans-serif;font-size:0.8125rem;font-weight:700;-webkit-letter-spacing:0.03em;-moz-letter-spacing:0.03em;-ms-letter-spacing:0.03em;letter-spacing:0.03em;text-transform:uppercase;color:#333;}.css-5gimkt:after{content:’Collapse’;}.css-rdoyk0{-webkit-transition:all 0.5s ease;transition:all 0.5s ease;-webkit-transform:rotate(180deg);-ms-transform:rotate(180deg);transform:rotate(180deg);}.css-eb027h{max-height:5000px;-webkit-transition:max-height 0.5s ease;transition:max-height 0.5s ease;}.css-6mllg9{-webkit-transition:all 0.5s ease;transition:all 0.5s ease;position:relative;opacity:0;}.css-6mllg9:before{content:”;background-image:linear-gradient(180deg,transparent,#ffffff);background-image:-webkit-linear-gradient(270deg,rgba(255,255,255,0),#ffffff);height:80px;width:100%;position:absolute;bottom:0px;pointer-events:none;}.css-uf1ume{display:-webkit-box;display:-webkit-flex;display:-ms-flexbox;display:flex;-webkit-box-pack:justify;-webkit-justify-content:space-between;-ms-flex-pack:justify;justify-content:space-between;}.css-wxi1cx{display:-webkit-box;display:-webkit-flex;display:-ms-flexbox;display:flex;-webkit-flex-direction:column;-ms-flex-direction:column;flex-direction:column;-webkit-align-self:flex-end;-ms-flex-item-align:end;align-self:flex-end;}.css-12vbvwq{background-color:white;border:1px solid #e2e2e2;width:calc(100% – 40px);max-width:600px;margin:1.5rem auto 1.9rem;padding:15px;box-sizing:border-box;}@media (min-width:740px){.css-12vbvwq{padding:20px;width:100%;}}.css-12vbvwq:focus{outline:1px solid #e2e2e2;}#NYT_BELOW_MAIN_CONTENT_REGION .css-12vbvwq{border:none;padding:10px 0 0;border-top:2px solid #121212;}.css-12vbvwq[data-truncated] .css-rdoyk0{-webkit-transform:rotate(0deg);-ms-transform:rotate(0deg);transform:rotate(0deg);}.css-12vbvwq[data-truncated] .css-eb027h{max-height:300px;overflow:hidden;-webkit-transition:none;transition:none;}.css-12vbvwq[data-truncated] .css-5gimkt:after{content:’See more’;}.css-12vbvwq[data-truncated] .css-6mllg9{opacity:1;}.css-qjk116{margin:0 auto;overflow:hidden;}.css-qjk116 strong{font-weight:700;}.css-qjk116 em{font-style:italic;}.css-qjk116 a{color:#326891;-webkit-text-decoration:underline;text-decoration:underline;text-underline-offset:1px;-webkit-text-decoration-thickness:1px;text-decoration-thickness:1px;-webkit-text-decoration-color:#326891;text-decoration-color:#326891;}.css-qjk116 a:visited{color:#326891;-webkit-text-decoration-color:#326891;text-decoration-color:#326891;}.css-qjk116 a:hover{-webkit-text-decoration:none;text-decoration:none;}Some committee experts said they also did not feel comfortable offering booster shots to young people who may not need them, when the risks of a third dose are unknown.The vaccines have been tied to rare cases of myocarditis, inflammation of the heart, in younger people. The risk is very small, and studies have shown that Covid-19 is much more likely to cause the condition.Last week brought other research in support of the F.D.A. committee’s decision, including one paper by an international team of scientists that analyzed dozens of studies and concluded that the world would be better served by using vaccine doses to protect the billions who remain unvaccinated.The authors of that study included the top two vaccine experts at the F.D.A., who announced plans to leave the agency this fall. Their departure is in part in protest of the Biden administration’s push for boosters before federal scientists and regulators had reviewed the evidence.

Dr. Nkengasong will be the first person of African origin to oversee the U.S. government program combating H.I.V., which has ravaged the continent.The Biden administration plans to nominate John Nkengasong, a virologist and director of the Africa Centers for Disease Control and Prevention, to lead the President’s Emergency Plan for AIDS Relief, according to several sources familiar with the matter.President Biden is expected to make the announcement in the coming days.PEPFAR is a $7 billion operation that funds and sets goals for AIDS care in many nations, most of them in Africa. Dr. Nkengasong, who was born in Cameroon, is the first person of African origin to head the program, which is housed in the Department of State.“This is a huge leap forward for the U.S. government to name someone from the region where much of the PEPFAR work is,” said Mitchell Warren, executive director of AVAC, a nonprofit organization promoting H.I.V. treatment worldwide. “It shows a commitment to truly listening to and learning from the people PEPFAR is meant to serve.”Dr. Nkengasong could not immediately be reached for comment.The AIDS program was last led by Dr. Deborah Birx, who left in February 2020 to join the White House coronavirus task force. The Biden administration has come under severe criticism for leaving the program leaderless, especially at a time when the pandemic is setting back years of progress against H.I.V.In July, more than 50 advocacy organizations sent a letter to Mr. Biden calling the delay “unacceptable.”Compared with 2019, the number of people in 2020 who sought testing for H.I.V. decreased by 22 percent, and the number who opted for H.I.V. prevention services fell by 12 percent, according to a report published earlier this month.“Deep inequities in access to science, justice and human rights are fueling the H.I.V. pandemic,” said Maureen Milanga, a director of policy at the advocacy group Health GAP in Nairobi, Kenya. Dr. Nkengasong “must put the U.S. global AIDS response back on the front burner.”Dr. Nkengasong has been the director of the Africa C.D.C. since 2016, when the organization was established. He has decades of experience in global health, with long stints at the World Health Organization and the U.S. Centers for Disease Control and Prevention. The W.H.O. appointed him as its special envoy for Africa during the Covid-19 pandemic.Several public health experts and activists called Dr. Nkengasong an unexpected but inspired choice.“He’s a very strong public health leader with many years of experience, and would bring great connectivity to African leaders and community partners,” said Dr. Chris Beyrer, a professor of public health and human rights at the Johns Hopkins Bloomberg School of Public Health. (Dr. Beyrer was on a short list of candidates for the position.)PEPFAR, the largest public health program in the United States, was started in 2003 by President George W. Bush. Since its launch, the U.S. government has invested more than $85 billion in more than 50 countries, saving an estimated 20 million lives.Funds distributed by the scheme are used to support prevention programs, testing and antiretroviral therapy for H.I.V. Some directors have been heavy-handed in setting priorities for African nations, so a leader like Dr. Nkengasong who knows and is trusted by Africans is a welcome change, experts said.“To have somebody who’s a known figure both in the U.S. and around the world, and in Africa, is a sign that they’re taking this seriously — that they understand that raising up African leadership is really important,” said Gregg Gonsalves, a longtime H.I.V. activist and an epidemiologist at the Yale School of Public Health.Cameroon, Dr. Nkengasong’s country of birth, has a high prevalence of H.I.V. and tuberculosis. And he has been vocal in his support of training local scientists and doctors to lead public health and research in the continent. In 2011, he helped establish the African Society for Laboratory Medicine.Dr. Nkengasong was knighted in November 2018 by the government of Cameroon for his contributions to public health. He serves as an adviser to the Coalition for Epidemic Preparedness Innovations and the International AIDS Vaccine Initiative, among others. For his leadership in the Covid-19 pandemic, he was included in Time magazine’s 2021 list of the 100 most influential people.The only downside to Dr. Nkengasong leading PEPFAR is that he is also needed to combat other infectious disease efforts in Africa, Mr. Gonsalves said: “It’s a loss for Africa C.D.C.”

Vaccinated kids aged 5 to 11 showed evidence of protection against the virus, the company said. The data must be reviewed by the F.D.A. before children can be inoculated.The Pfizer-BioNTech coronavirus vaccine has been shown to be safe and highly effective in young children aged 5 to 11 years, the companies announced early Monday morning. The news should help ease months of anxiety among parents and teachers about when children, and their close contacts, might be shielded from the coronavirus.The need is urgent: Children now account for more than one in five new cases, and the highly contagious Delta variant has sent more children into hospitals and intensive care units in the past few weeks than at any other time in the pandemic.Pfizer and BioNTech plan to apply to the Food and Drug Administration by the end of the month for authorization to use the vaccine in these children. If the regulatory review goes as smoothly as it did for older children and adults, millions of elementary school students could be inoculated before Halloween.Trial results for children younger than 5 are not expected till the fourth quarter of this year at the earliest, according to Dr. Bill Gruber, a senior vice president at Pfizer and a pediatrician.Pfizer and BioNTech announced the results in a statement that did not include detailed data from the trial. The findings have not yet been peer-reviewed nor published in a scientific journal.But the new results dovetail with those seen in older children and in adults, experts said.“There’s going to be a huge number of parents who are going to heave a big sigh of relief when they hear this,” said Dr. Kristin Oliver, a pediatrician and vaccine expert at Mount Sinai Hospital in New York. “We’ve been waiting for these kids to be protected.”Children have a much lower risk of Covid-19 than adults, even when exposed to the Delta variant. Still, some small number of infected children develop a life-threatening condition called multi-system inflammatory syndrome in children, or MIS-C. Still others may have lingering symptoms for months.Nearly 30,000 children were hospitalized for Covid in August; the least vaccinated states reported the highest rates. At Seattle Children’s hospital, about half of the children who are admitted for Covid are older than 12, according to Dr. Danielle Zerr, a pediatric infectious diseases expert at the hospital.“I’ve been dismayed at the fact that the sickest children in our hospital with acute Covid-19 or MIS-C are children who could have been vaccinated,” Dr. Zerr said.A 2-month-old on a ventilator for respiratory failure because of Covid-19 at Children’s Hospital New Orleans.Erin Schaff/The New York TimesAs ideological battles over masking and vaccine mandates play out in communities, the reopening of schools has fueled the surge. In Mississippi, among the states without a mask mandate, nearly 6,000 students tested positive for the virus in one week, and more than 30,000 students, teachers and staff had to be quarantined.One county in South Carolina — where mask mandates are banned — had to quarantine more than 2,000 students in one day. Remote learning is not an option in many districts, so the safety of some medically vulnerable children in many parts of the country has become subject to the actions of others.Unvaccinated children, even if they do not become ill themselves, can spread the virus to family members, teachers and others they interact with regularly — among them grandparents or those who are vulnerable to severe disease or death.Mask wearing and good air circulation can significantly cut down virus transmission. But children are as likely as adults to transmit the virus to others, and more likely to do so than adults older than 60, according to a recent review of the evidence by the Centers for Disease Control and Prevention.Pfizer’s trial included 2,268 children ages 5 to 11, two-thirds of whom received two doses of the vaccine three weeks apart; the rest were injected with two doses of saltwater placebo.Given how rarely children become severely ill, the trial was not big enough to draw meaningful conclusions about the vaccine’s ability to prevent Covid or hospitalization. Instead, the researchers relied on measurements of the youngsters’ immune response, on the assumption that the protective levels of antibodies seen in older people would be as protective in younger children.The children who got the vaccine produced a strong immune response, comparable to the levels of antibodies seen in the earlier trials of participants aged 16 to 25 years. But children in the 5- to 11-year-old group achieved this response with 10 micrograms of the vaccine, a third of the dose given to older children and adults.At higher doses, the researchers observed more side effects in younger children, including fever, headache and fatigue, although none were severe, Dr. Gruber said. With the 10-microgram dose, “we’re actually seeing after the second dose, less fever, less chills than we see in the 16- to 25-year-olds.”Immune defenses weaken with age, and the side effects also become milder. This decline in potency is the reason most vaccines are meted out in childhood — and why a much lower dose is often enough for children, said Dr. Yvonne Maldonado, who led the trial at Stanford University and chairs the American Academy of Pediatrics’ infectious disease committee.The first day of school at Normont Early Education Center in Los Angeles in August.Allison Zaucha for The New York Times“You want to hit the sweet spot, where you’re giving the lowest dose that might elicit reactions, but also high enough to get you a good, sustainable antibody response,” she said.In children younger than 5, just three micrograms — a tenth of the adult dose — is being tested in trials and seems likely to prove sufficient, she said..css-1xzcza9{list-style-type:disc;padding-inline-start:1em;}.css-3btd0c{font-family:nyt-franklin,helvetica,arial,sans-serif;font-size:1rem;line-height:1.375rem;color:#333;margin-bottom:0.78125rem;}@media (min-width:740px){.css-3btd0c{font-size:1.0625rem;line-height:1.5rem;margin-bottom:0.9375rem;}}.css-3btd0c strong{font-weight:600;}.css-3btd0c em{font-style:italic;}.css-w739ur{margin:0 auto 5px;font-family:nyt-franklin,helvetica,arial,sans-serif;font-weight:700;font-size:1.125rem;line-height:1.3125rem;color:#121212;}#NYT_BELOW_MAIN_CONTENT_REGION .css-w739ur{font-family:nyt-cheltenham,georgia,’times new roman’,times,serif;font-weight:700;font-size:1.375rem;line-height:1.625rem;}@media (min-width:740px){#NYT_BELOW_MAIN_CONTENT_REGION .css-w739ur{font-size:1.6875rem;line-height:1.875rem;}}@media (min-width:740px){.css-w739ur{font-size:1.25rem;line-height:1.4375rem;}}.css-9s9ecg{margin-bottom:15px;}.css-16ed7iq{width:100%;display:-webkit-box;display:-webkit-flex;display:-ms-flexbox;display:flex;-webkit-align-items:center;-webkit-box-align:center;-ms-flex-align:center;align-items:center;-webkit-box-pack:center;-webkit-justify-content:center;-ms-flex-pack:center;justify-content:center;padding:10px 0;background-color:white;}.css-pmm6ed{display:-webkit-box;display:-webkit-flex;display:-ms-flexbox;display:flex;-webkit-align-items:center;-webkit-box-align:center;-ms-flex-align:center;align-items:center;}.css-pmm6ed > :not(:first-child){margin-left:5px;}.css-5gimkt{font-family:nyt-franklin,helvetica,arial,sans-serif;font-size:0.8125rem;font-weight:700;-webkit-letter-spacing:0.03em;-moz-letter-spacing:0.03em;-ms-letter-spacing:0.03em;letter-spacing:0.03em;text-transform:uppercase;color:#333;}.css-5gimkt:after{content:’Collapse’;}.css-rdoyk0{-webkit-transition:all 0.5s ease;transition:all 0.5s ease;-webkit-transform:rotate(180deg);-ms-transform:rotate(180deg);transform:rotate(180deg);}.css-eb027h{max-height:5000px;-webkit-transition:max-height 0.5s ease;transition:max-height 0.5s ease;}.css-6mllg9{-webkit-transition:all 0.5s ease;transition:all 0.5s ease;position:relative;opacity:0;}.css-6mllg9:before{content:”;background-image:linear-gradient(180deg,transparent,#ffffff);background-image:-webkit-linear-gradient(270deg,rgba(255,255,255,0),#ffffff);height:80px;width:100%;position:absolute;bottom:0px;pointer-events:none;}.css-uf1ume{display:-webkit-box;display:-webkit-flex;display:-ms-flexbox;display:flex;-webkit-box-pack:justify;-webkit-justify-content:space-between;-ms-flex-pack:justify;justify-content:space-between;}.css-wxi1cx{display:-webkit-box;display:-webkit-flex;display:-ms-flexbox;display:flex;-webkit-flex-direction:column;-ms-flex-direction:column;flex-direction:column;-webkit-align-self:flex-end;-ms-flex-item-align:end;align-self:flex-end;}.css-12vbvwq{background-color:white;border:1px solid #e2e2e2;width:calc(100% – 40px);max-width:600px;margin:1.5rem auto 1.9rem;padding:15px;box-sizing:border-box;}@media (min-width:740px){.css-12vbvwq{padding:20px;width:100%;}}.css-12vbvwq:focus{outline:1px solid #e2e2e2;}#NYT_BELOW_MAIN_CONTENT_REGION .css-12vbvwq{border:none;padding:10px 0 0;border-top:2px solid #121212;}.css-12vbvwq[data-truncated] .css-rdoyk0{-webkit-transform:rotate(0deg);-ms-transform:rotate(0deg);transform:rotate(0deg);}.css-12vbvwq[data-truncated] .css-eb027h{max-height:300px;overflow:hidden;-webkit-transition:none;transition:none;}.css-12vbvwq[data-truncated] .css-5gimkt:after{content:’See more’;}.css-12vbvwq[data-truncated] .css-6mllg9{opacity:1;}.css-qjk116{margin:0 auto;overflow:hidden;}.css-qjk116 strong{font-weight:700;}.css-qjk116 em{font-style:italic;}.css-qjk116 a{color:#326891;-webkit-text-decoration:underline;text-decoration:underline;text-underline-offset:1px;-webkit-text-decoration-thickness:1px;text-decoration-thickness:1px;-webkit-text-decoration-color:#326891;text-decoration-color:#326891;}.css-qjk116 a:visited{color:#326891;-webkit-text-decoration-color:#326891;text-decoration-color:#326891;}.css-qjk116 a:hover{-webkit-text-decoration:none;text-decoration:none;}The F.D.A.’s full approval of the Pfizer-BioNTech vaccine in August did not include children aged 12 to 15, who are still getting the vaccine under emergency use authorization. As they did for adolescents, the companies will seek an emergency authorization for children aged 5 to 11.Scientists at the F.D.A. must then weigh the benefits of the vaccine against the risk of side effects. In rare cases, the vaccine has led to myocarditis, an inflammation of the heart, in young people.But a large Israeli study, based on electronic health records of two million people aged 16 and older, found that Covid is far more likely to cause these heart problems.In order to detect side effects in younger children, the F.D.A. in July asked Pfizer-BioNtech and Moderna to expand their trials to include 3,000 children. But based on the company’s conversations with the F.D.A., Dr. Gruber said he believed the agency would greenlight the vaccine with the data available so far.Discussions about the vaccine’s risks for children aged 6 months to 5 years are likely to be even more fraught than the vehement disagreements over immunizing healthy adults or teenagers.“There’s some people out there who don’t really feel that there’s convincing data that under-fives need to be vaccinated,” Dr. Maldonado said.Even though most children are spared severe illness following infection, pediatric hospitals and I.C.U. units are overflowing, she added: “Why wouldn’t you want to prevent an infection that could potentially put your child in the I.C.U.?”

Advisers to the Food and Drug Administration on Friday must confront a range of bewildering scientific questions before deciding whether to authorize coronavirus vaccine booster shots — and if so, for whom.Three important pieces of research landed just this week. On Monday, in the journal The Lancet, an international team of scientists analyzed dozens of studies and concluded that boosters are not yet needed by the general population, and that the world would be better served by using vaccine doses to protect the billions of people who remain unvaccinated.Two of the authors are vaccine experts at the F.D.A. itself, and both had already announced plans to resign over what they felt was undue pressure from the Biden administration to approve booster shots.On Wednesday, scientists at the agency posted an assessment online hinting that they, too, are unconvinced that there’s enough evidence that boosters are needed. “Overall, data indicate that currently U.S.-licensed or authorized Covid-19 vaccines still afford protection against severe Covid-19 disease and death in the United States,” according to their executive summary.White House officials have said they are particularly worried by data from Israel, where officials have said that vaccinated people are seeing waning immune responses and higher rates of infection. Alarmed by the rise in cases, Israeli officials offered third doses of the vaccine to everyone older than 12.Researchers from Israel published early results from that rollout on Wednesday in the New England Journal of Medicine — but few outside scientists found the findings convincing.The team collected data on the effects of booster shots from the health records of more than 1.1 million people over age 60. At least 12 days after the booster, rates of infection were elevenfold lower — and rates of severe disease nearly twentyfold lower — in those who received a booster compared with those who had received only two doses, the researchers found.The results are unsurprising, experts said, and do not indicate long-term benefit.Dr. Celine Gounder, an infectious disease expert at Bellevue Hospital in New York and a former member of the Biden-Harris Covid-19 advisory council.Amr Alfiky/The New York Times“We have known for some time that the vaccines elicit less robust immune responses in the elderly,” said Dr. Celine Gounder, an infectious disease specialist at Bellevue Hospital Center and a former adviser to the Biden administration. “Recommending additional doses of vaccine for the elderly isn’t controversial.”Vaccination remains powerfully protective against severe illness and hospitalization in the vast majority of people in all of the studies published so far, experts said. But the vaccines do seem less potent against infections in people of all ages, particularly those exposed to the highly contagious Delta variant.The cumulative data so far suggest that only older adults will need boosters — and maybe not even them. But White House officials have said that they do not want to wait for hospitalizations to begin rising — if they ever do — among the vaccinated before taking action..css-1xzcza9{list-style-type:disc;padding-inline-start:1em;}.css-3btd0c{font-family:nyt-franklin,helvetica,arial,sans-serif;font-size:1rem;line-height:1.375rem;color:#333;margin-bottom:0.78125rem;}@media (min-width:740px){.css-3btd0c{font-size:1.0625rem;line-height:1.5rem;margin-bottom:0.9375rem;}}.css-3btd0c strong{font-weight:600;}.css-3btd0c em{font-style:italic;}.css-w739ur{margin:0 auto 5px;font-family:nyt-franklin,helvetica,arial,sans-serif;font-weight:700;font-size:1.125rem;line-height:1.3125rem;color:#121212;}#NYT_BELOW_MAIN_CONTENT_REGION .css-w739ur{font-family:nyt-cheltenham,georgia,’times new roman’,times,serif;font-weight:700;font-size:1.375rem;line-height:1.625rem;}@media (min-width:740px){#NYT_BELOW_MAIN_CONTENT_REGION .css-w739ur{font-size:1.6875rem;line-height:1.875rem;}}@media (min-width:740px){.css-w739ur{font-size:1.25rem;line-height:1.4375rem;}}.css-9s9ecg{margin-bottom:15px;}.css-16ed7iq{width:100%;display:-webkit-box;display:-webkit-flex;display:-ms-flexbox;display:flex;-webkit-align-items:center;-webkit-box-align:center;-ms-flex-align:center;align-items:center;-webkit-box-pack:center;-webkit-justify-content:center;-ms-flex-pack:center;justify-content:center;padding:10px 0;background-color:white;}.css-pmm6ed{display:-webkit-box;display:-webkit-flex;display:-ms-flexbox;display:flex;-webkit-align-items:center;-webkit-box-align:center;-ms-flex-align:center;align-items:center;}.css-pmm6ed > :not(:first-child){margin-left:5px;}.css-5gimkt{font-family:nyt-franklin,helvetica,arial,sans-serif;font-size:0.8125rem;font-weight:700;-webkit-letter-spacing:0.03em;-moz-letter-spacing:0.03em;-ms-letter-spacing:0.03em;letter-spacing:0.03em;text-transform:uppercase;color:#333;}.css-5gimkt:after{content:’Collapse’;}.css-rdoyk0{-webkit-transition:all 0.5s ease;transition:all 0.5s ease;-webkit-transform:rotate(180deg);-ms-transform:rotate(180deg);transform:rotate(180deg);}.css-eb027h{max-height:5000px;-webkit-transition:max-height 0.5s ease;transition:max-height 0.5s ease;}.css-6mllg9{-webkit-transition:all 0.5s ease;transition:all 0.5s ease;position:relative;opacity:0;}.css-6mllg9:before{content:”;background-image:linear-gradient(180deg,transparent,#ffffff);background-image:-webkit-linear-gradient(270deg,rgba(255,255,255,0),#ffffff);height:80px;width:100%;position:absolute;bottom:0px;pointer-events:none;}.css-uf1ume{display:-webkit-box;display:-webkit-flex;display:-ms-flexbox;display:flex;-webkit-box-pack:justify;-webkit-justify-content:space-between;-ms-flex-pack:justify;justify-content:space-between;}.css-wxi1cx{display:-webkit-box;display:-webkit-flex;display:-ms-flexbox;display:flex;-webkit-flex-direction:column;-ms-flex-direction:column;flex-direction:column;-webkit-align-self:flex-end;-ms-flex-item-align:end;align-self:flex-end;}.css-12vbvwq{background-color:white;border:1px solid #e2e2e2;width:calc(100% – 40px);max-width:600px;margin:1.5rem auto 1.9rem;padding:15px;box-sizing:border-box;}@media (min-width:740px){.css-12vbvwq{padding:20px;width:100%;}}.css-12vbvwq:focus{outline:1px solid #e2e2e2;}#NYT_BELOW_MAIN_CONTENT_REGION .css-12vbvwq{border:none;padding:10px 0 0;border-top:2px solid #121212;}.css-12vbvwq[data-truncated] .css-rdoyk0{-webkit-transform:rotate(0deg);-ms-transform:rotate(0deg);transform:rotate(0deg);}.css-12vbvwq[data-truncated] .css-eb027h{max-height:300px;overflow:hidden;-webkit-transition:none;transition:none;}.css-12vbvwq[data-truncated] .css-5gimkt:after{content:’See more’;}.css-12vbvwq[data-truncated] .css-6mllg9{opacity:1;}.css-qjk116{margin:0 auto;overflow:hidden;}.css-qjk116 strong{font-weight:700;}.css-qjk116 em{font-style:italic;}.css-qjk116 a{color:#326891;-webkit-text-decoration:underline;text-decoration:underline;text-underline-offset:1px;-webkit-text-decoration-thickness:1px;text-decoration-thickness:1px;-webkit-text-decoration-color:#326891;text-decoration-color:#326891;}.css-qjk116 a:visited{color:#326891;-webkit-text-decoration-color:#326891;text-decoration-color:#326891;}.css-qjk116 a:hover{-webkit-text-decoration:none;text-decoration:none;}The Biden administration has said that booster doses could be rolled out quickly, should the F.D.A. and the Centers for Disease Control and Prevention deem them necessary. An advisory committee to the C.D.C. is scheduled to meet next week to take up the question.British scientists have recommended giving third doses to adults over 50 and other medically vulnerable people. France, Germany, Denmark and Spain are also considering boosters for older adults or have already begun administering them. Israel is already contemplating fourth doses for its population.But recent history leaves many experts leery of adding the United States to the list.Dr. Luciana Borio, a former acting chief scientist at the F.D.A., criticized the Biden administration for announcing a plan for boosters before federal scientists could review the evidence.The Trump administration pressured scientists at the F.D.A. to authorize hydroxychroloquine and convalescent plasma, for example, without enough evidence to support either treatment. “It seems to me that there’s been a process foul in how we go about making those decisions,” Dr. Borio said.“We need an F.D.A. that has people making these decisions and retaining that ability to make those decisions independently and based on science alone. If this changes, we all lose.”

None of the data on coronavirus vaccines so far provides credible evidence in support of boosters for the general population, according to a review published on Monday by an international group of scientists, including some at the Food and Drug Administration and the World Health Organization.The Biden administration has proposed administering vaccine boosters eight months after the initial shots. But many scientists have opposed the plan, saying the vaccines continue to be powerfully protective against severe illness and hospitalization. A committee of advisers to the F.D.A. is scheduled to meet on Friday to review the data.In the new review, published in The Lancet, experts said that whatever advantage boosters provide would not outweigh the benefit of using those doses to protect the billions of people who remain unvaccinated worldwide. Boosters may be useful in some people with weak immune systems, they said, but are not yet needed for the general population.The 18 authors include Philip Krause and Marion Gruber, F.D.A. scientists who resigned from the agency, at least in part because they disagreed with the Biden administration’s push for boosters before federal scientists could review the evidence and make recommendations.Several studies published by the Centers for Disease Control and Prevention, including three on Friday, suggest that while efficacy against infection with the Delta variant seems to wane slightly over time, the vaccines hold steady against severe illness in all age groups. Only in older adults over 75 do the vaccines show some weakening in protection against hospitalization.Immunity conferred by vaccines relies on protection both from antibodies and from immune cells. Although the levels of antibodies may wane over time — and raise the risk of infection — the body’s memory of the virus is long-lived.The vaccines are slightly less effective against infection with the Delta variant than with the Alpha variant, but the virus has not yet evolved to evade the sustained responses from immune cells, the experts said. Boosters may eventually be needed even for the general population if a variant emerges that sidesteps the immune response.The experts cautioned that promoting boosters before they are needed, as well as any reports of side effects from booster shots such as heart problems or Guillain-Barre syndrome, may undermine confidence in the primary vaccination.Data from Israel suggest that booster doses enhance protection against infection. But that evidence was collected just a week or so after the third dose and may not hold up over time, the experts said.

After the Taliban’s takeover, international donors withdrew funds that hospitals and clinics depended on. Now a fourth wave of Covid looms.The health care system in Afghanistan is teetering on the edge of collapse, endangering the lives of millions and compounding a deepening humanitarian crisis, public health experts warn.The country’s health care has been propped up by aid from international donors. But after the Taliban seized power, the World Bank and other organizations froze $600 million in health care aid. The Biden administration, too, is struggling with how to dispense donor money to a country now being run by several senior Taliban leaders whom the United States has designated to be terrorists.If World Bank funding is not restored quickly, an exodus of health care workers may result. Many have remained on the job despite significant personal risks; already some have not been paid for months. Along with the loss of supplies, the cutoff would effectively end health care services in 31 of the nation’s 34 provinces, humanitarian groups say.Afghanistan is already on the brink of universal poverty, according to a United Nations report on Thursday, and only its richest citizens will be able to afford health care. Assuming that health care coverage is cut by half because of the funding loss, deaths among women and children will increase by at least 33 percent over the next year — nearly 2,000 women and more than 26,000 children per year — according to one analysis.“There have been massive improvements in many metrics of health, like maternal mortality, tuberculosis and malaria,” said Peter Sands, executive director of the Global Fund, an advocacy group that funds campaigns against H.I.V., malaria and tuberculosis.“There’s a real question as to how those are sustained, and what a tragedy it would be if that was reversed.”In recent years, Afghanistan had made big strides in reducing maternal and child deaths by more than 50 percent, and increasing life expectancy for men and women by 10 years. Even so, most Afghans have had access to only rudimentary health care. The loss of humanitarian aid, and the looming fourth wave of the coronavirus, could devastate the nation.“We are losing personnel, we are losing lives, and the morale and momentum we had,” said Dr. Wahid Majrooh, who was health minister under the previous government and has stayed on. “The crisis is very, very extensive.”Afghanistan emerged from a third wave of virus infections just a few weeks ago, but it is already seeing a small uptick in cases, this time of the highly contagious Delta variant. Only 5 percent of the population have received at least one dose of a Covid-19 vaccine.“It’s terrible timing that this would happen, when right now we’re faced with a situation where humanitarian needs are escalating,” said Dr. Richard Brennan, the regional emergency director for the World Health Organization’s Eastern Mediterranean region.Cesarean sections, immunizations for polio, tuberculosis, tetanus and measles, diagnoses and treatment of TB, malaria, H.I.V., childhood nutrition, surgeries and routine health services, including family planning — all are at risk. The loss in aid is also constricting supply chains for medicines, oxygen and food for hospitals.Roughly two-thirds of the country’s health facilities are part of Sehatmandi, a three-year, $600 million project administered by the World Bank and funded by the U.S. Agency for International Development, the European Union, the World Bank and others. Because funds were put in effect through the Afghanistan Ministry of Public Health, the donors withdrew their support after the Taliban’s ouster of the previous administration.Dr. Majrooh, who studied global health policy at the London School of Hygiene & Tropical Medicine, said he appreciated the precarious situation of donor organizations but argued that the health of the population should supersede political considerations.Dr. Majrooh and humanitarian aid experts accused the funding organizations of abandoning Afghans when they most needed help.“I’m so surprised that at the time where they are the most needed, and where they can have the highest impact ever — it is at that time they have decided to pull out,” said Karl Blanchet, an expert in humanitarian studies at the University of Geneva who has worked closely with the Afghan health ministry.But others noted that the World Bank is hamstrung by limits set by its shareholders, and it had no choice but to withdraw financial support when similar upheavals unfolded in Yemen and Myanmar.“They have rules and regulations that don’t allow them to contribute funding to a government run by the Taliban,” Dr. Brennan said. “So they’ve got to find an alternate funding mechanism to channel those funds to ensure those health facilities continue to operate.”The shuttering of Sehatmandi clinics in Afghanistan is likely to overwhelm those funded by other means, aid workers said. In Herat, a hospital supported by Doctors Without Borders is among the few to remain open, according to Dr. Tankred Stoebe, the organization’s medical coordinator for the region.The 40-bed health care center is treating nearly three times as many children as usual, many of whom had to travel for hours for treatment, he said, and staff members have not had a day off in weeks. “We are totally stretched at the moment,” Dr. Stoebe said.One pediatric doctor at a Sehatmandi hospital has not been paid for three months, Dr. Stoebe said. The doctor already worked 250 hours a week, but had tacked on more hours at a private clinic to make ends meet.When no commercial flights were allowed into the country, medical supplies at many hospitals dwindled. Insurance costs for flights have skyrocketed, and funds don’t go as far. Trauma and emergency health kits, and testing kits for the coronavirus, are in particularly short supply.The Sehatmandi program contracts out the delivery of health services to more than 30 nongovernmental organizations. On Aug. 31, a week after the funding pause, an alliance of some of the NGOs warned that absent of immediate solutions, the organizations could not continue their work after Sept. 5.Without money for salaries or supplies, “we will be unable to offer our commitment for the continuation of services,” the organizations said in a letter to Dr. Majrooh. They urged the new regime to “take over all health facilities effective 10 September.”Dr. Majrooh said that he had communicated the urgency and scale of the crisis to Taliban leaders, but that no plan had yet materialized for assuming control of the country’s health care system.The NGOs also plan to appeal directly to the World Bank and other donors to resume support. But a sustainable solution may take time.In the short term, the W.H.O. plans to spend $66 million to keep 538 health care facilities afloat through the end of the year, Dr. Brennan said. In the meantime, representatives from the World Bank and global health organizations are working closely to come up with alternative funding mechanisms, according to several people familiar with the discussions.“We are deeply concerned about the situation in Afghanistan and the impact on the country’s development prospects, especially for women,” said David Theis, a spokesman for the World Bank. “We will continue to consult closely with the international community and development partners.”Dr. Majrooh said he had sent several emails and messages to representatives of the major donors, asking to discuss options for funding Sehatmandi, but he had not received an official response.“The ministry is left out of the communication chain, and somehow sidelined,” he said.The donors could fund the NGOs directly, set up an independent organization to manage the money, or route the money through the W.H.O. and other arms of the United Nations. The W.H.O. already funds health programs in many countries.Based on observations by its polio workers, the W.H.O. estimated last week that more than 90 percent of 2,200 health facilities for which they have information remained operational to some limited extent, and more than 90 percent of female health care workers — needed to to ensure that women can receive health services — were still showing up to work.“While this data is encouraging for the moment, we are obviously worried,” Dr. Brennan said. “It would be irresponsible not to plan for this and not to raise the alert.”

President Biden’s new coronavirus vaccine mandates will have sweeping ramifications for businesses, schools and the political discourse in the United States. But for many scientists, the question is a simpler one: Will these measures turn back a surging pandemic?The answer: Yes, in the longer term.It has become clear that the nation cannot hope to end the pandemic with some 37 percent of Americans not having received a single dose of Covid vaccine, several experts said in interviews. Cases and hospitalizations are only expected to rise as Americans move indoors in homes, schools and offices in the cooling weather.The administration’s new plan should stem the flood of infections and return the country to some semblance of normalcy over the longer term, the researchers said.“It’s going to fundamentally shift the arc of the current surge,” said Dr. Ashish Jha, dean of Brown University School of Public Health. “It’s exactly what’s needed at this moment.”The vaccine mandates will protect millions more people, particularly against severe disease, and relieve pressure on the health care system, said Natalie Dean, a biostatistician at Emory University. “It also sets a precedent for other organizations to make similar decisions” about mandates, she said.But some experts cautioned that the results from the aggressive plan would take many weeks to unfold. Immunization is not an instant process — at least six weeks for a two-dose vaccine — and the administration did not emphasize the measures that work more quickly: masking and widespread rapid testing, for example.The nation has been overtaken by the contagious Delta variant, a far more formidable foe than the original version of the virus. The optimism of the spring and early summer gave way to dread as experts observed the variant’s march across Asia and Europe, sending rates soaring even in Britain, which had successfully protected most of its older adults.The variant became the dominant version of the virus in the United States only in mid-July, and the consequences have been beyond anything experts predicted. Reassuringly low numbers of cases and hospitalizations in June have risen inexorably for weeks to nearly 10-fold their levels. About 1,500 Americans, the vast majority of them unvaccinated, are dying each day.The mandates arrived on Thursday after weeks of arguments from public health experts that the federal government must do much more to raise vaccination rates.The administration’s mandates will affect nearly 100 million Americans. Among them are health care workers. The administration will require that any provider receiving Medicaid or Medicare funding impose a vaccination requirement on staff.This is the measure mostly likely to have an immediate impact, experts said, because health care facilities are high-risk settings for transmission. And there is ample historical precedent for the decision to hold hospitals to certain standards — notably, the historical directive to desegregate patients by race, said Dr. Jha said.“We have a real dearth of leadership from health care systems that have not mandated within their own organizations, and it is imperative that the president require that patients be protected,” he added.The requirement may drive some health care and nursing home workers, particularly many who are close to retirement age, to leave the profession. Even so, there is more to be gained than lost by the mandates, said Dr. Nahid Bhadelia, founding director of Boston University’s Center for Emerging Infectious Diseases Policy and Research..css-1xzcza9{list-style-type:disc;padding-inline-start:1em;}.css-3btd0c{font-family:nyt-franklin,helvetica,arial,sans-serif;font-size:1rem;line-height:1.375rem;color:#333;margin-bottom:0.78125rem;}@media (min-width:740px){.css-3btd0c{font-size:1.0625rem;line-height:1.5rem;margin-bottom:0.9375rem;}}.css-3btd0c strong{font-weight:600;}.css-3btd0c em{font-style:italic;}.css-w739ur{margin:0 auto 5px;font-family:nyt-franklin,helvetica,arial,sans-serif;font-weight:700;font-size:1.125rem;line-height:1.3125rem;color:#121212;}#NYT_BELOW_MAIN_CONTENT_REGION .css-w739ur{font-family:nyt-cheltenham,georgia,’times new roman’,times,serif;font-weight:700;font-size:1.375rem;line-height:1.625rem;}@media (min-width:740px){#NYT_BELOW_MAIN_CONTENT_REGION .css-w739ur{font-size:1.6875rem;line-height:1.875rem;}}@media (min-width:740px){.css-w739ur{font-size:1.25rem;line-height:1.4375rem;}}.css-9s9ecg{margin-bottom:15px;}.css-16ed7iq{width:100%;display:-webkit-box;display:-webkit-flex;display:-ms-flexbox;display:flex;-webkit-align-items:center;-webkit-box-align:center;-ms-flex-align:center;align-items:center;-webkit-box-pack:center;-webkit-justify-content:center;-ms-flex-pack:center;justify-content:center;padding:10px 0;background-color:white;}.css-pmm6ed{display:-webkit-box;display:-webkit-flex;display:-ms-flexbox;display:flex;-webkit-align-items:center;-webkit-box-align:center;-ms-flex-align:center;align-items:center;}.css-pmm6ed > :not(:first-child){margin-left:5px;}.css-5gimkt{font-family:nyt-franklin,helvetica,arial,sans-serif;font-size:0.8125rem;font-weight:700;-webkit-letter-spacing:0.03em;-moz-letter-spacing:0.03em;-ms-letter-spacing:0.03em;letter-spacing:0.03em;text-transform:uppercase;color:#333;}.css-5gimkt:after{content:’Collapse’;}.css-rdoyk0{-webkit-transition:all 0.5s ease;transition:all 0.5s ease;-webkit-transform:rotate(180deg);-ms-transform:rotate(180deg);transform:rotate(180deg);}.css-eb027h{max-height:5000px;-webkit-transition:max-height 0.5s ease;transition:max-height 0.5s ease;}.css-6mllg9{-webkit-transition:all 0.5s ease;transition:all 0.5s ease;position:relative;opacity:0;}.css-6mllg9:before{content:”;background-image:linear-gradient(180deg,transparent,#ffffff);background-image:-webkit-linear-gradient(270deg,rgba(255,255,255,0),#ffffff);height:80px;width:100%;position:absolute;bottom:0px;pointer-events:none;}.css-uf1ume{display:-webkit-box;display:-webkit-flex;display:-ms-flexbox;display:flex;-webkit-box-pack:justify;-webkit-justify-content:space-between;-ms-flex-pack:justify;justify-content:space-between;}.css-wxi1cx{display:-webkit-box;display:-webkit-flex;display:-ms-flexbox;display:flex;-webkit-flex-direction:column;-ms-flex-direction:column;flex-direction:column;-webkit-align-self:flex-end;-ms-flex-item-align:end;align-self:flex-end;}.css-12vbvwq{background-color:white;border:1px solid #e2e2e2;width:calc(100% – 40px);max-width:600px;margin:1.5rem auto 1.9rem;padding:15px;box-sizing:border-box;}@media (min-width:740px){.css-12vbvwq{padding:20px;width:100%;}}.css-12vbvwq:focus{outline:1px solid #e2e2e2;}#NYT_BELOW_MAIN_CONTENT_REGION .css-12vbvwq{border:none;padding:10px 0 0;border-top:2px solid #121212;}.css-12vbvwq[data-truncated] .css-rdoyk0{-webkit-transform:rotate(0deg);-ms-transform:rotate(0deg);transform:rotate(0deg);}.css-12vbvwq[data-truncated] .css-eb027h{max-height:300px;overflow:hidden;-webkit-transition:none;transition:none;}.css-12vbvwq[data-truncated] .css-5gimkt:after{content:’See more’;}.css-12vbvwq[data-truncated] .css-6mllg9{opacity:1;}.css-qjk116{margin:0 auto;overflow:hidden;}.css-qjk116 strong{font-weight:700;}.css-qjk116 em{font-style:italic;}.css-qjk116 a{color:#326891;-webkit-text-decoration:underline;text-decoration:underline;text-underline-offset:1px;-webkit-text-decoration-thickness:1px;text-decoration-thickness:1px;-webkit-text-decoration-color:#326891;text-decoration-color:#326891;}.css-qjk116 a:visited{color:#326891;-webkit-text-decoration-color:#326891;text-decoration-color:#326891;}.css-qjk116 a:hover{-webkit-text-decoration:none;text-decoration:none;}“This is an important step to get us out of the pandemic,” she said. “The very people who are taking care of the vulnerable coming into the hospital need to be our first line of defense.”The Labor Department will require all private-sector businesses with more than 100 employees to require that their workforces be fully vaccinated or be tested at least once a week. Employers will be required to give paid time off to employees to get vaccinated.That move alone will affect 80 million Americans; it’s not clear how many are already vaccinated. In any event, the effects will not be immediately evident.Given the time required between the first two doses of the vaccine, and then for immunity to build up, the effect of all these mandates is unlikely to be felt for many weeks, said Bill Hanage, an epidemiologist at Harvard University.And Dr. Hanage was skeptical that the mandates would be successful in inoculating millions more people than have already opted for the vaccine. Some of the people who most urgently need to be protected are older adults who will not be affected by workplace requirements.“I’m sure that the anti-vaxxers are already prepared to be up in arms about this,” he said. (Republican governors in several states have decried the mandates as unconstitutional and say they plan to file suits to stop them.)By insisting that vaccination is the way out of the pandemic, officials in both the Trump and Biden administrations have de-emphasized the importance of masks and testing in controlling the pandemic, several experts said.“It’s a lot quicker to put on a mask than it is to get a bunch of people vaccinated,” Dr. Hanage said.

Prevention and treatment fell in poor countries last year as access to health care declined, according to a new report.The Covid-19 pandemic has severely set back the fight against other global scourges like H.I.V., tuberculosis and malaria, according to a sobering new report released on Tuesday.Before the pandemic, the world had been making strides against these illnesses. Overall, deaths from those diseases have dropped by about half since 2004.“The advent of a fourth pandemic, in Covid, puts these hard-fought gains in great jeopardy,” said Mitchell Warren, executive director of AVAC, a nonprofit organization promoting H.I.V. treatment worldwide.The pandemic has flooded hospitals and disrupted supply chains for tests and treatments. In many poor countries, the coronavirus diverted limited public health resources away from treatment and prevention of these diseases.Many fewer people sought diagnosis or medication, because they were afraid of becoming infected with the coronavirus at clinics. And some patients were denied care because their symptoms of a cough or fever resembled those of Covid-19.Unless comprehensive efforts to beat back the illnesses resume, “we’ll continue to play emergency response and global health whack-a-mole,” Mr. Warren said.The report was compiled by the Global Fund, an advocacy group that funds campaigns against H.I.V., malaria and tuberculosis.Before the arrival of the coronavirus, TB was the biggest infectious-disease killer worldwide, claiming more than one million lives each year. The pandemic has exacerbated the damage.In 2020, about one million fewer people were tested and treated for TB, compared with 2019 — a drop of about 18 percent, according to the new report.The number of people treated for drug-resistant TB declined by 19 percent, and for extensively drug-resistant TB, by 37 percent. Nearly 500,000 people were diagnosed with drug-resistant TB in 2019.“We’ve been hit really hard on TB,” said Peter Sands, executive director of the Global Fund. “I’m afraid that inevitably means hundreds of thousands of extra deaths.”India, which has the highest TB burden in the world, had resumed its pre-Covid rate of TB diagnoses by late 2020, but the outbreak this spring is likely to have reversed that progress, Mr. Sands said.A drop in TB diagnoses can have far-reaching consequences for a community. One person with untreated TB can spread the bacteria to as many as 15 people each year.Compared with 2019, the number of people who sought testing for H.I.V. declined by 22 percent, and those who opted for H.I.V. prevention services by 12 percent. Medical male circumcision, thought to slow the spread of the virus, decreased by 27 percent.“Because there isn’t a cure for H.I.V., every single person who gets infected is a long-term impact,” Mr. Sands said.Diagnoses of malaria fell by a small amount, according to the report. Most countries were able to implement measures that limited the impact on diagnosis and treatment.As many as 115 million people have been driven into extreme poverty because of Covid-19, further limiting their access to treatment and support. In some countries, school closures and lockdowns made it particularly difficult for adolescent girls and young women to receive health services.There were a few glimmers of hope amid the bleak news: The crisis forced health agencies and ministries in many poor countries to adopt innovations that may outlast the pandemic. Among them: dispensing to patients multi-month supplies of TB and H.I.V. drugs, or of condoms, lubricants and needles; using digital tools to monitor TB treatment; and testing simultaneously for H.I.V., TB and Covid-19.For example, in Nigeria, community health workers who tested people for Covid also looked for cases of H.I.V. and TB. As a result, the country became one of the few to see a rise in H.I.V. diagnoses compared with 2019.In Ouagadougou, Burkina Faso, community health workers on motorbikes delivered insecticide-treated bed nets door to door, rather than distributing them from trucks in village squares, allowing them to reach more households than before, and cutting down the number of malaria infections.“It’s a bit more expensive” to deliver nets to individual households, but “that was an investment that was clearly worth doing,” Mr. Sands said.To minimize the impact of the pandemic, the Global Fund has spent about $1 billion more than its usual budget, Mr. Sands said. In March 2020, the organization released $500 million to help countries cope; as of August 2021, it has raised $3.3 billion for use in 107 countries.The funds have been used to shore up health systems, provide tests, treatments and oxygen, and to give personal protective equipment to health care workers.Donors have committed to provide another $6 billion for H.I.V. and $2 billion for TB over the next three years, Mr. Sands said.

As the pandemic takes an unexpected direction, Americans again must reckon with twists in scientific understanding of the virus.When the coronavirus surfaced last year, no one was prepared for it to invade every aspect of daily life for so long, so insidiously. The pandemic has forced Americans to wrestle with life-or-death choices every day of the past 18 months — and there’s no end in sight.Scientific understanding of the virus changes by the hour, it seems. The virus spreads only by close contact or on contaminated surfaces, then turns out to be airborne. The virus mutates slowly, but then emerges in a series of dangerous new forms. Americans don’t need to wear masks. Wait, they do.At no point in this ordeal has the ground beneath our feet seemed so uncertain. In just the past week, federal health officials said they would begin offering booster shots to all Americans in the coming months. Days earlier, those officials had assured the public that the vaccines were holding strong against the Delta variant of the virus, and that boosters would not be necessary.As early as Monday, the Food and Drug Administration is expected to formally approve the Pfizer-BioNTech vaccine, which has already been given to scores of millions of Americans. Some holdouts found it suspicious that the vaccine was not formally approved yet somehow widely dispensed. For them, “emergency authorization” has never seemed quite enough.Americans are living with science as it unfolds in real time. The process has always been fluid, unpredictable. But rarely has it moved at this speed, leaving citizens to confront research findings as soon as they land at the front door, a stream of deliveries that no one ordered and no one wants.Is a visit to my ailing parent too dangerous? Do the benefits of in-person schooling outweigh the possibility of physical harm to my child? Will our family gathering turn into a superspreader event?Living with a capricious enemy has been unsettling even for researchers, public health officials and journalists who are used to the mutable nature of science. They, too, have frequently agonized over the best way to keep themselves and their loved ones safe.But to frustrated Americans unfamiliar with the circuitous and often contentious path to scientific discovery, public health officials have seemed at times to be moving the goal posts and flip-flopping, or misleading, even lying to, the country.Most of the time, scientists are “edging forward in a very incremental way,” said Richard Sever, assistant director of Cold Spring Harbor Laboratory Press and a co-founder of two popular websites, bioRxiv and medRxiv, where scientists post new research.“There are blind alleys that people go down, and a lot of the time you kind of don’t know what you don’t know.”Biology and medicine are particularly demanding fields. Ideas are evaluated for years, sometimes decades, before they are accepted.Cathy and Mark Baum visited Mr. Baum’s mother at an assisted living center in Reston, Va., in 2020. Alyssa Schukar for The New York TimesResearchers first frame the hypothesis, then design experiments to test it. Data from hundreds of studies, often by competing teams, are analyzed before the community of experts comes to a conclusion.In the interim, scientists present the findings to their peers, often at niche conferences that are off-limits to journalists and the general public, and hone their ideas based on the feedback they receive. It’s not unusual to see attendees at these meetings point out — sometimes harshly — every flaw in a study’s methods or conclusions, sending the author back to the lab for more experiments.Fifteen years elapsed from the description of the first cases of H.I.V. to the identification of two proteins the virus needs to infect cells, a finding crucial to research for a cure. Even after a study has reached a satisfying conclusion, it must be submitted for rigorous review at a scientific journal, which can add another year or more before the results become public.Measured on that scale, scientists have familiarized themselves with the coronavirus at lightning speed, partly by accelerating changes to this process that were already underway.Treatment results, epidemiological models, virological discoveries — research into all aspects of the pandemic turns up online almost as quickly as authors can finish their manuscripts. “Preprint” studies are dissected online, particularly on Twitter, or in emails between experts.What researchers have not done is explain, in ways that the average person can understand, that this is how science has always worked.The public disagreements and debates played out in public, instead of at obscure conferences, give the false impression that science is arbitrary or that scientists are making things up as they go along.“What a non-scientist or the layperson doesn’t realize is that there is a huge bolus of information and consensus that the two people who are arguing will agree upon,” Dr. Sever said.Is it really so surprising, then, that Americans feel bewildered and bamboozled, even enraged, by rapidly changing rules that have profound implications for their lives?Demonstrators opposed to vaccine mandates outside Duke Hospital in Durham, N.C., in July.Cornell Watson for The New York TimesFederal agencies have an unenviable task: Creating guidelines needed to live with an unfamiliar and rapidly spreading virus. But health officials have not acknowledged clearly or often enough that their recommendations may — and very probably would — change as the virus, and their knowledge of it, evolved.“Since the beginning of this pandemic, it’s been a piss-poor job, to say it in the nicest way,” said Dr. Syra Madad, an infectious disease epidemiologist at the Belfer Center for Science and International Affairs at Harvard.Leaders in the United States and Britain have promised too much too soon, and have had to backtrack. Health officials have failed to frame changing advice as necessary when scientists learn more about the virus.And the officials have not really defined the pandemic’s end — for example, that the virus will finally loosen its stranglehold once the infections drop below a certain mark. Without a clearly delineated goal, it can seem as if officials are asking people to give up their freedoms indefinitely.One jarring backtrack was the mask guidance by the Centers for Disease Control and Prevention. The agency said in May that vaccinated people could drop their masks, advice that helped set the stage for a national reopening. Officials did not emphasize, or at least not enough, that the masks could be needed again. Now, with a new surge in infections, they are.“It can be really difficult for public perception and public understanding when these big organizations seem to reverse course in a way that is really not clear,” said Ellie Murray, a science communicator and public health expert at Boston University.It does not help that the C.D.C. and the World Health Organization, the two leading public health agencies, have disagreed as frequently as they have in the past 18 months — on the definition of a pandemic, on the frequency of asymptomatic infections, on the safety of Covid-19 vaccines for pregnant women.Most Americans have a decent grasp of basic health concepts — exercise is good, junk food is bad. But many are never taught how science progresses.People signed up to receive their first shot of the Pfizer-BioNTech vaccine in Queens this month.Byron Smith for The New York TimesIn 2018, 15-year-olds in the United States ranked 18th in their ability to explain scientific concepts, lagging behind their peers in not just China, Singapore and the United Kingdom, but also Poland and Slovenia.In a 2019 survey by the Pew Research Center, many Americans correctly identified fossil fuels and the rising threat of antibiotic resistance, but they were less knowledgeable about the scientific process..css-1xzcza9{list-style-type:disc;padding-inline-start:1em;}.css-3btd0c{font-family:nyt-franklin,helvetica,arial,sans-serif;font-size:1rem;line-height:1.375rem;color:#333;margin-bottom:0.78125rem;}@media (min-width:740px){.css-3btd0c{font-size:1.0625rem;line-height:1.5rem;margin-bottom:0.9375rem;}}.css-3btd0c strong{font-weight:600;}.css-3btd0c em{font-style:italic;}.css-w739ur{margin:0 auto 5px;font-family:nyt-franklin,helvetica,arial,sans-serif;font-weight:700;font-size:1.125rem;line-height:1.3125rem;color:#121212;}#NYT_BELOW_MAIN_CONTENT_REGION .css-w739ur{font-family:nyt-cheltenham,georgia,’times new roman’,times,serif;font-weight:700;font-size:1.375rem;line-height:1.625rem;}@media (min-width:740px){#NYT_BELOW_MAIN_CONTENT_REGION .css-w739ur{font-size:1.6875rem;line-height:1.875rem;}}@media (min-width:740px){.css-w739ur{font-size:1.25rem;line-height:1.4375rem;}}.css-9s9ecg{margin-bottom:15px;}.css-16ed7iq{width:100%;display:-webkit-box;display:-webkit-flex;display:-ms-flexbox;display:flex;-webkit-align-items:center;-webkit-box-align:center;-ms-flex-align:center;align-items:center;-webkit-box-pack:center;-webkit-justify-content:center;-ms-flex-pack:center;justify-content:center;padding:10px 0;background-color:white;}.css-pmm6ed{display:-webkit-box;display:-webkit-flex;display:-ms-flexbox;display:flex;-webkit-align-items:center;-webkit-box-align:center;-ms-flex-align:center;align-items:center;}.css-pmm6ed > :not(:first-child){margin-left:5px;}.css-5gimkt{font-family:nyt-franklin,helvetica,arial,sans-serif;font-size:0.8125rem;font-weight:700;-webkit-letter-spacing:0.03em;-moz-letter-spacing:0.03em;-ms-letter-spacing:0.03em;letter-spacing:0.03em;text-transform:uppercase;color:#333;}.css-5gimkt:after{content:’Collapse’;}.css-rdoyk0{-webkit-transition:all 0.5s ease;transition:all 0.5s ease;-webkit-transform:rotate(180deg);-ms-transform:rotate(180deg);transform:rotate(180deg);}.css-eb027h{max-height:5000px;-webkit-transition:max-height 0.5s ease;transition:max-height 0.5s ease;}.css-6mllg9{-webkit-transition:all 0.5s ease;transition:all 0.5s ease;position:relative;opacity:0;}.css-6mllg9:before{content:”;background-image:linear-gradient(180deg,transparent,#ffffff);background-image:-webkit-linear-gradient(270deg,rgba(255,255,255,0),#ffffff);height:80px;width:100%;position:absolute;bottom:0px;pointer-events:none;}.css-uf1ume{display:-webkit-box;display:-webkit-flex;display:-ms-flexbox;display:flex;-webkit-box-pack:justify;-webkit-justify-content:space-between;-ms-flex-pack:justify;justify-content:space-between;}.css-wxi1cx{display:-webkit-box;display:-webkit-flex;display:-ms-flexbox;display:flex;-webkit-flex-direction:column;-ms-flex-direction:column;flex-direction:column;-webkit-align-self:flex-end;-ms-flex-item-align:end;align-self:flex-end;}.css-12vbvwq{background-color:white;border:1px solid #e2e2e2;width:calc(100% – 40px);max-width:600px;margin:1.5rem auto 1.9rem;padding:15px;box-sizing:border-box;}@media (min-width:740px){.css-12vbvwq{padding:20px;width:100%;}}.css-12vbvwq:focus{outline:1px solid #e2e2e2;}#NYT_BELOW_MAIN_CONTENT_REGION .css-12vbvwq{border:none;padding:10px 0 0;border-top:2px solid #121212;}.css-12vbvwq[data-truncated] .css-rdoyk0{-webkit-transform:rotate(0deg);-ms-transform:rotate(0deg);transform:rotate(0deg);}.css-12vbvwq[data-truncated] .css-eb027h{max-height:300px;overflow:hidden;-webkit-transition:none;transition:none;}.css-12vbvwq[data-truncated] .css-5gimkt:after{content:’See more’;}.css-12vbvwq[data-truncated] .css-6mllg9{opacity:1;}.css-qjk116{margin:0 auto;overflow:hidden;}.css-qjk116 strong{font-weight:700;}.css-qjk116 em{font-style:italic;}.css-qjk116 a{color:#326891;-webkit-text-decoration:underline;text-decoration:underline;text-underline-offset:1px;-webkit-text-decoration-thickness:1px;text-decoration-thickness:1px;-webkit-text-decoration-color:#326891;text-decoration-color:#326891;}.css-qjk116 a:visited{color:#326891;-webkit-text-decoration-color:#326891;text-decoration-color:#326891;}.css-qjk116 a:hover{-webkit-text-decoration:none;text-decoration:none;}And basic tenets of public health often are even more of a mystery: How does my behavior affect others’ health? Why should I be vaccinated if I consider myself low-risk?“People weren’t primed before to understand a lot of these concepts,” Dr. Madad said. “We should have known that we couldn’t expect the public to change their behaviors on a dime.”Both information and disinformation about Covid-19 surface online, especially on social media, much more now than in previous public health crises. This represents a powerful opportunity to fill in the knowledge gaps for many Americans.But health officials have not taken full advantage. The C.D.C.’s Twitter feed is a robotic stream of announcements. Agency experts need not just to deliver messages, but also to answer questions about how the evolving facts apply to American lives.And health officials need to be more nimble, so that bad actors don’t define the narrative while real advice is delayed by a traditionally cumbersome bureaucracy.“They’re not moving at the speed that this pandemic is moving,” Dr. Murray said. “That obviously creates a perception in the public that you can’t just rely on those more official sources of news.”The first day of school at an elementary school in Newark, Calif., this month.Clara Mokri for The New York TimesIn the middle of a pandemic, health officials have some responsibility to counter the many spurious voices on Twitter and Facebook spreading everything from pseudoscience to lies. Risk communication during a public health crisis is a particular skill, and right now Americans need the balm.“There are some people whose confidence outweighs their knowledge, and they’re happy to say things which are wrong,” said Helen Jenkins, an infectious disease expert at Boston University.“And then there are other people who probably have all the knowledge but keep quiet because they’re scared of saying things, which is a shame as well, or just aren’t good communicators.”Health officials could begin even now with two-minute videos to explain basic concepts; information hotlines and public forums at the local, state and federal levels; and a responsive social media presence to counter disinformation.The road ahead will be difficult. The virus has more surprises in store, and the myths that have already become entrenched will be hard to erase.But it’s not too much to hope that the lessons learned in this pandemic will help experts explain future disease outbreaks, as well as other urgent problems, like climate change, in which individual actions contribute to the whole.The first step toward educating the public and winning their trust is to make plans, and then communicate them honestly — flaws, uncertainty and all.