Coronavirus UpdatesMany U.S. States With Bad Recent Outbreaks Show Case and Hospitalization Drops

Many of the states that have suffered the worst recent coronavirus outbreaks have seen notable declines both in new cases and in hospitalizations over the last two weeks, according to a New York Times database.

For example, in Michigan, which has had one of the country’s steepest drops, the average number of daily cases sank 44 percent and hospitalizations tumbled 33 percent over that time period, as of Tuesday.

The average number of new cases is also down 32 percent in Minnesota, 38 percent in Pennsylvania and 36 percent in Florida in the past two weeks. In the same three states, hospitalizations are down 21 percent, 28 percent and 12 percent.

The progress for states like Michigan, which recently began to recover from one of its worst stretches in the pandemic, could indicate that vaccinations are beginning to rein in the virus in the United States. Hospitalization data can often lag behind case numbers for a number of reasons.

The director of the Centers for Disease Control and Prevention, Dr. Rochelle Walensky, testified at a Senate hearing on Tuesday that while she was encouraged by the gains against the pandemic, she urged Americans to remain vigilant to the threat of the virus around the world.

Ms. Walensky said getting a vaccine was the fastest way to end the pandemic.

“But even with this powerful tool, while we continue to have community transmission, we must also maintain public health measures we know will prevent the spread of this virus, mask hygiene, hand hygiene, and physical distancing,” she said.

Dr. Michael Osterholm, director of the Center for Infectious Disease Research and Policy at the University of Minnesota, said in an interview that the vaccines were a key contributor to improvements in case numbers and hospitalizations, but that the virus had behaved in surprising ways and there remained aspects about which experts still needed to learn more.

As an example of the virus’s unpredictable ebbs and flows, Dr. Osterholm pointed to Indiana, which borders Michigan and has lower vaccination rates but did not see the same recent spike in case numbers as its northern neighbor.

“I don’t see us having a national surge. We’re not going to be like India. I do think the vaccine levels have surely helped us tremendously in taking that off the table,” Dr. Osterholm said. “But I do think at the state level, where we have substantial populations that need to be vaccinated, we could still see substantial activity.”

After reaching an average peak of 3.38 million doses reported a day in mid-April, the pace of U.S. coronavirus vaccinations had declined. Nearly all states have a supply of vaccine doses that could be quickly redirected to adolescents. On Wednesday, the federal government took a final step toward making the Pfizer-BioNTech vaccine available to 12- to 15-year-olds.

President Biden is pursuing a strategy focused on local outreach and expanded accessibility to the vaccine to help reach his goal of at least partly vaccinating 70 percent of Americans by Independence Day.

“If it’s available, if it’s nearby, if it’s convenient, people are getting vaccinated,” Mr. Biden said at the White House on Wednesday, highlighting initiatives like walk-up availability and free Uber and Lyft rides to vaccination sites.

Making it easier to get vaccinated could appeal to the roughly 30 million Americans who say they would get the shot, but have not yet done so for myriad reasons. Local officials and private businesses are also offering a wide range of different incentives, like free subway rides, beer, baseball tickets and cash payouts, to convince more reluctant Americans to get vaccinated.

The changes in the trajectory of the virus in the United States come as other regions of the world, especially India and Southeast Asia, are getting hit hard. A number of variants are also spreading around the world, and scientists told a U.S. congressional panel on Wednesday that variants will pose a continuing threat to the nation.

Dr. Tedros Adhanom Ghebreyesus, the director general of the W.H.O., said on Monday that the world was seeing a plateau in known cases, “but it is an unacceptably high plateau with more than 5.4 million cases and almost 90,000 deaths last week.”

He continued, “Any decline is welcome but we have been here before, over the past year many countries have experienced a declining trend in cases and deaths, have relaxed public health and social measures too quickly, and individuals have let down their guard only for those hard-won gains to be lost.”

Bryan Pietsch contributed reporting.

Two top executives of Emergent BioSolutions, a previously obscure Maryland biotech firm whose Baltimore plant ruined millions of doses of coronavirus vaccine, have agreed to testify on Capitol Hill next week as part of a congressional investigation into their company, a politically connected federal contractor.

Fuad El-Hibri, the company’s founder and executive chairman, and Robert Kramer, its chief executive officer, will appear on May 19 before the House Select Subcommittee on the Coronavirus, committee officials said on Wednesday morning. The panel has opened a sprawling inquiry into Emergent’s manufacturing failures, and whether the company used its contacts with the Trump administration to land hundreds of millions of dollars in coronavirus vaccine contracts.

“Emergent’s actions wasted American taxpayer dollars and reduced the number of doses available for global vaccination efforts,” Representative Jim Clyburn, Democrat of South Carolina and the subcommittee’s chairman, said in a statement to The Times. He said that Congress “is looking for answers and they are long overdue.”

An investigation by The New York Times, published in March before the firm’s vaccine manufacturing troubles were known, examined Emergent’s aggressive lobbying tactics and lucrative relationship with the federal government.

The hearing will put an unwelcome spotlight on the company, which kept a low profile over the past two decades as it cornered the market on sales of anthrax vaccines and other bioterror-related products to the Strategic National Stockpile, the nation’s emergency medical reserve.

Emergent’s stock performed so well in 2020 that Mr. El-Hibri cashed in shares and options worth over $42 million, corporate filings show. Mr. Kramer, who has boasted to investors that “extensive relationships across multiple agencies within the federal government” helped build the company, took home a $1.2 million cash bonus and $2 million in stock awards.

In an interview with CNN on Wednesday morning, Mr. Clyburn indicated that the committee was also scrutinizing the executives’ market moves. “They all made millions in stock transactions while they seem to be hiding stuff from the public,” he said.

The Times reported last month that workers at Emergent’s Baltimore plant had accidentally conflated the ingredients of two coronavirus vaccines, one by Johnson & Johnson and the other by AstraZeneca. The error resulted in the loss of up to 15 million Johnson & Johnson doses, and a recent inspection by the Food and Drug Administration said that more doses may have been exposed to contamination.

In a statement on Wednesday, the company said that it had responded to the F.D.A.’s observations with a “comprehensive quality enhancement plan” and had “already started making improvements.”

On a recent call with investors, Mr. Kramer announced a management shake-up and said that while the company had “implemented multiple layers of disinfection and other protocols to lessen the inherent risk of cross-contamination” when manufacturing two vaccines in the same plant, the precautions “did not function as anticipated.” He took “full responsibility” for the manufacturing problems that ensued, acknowledging that the “loss of a batch for a viral contamination is extremely serious, and we treated it as such.”

In letters to the two Emergent executives last month, Mr. Clyburn and Representative Carolyn Maloney, Democrat of New York and chairwoman of the House Oversight and Reform Committee, demanded a slew of documents, including any correspondence between the company and Dr. Robert Kadlec, President Trump’s assistant secretary for preparedness and response, who previously consulted for the company. In interviews, Dr. Kadlec has said his consulting work, in 2013 and 2014, was limited and did not affect contracting decisions.

“Emergent has been in the news a lot lately, and that’s frankly not something we’re used to,” Mr. Kramer wrote in a commentary posted on the company’s website last month. “Until a year ago we were a little-known company that does our work behind the scenes.”

The company is trying to burnish its image with television and digital advertising, as part of a campaign it is calling “We Go.” The 30-second ads feature images of white-clad lab technicians and spotlight some of the company’s lesser-known work manufacturing cholera vaccines and medicine used to treat opioid overdoses, as well as its Covid-19 work.

Emergent’s plant in Baltimore is one of two federally designated Centers for Innovation in Advanced Development and Manufacturing, funded in part by taxpayers. In June 2020, the federal government awarded Emergent a $628 million contract, largely to reserve space for coronavirus vaccine manufacturing, despite staffing and quality concerns.

The Biden administration responded to the potential contamination last month by putting Johnson & Johnson in charge of the Baltimore facility and moving out AstraZeneca. Doses made at the plant have not been cleared for use in the United States, and millions of shots made in Baltimore and sent overseas have also been put on hold.

The federal government on Wednesday took a final step toward making the Pfizer-BioNTech coronavirus vaccine available to 12- to 15-year-olds in the United States, removing an obstacle to school reopenings and cheering millions of families weary of pandemic restrictions.

An advisory committee to the Centers for Disease Control and Prevention voted to recommend the vaccine for use in children in that age group. The C.D.C. director, Dr. Rochelle Walensky, formally adopted the recommendation on Wednesday evening.

Many parents are eagerly anticipating the availability of vaccines for children, at least in part to speed their return to schools. Roughly one-third of eighth graders, usually 13 or 14 years old, are still learning fully remotely.

Vaccinations of adolescents have already begun in a few states, like Maine. Others plan to offer the vaccine as early as Thursday. There are nearly 17 million 12- to 15-year-olds in the United States, accounting for 5.3 percent of the population.

Nearly all states now have vaccine supply that could be quickly redirected to adolescents. The dose used to immunize adults is also safe and effective for these adolescents, clinical trials have shown.

While children’s risk of severe illness is low compared with that of adults, the coronavirus has infected more than 1.5 million children and sent more than 13,000 to hospitals, more than are hospitalized for flu in an average year, according to data collected by the C.D.C.

Young children are thought to spread the virus less often than adults do, but their ability to transmit increases with age. Teenagers, particularly those in high school, may transmit the virus as readily as adults. Children aged 12 to 17 years represent an increasing proportion of Covid cases in the country.

Vaccinating children should increase the level of immunity in the U.S. population, helping to bring down the number of cases.

In remarks from the White House on Wednesday, President Biden touted the benefits of a vaccine for children 12 and older as “safe, effective, easy, fast and free.”

“My hope is parents will take advantage of the vaccine and get their kids vaccinated,” he said. He noted that “as of tomorrow, more than 15,000 pharmacies will be ready to vaccinate this age group,” and that pharmacies would make it easy for teens moving around to get the first shot in one location and a second shot elsewhere.

Mr. Biden also expressed skepticism about continued vaccine hesitancy. “If it’s available, if it’s nearby, if it’s convenient, people are getting vaccinated,” he said. “I believe the vast majority of Americans will get vaccinated.”

Pfizer announced in March that the vaccine seemed to be at least as effective in 12- to 15-year-olds as it has been in older teenagers and adults. Apart from a slight increase in the frequency of fevers, the shots also seemed to have comparable, mostly negligible side effects.

The Food and Drug Administration reviewed the clinical data and on Monday authorized the Pfizer vaccine for use in these children, capping weeks of anticipation from parents and children about a swifter return to normalcy.

Annie Karni contributed reporting.

To the many inducements that governments have used to try to bolster slumping demand for the coronavirus vaccine, Gov. Mike DeWine of Ohio raised the ante considerably on Wednesday, announcing a weekly state lottery that would give five people $1 million each in return for having been vaccinated.

The lottery, whose legality could raise questions, will be paid for with federal coronavirus relief funds, Mr. DeWine, a Republican, said during a statewide televised address.

The first of five weekly drawings will be conducted by the Ohio Lottery on May 26, he said.

“I know that some may say, ‘DeWine, you’re crazy!’ ” the governor posted on Twitter. “‘This million-dollar drawing idea of yours is a waste of money.’ But truly, the real waste at this point in the pandemic — when the vaccine is readily available to anyone who wants it — is a life lost to COVID-19.”

The next time the world faces an outbreak of a fast-spreading and deadly new pathogen, governments must act swiftly and be ready to restrict travel or mandate masks even before anyone knows the extent of the threat, according to a pair of new reports delivered to the World Health Organization.

The studies are intended to address missteps over the past year that led to more than 3.25 million deaths, some $10 trillion in economic losses and more than 100 million people pushed into extreme poverty.

“Current institutions, public and private, failed to protect people from a devastating pandemic,” concluded one of the reports, released on Wednesday, which called the Covid-19 pandemic “the 21st century’s Chernobyl moment.”

“Without change,” it said, these institutions “will not prevent a future one.”

The reviews, released in advance of this month’s meeting of the W.H.O.’s governing assembly, were written by appointees who donated countless hours in the midst of their own countries’ pandemic fights to interview hundreds of experts, comb through thousands of documents, gather data and seek counsel from public and private institutions around the world.

Pandemics, the authors concluded, are an existential threat on the order of a chemical or nuclear weapon, and preparing for them must be the responsibility of the highest levels of political leadership rather than only health departments, which are often among the least powerful of government agencies.

The slowdown in vaccinations across the United States is often attributed to a blend of misinformation and mistrust among Americans known as “vaccine hesitancy.”

But a sizable number of people — some 30 million, by a new U.S. census estimate — remain unvaccinated even though they are not hesitant or skeptical. They just haven’t managed to get a shot, for a host of reasons.

These people outnumber the truly hesitant — the more than 28 million who said they would probably or definitely not get vaccinated — and also the 16 million who said they were unsure. And they became an official new focus of the nation’s mass vaccination campaign this month.

In addition to “the doubters,” President Biden said at a press briefing last week, the mission is to get the vaccine to those who are “just not sure how to get to where they want to go.”

For the most part, they are working-class people with jobs and family obligations that leave them little discretionary time. Many have health issues or disabilities, or face language barriers that can make getting inoculated against Covid seem daunting. Others don’t have a regular doctor, and some are socially isolated.

Technically, they have access to the vaccine. Practically, it’s not that simple.

“Hesitancy makes a better story because you’ve got controversy,” said Tom Frieden, a former director of the Centers for Disease Control and Prevention. “But there’s a bigger problem of access than there is of hesitancy.”

On May 4, Dr. Hina Talib, who goes by the handle @teenhealthdoc on Instagram, asked the parents among her 33,000 followers if they were hesitant to get the coronavirus vaccine for their 12- to 15-year-olds, and if so, why. Dr. Talib, a physician in the adolescent medicine division at the Children’s Hospital at Montefiore in New York, got 600 messages in response.

More often than not, Dr. Talib said, the parents had already had the Covid-19 vaccine, and would preface their message with: “I’m not an anti-vaxxer or an anti-masker. I’m just worried.”

Trials have shown no serious safety concerns for children thus far, and an advisory committee to the Centers for Disease Control and Prevention voted on Wednesday to recommend the vaccine for use in children age 12 to 15. The C.D.C. director, Dr. Rochelle Walensky, formally adopted the recommendation on Wednesday evening.

But some recent polls show that only about 30 percent of parents across the United States say they would get their children vaccinated right away. Parents of infants and preschoolers expressed even more anxiety about the vaccine than parents of teenagers.

These parents tend to be concerned about the vaccine affecting puberty and future fertility for their children, and its possible impact on allergies and side effects. Their fears are a key hurdle for U.S. efforts to expand vaccinations to younger teens.

Coronavirus variants will pose a continuing threat to the United States, with the potential to spread quickly and blunt the effectiveness of vaccines, scientists told a House panel on Wednesday.

“We must ensure that the tools we use to detect, treat, and forecast the virus are keeping up with emerging variants,” said Rep. Bill Foster, Democrat of Illinois and the chairman of the House subcommittee that heard the scientists’ testimony.

Last month, the White House announced almost $2 billion in funding for tracking coronavirus variants. The plan calls for large-scale sequencing of virus genomes, as well as research to understand how mutations alter the biology of viruses.

The funding is needed urgently, said Salim S. Abdool Karim, a professor of clinical epidemiology at the Mailman School of Public Health at Columbia University. “Over the coming months, we can reasonably expect new variants to emerge that are able to escape vaccine-induced immunity, because the virus is being put under pressure from wide-scale vaccination,” he said.

The world is not doing enough to track such variants, said Nathan Grubaugh, an epidemiologist at the Yale School of Public Health. “These global and national genomic surveillance gaps severely limit our ability to detect new and emerging SARS-CoV-2 variants, and should be considered as a threat to U.S. public health,” he said.

In addition to sequencing more genomes, scientists said that they needed ways to share their data quickly. That data should include more than just mutations carried by viruses, according to Caitlin Rivers, a senior scholar at the Johns Hopkins Center for Health Security. Dr. Rivers said that scientists also needed a way to learn about the health of people after they get infected with variants.

“We must be able to observe how the variant behaves in individuals and populations,” Dr. Rivers said.

For example, when New York researchers connected information about B.1.526, a variant common in the city, with medical records, they found that it does not make people unusually sick with Covid-19.

By monitoring variants, Dr. Rivers said, researchers could offer early warnings about threats to the protection afforded by vaccines. Vaccine developers could then respond by creating formulations tailored to the variants.

“We must not again be unprepared,” Dr. Rivers warned.

If you’ve enjoyed working from home during the pandemic — no commute, cooking lunch in your own kitchen or being around family more often — the chief executive of WeWork has some thoughts about you.

“Those who are least engaged are very comfortable working from home,” Sandeep Mathrani, the C.E.O. of WeWork said at a Wall Street Journal event on Wednesday. “Those who are überly engaged with the company want to go to the office two-thirds of the time, at least.”

“People are happier when they come to work,” he added. The company is betting on people wanting to — or being required to — work outside of their homes once it is safe to do so widely.

His comments were not received well by many online as many companies and employees consider the post-Covid-19 workplace after more than a year of doing their jobs from home.

“I wonder why the C.E.O. of a company that rents office space would say this,” wrote one Twitter user.

Others noted that working from home has benefited parents and has improved some workers’ mental health.

Ann Johnson, a corporate vice president at Microsoft, wrote: “If the only way you can keep your employees engaged is by being in the office with them, you have a leadership issue — not an employee engagement issue.”

Google said this month that it would relax its remote work protocols and that it expected 20 percent of its employees to work remotely after its offices reopen. The tech giant had previously been one of the industry’s holdouts on flexible remote work, and Insider reported that some employees had threatened to quit if they couldn’t keep working from home.

Federal health officials have now confirmed 28 cases, including six in men, of a rare blood clotting disorder in adults who have received the Johnson & Johnson Covid-19 vaccine.

Dr. Tom Shimabukuro, the deputy director of the immunization safety office at the Centers for Disease Control and Prevention, presented the new cases on Wednesday at a meeting of a panel of advisers to the C.D.C.

The figure is an increase from the 15 confirmed cases, all of which were in women, that were reported at last month’s meeting.

Although officials have now identified a handful of cases in men, women — especially those between the ages of 30 and 49 — appear to remain at elevated risk. “The trend is that the reporting rates are higher in females compared to males in all age categories,” Dr. Shimabukuro said at the meeting.

Patients with the rare but serious disorder develop both blood clots, often in the brain, and low levels of platelets, blood components that promote clotting. The disorder is a “rare, clinically serious and potentially life-threatening condition,” Dr. Shimabukuro said.

Last month, after reports first emerged that six women who had received the vaccine had developed the disorder, federal health officials recommended pausing use of the vaccine while they investigated. They lifted the suspension 10 days later and added a warning about the potential risks to the vaccine’s label, which notes that a connection between the vaccine and the condition is “plausible.”

Twenty-two of the confirmed cases so far have been in women, and six have been in men. All were in adults between the ages of 18 and 59 who received the vaccine before the national pause. (There was also one additional case recorded in a 25-year-old man who participated in the clinical trial.)

Three people have died and four remain hospitalized, including one who is in intensive care. No new deaths have been documented since last month’s meeting, Dr. Shimabukuro said.

The overall risk remains exceedingly low. More than 9 million doses of the Johnson & Johnson vaccine have now been administered in the United States.

There have been 12.4 cases per million doses among women between the ages of 30-39 and 9.4 cases per million doses among women between 40 and 49, the two demographic groups that appear to be at highest risk. Among older women and men of all ages, there were fewer than 3 cases per million doses.

Among the 28 confirmed cases, 12 people who developed the disorder had obesity, 7 had high blood pressure, 3 had diabetes, and 3 were taking estrogen, though it is not yet clear whether any of those factors might substantially increase the risk of the disorder.

Officials will continue to monitor for cases of the clotting disorder in people who have been vaccinated, Dr. Shimabukuro said.

There have been no confirmed cases of the clotting disorder following the Pfizer-BioNTech or Moderna vaccines, which employ a different technology, Dr. Shimabukuro said.

As hospitals in Nepal strain to cope with one of the world’s fastest-growing coronavirus outbreaks, relief groups in the Himalayan nation are asking mountain climbers to hand over their used oxygen cylinders so that they can be refilled for Covid-19 patients.

The unusual appeal reflects the strange duality in Nepal: While hundreds of foreign climbers are attempting costly expeditions to the summits of Mount Everest and other peaks, the impoverished nation down below is facing urgent shortages of hospital beds, medical oxygen, coronavirus test kits and other supplies.

Expedition operators are preparing to airlift thousands of cylinders from the Himalayas as expeditions are completed this month, the culmination of the climbing season. Kul Bahadur Gurung, general secretary of the Nepal Mountaineering Association, estimated that tour companies would be able to provide at least 4,000 cylinders by the first week of June.

“We are asking them not to leave even a single oxygen cylinder in the mountains,” Mr. Gurung said.

Climbers attempting to reach the top of Everest, the world’s tallest peak, and other mountains carry oxygen to help them breathe in the thin air. Although Nepal prohibits leaving equipment behind in the mountains, canisters are sometimes left buried in the snow by exhausted climbers or stashed by expedition companies for later use.

Cylinders used in mountaineering are smaller to those typically found in intensive-care wards, but Mahabir Pun, a prominent Nepali scientist who is helping to lead the cylinder drive, said that they could be used by patients who cannot find a hospital bed or who are being treated at home.

“I.C.U. beds are already filled with critical Covid patients, so we want to distribute these portable expedition cylinders with regulators for those patients staying in home isolation,” Mr. Pun said.

Nepal’s outbreak has surged in recent weeks, most likely fueled by the virus’s catastrophic surge in India, with which it shares a long, porous border. On May 1, Nepal reported 26 deaths from the virus. On Tuesday, the official death toll was 225.

Doctors say that a shortage of medical oxygen is a factor in many of the deaths. Many hospitals have stopped admitting new Covid-19 patients, citing a lack of oxygen. Wealthy families are airlifting their loved ones by chartered helicopter to cities where they can find intensive-care beds. Other patients are being treated in makeshift emergency facilities set up in parking lots and other open spaces.

With almost half of Nepal’s coronavirus tests coming back positive, health experts warn that the worst is yet to come.

China has pledged to provide Nepal with 20,000 oxygen cylinders and 100 ventilators, the first batch of which arrived on Tuesday.

Expedition companies are stepping in with smaller donations. Mr. Gurung’s group said that he was sending five dozen cylinders, along with a few more from a local mountaineering museum, to hospitals treating coronavirus patients.

Mingma Sherpa, chairman of Seven Summit Treks, Nepal’s largest expeditions operator, said that he planned to ship as many as 500 cylinders used in expeditions to Everest and other peaks soon after climbers descended to base camps.

“My only condition is that those cylinders should be used for poor and helpless people rather than V.I.P.s,” he said, adding: “It’s our responsibility to help the government during these trying times. We will do it happily.”

A virus variant that has been spreading rapidly in India and designated a variant of concern by the World Health Organization might be more contagious than most versions of the coronavirus, the agency said in a report it published on Tuesday evening.

The W.H.O. emphasized in its report that it wasn’t yet clear how much the variant, known as B.1.617, had contributed to the devastating surge that has crushed India in recent weeks. It cautioned that India, like many countries, is only sequencing a tiny fraction of positive samples, and that with so little surveillance, it’s difficult to make firm conclusions about B.1.617.

The W.H.O. study comes amid growing condemnation of the Indian government’s response to its ferocious virus wave and calls for nationwide restrictions to try to limit the death toll, as hospitals are overrun and crematories burn nonstop.

India recorded more than 360,000 new cases on Wednesday and more than 4,200 deaths, the country’s highest daily death toll since the pandemic began. India has now reported more than 250,000 deaths from the virus, although experts believe that the true toll is far higher.

Experts also caution that it is not yet clear just how much of a factor B.1.617 has played in the explosion of cases in India. They point to a perfect storm of public health blunders, such as permitting enormous political rallies and religious festivals in recent months. It’s possible that the variant is being lifted up by the surge, rather than the other way around.

The W.H.O. speculated that another variant known as B.1.1.7, first identified in Britain and now dominant in the United States, might also be driving the swell in cases.

It’s not yet clear whether B.1.617 causes more severe Covid-19. Anecdotally, doctors in India are reporting higher numbers of young people and children testing positive for the virus and more patients with severe disease requiring oxygen support. But until more genetic sequencing is done, it’s impossible to know if the variant is to blame.

Stacia Wyman, a genomics scientist at the University of California, Berkeley, said that the W.H.O. had made the right decision. She pointed to the fact that the variant had already spread to at least 49 countries. “This appears to be posing the biggest threat right now in terms of transmissibility, with many countries reporting increasing trajectories of the B.1.617 variant,” she said.

B.1.617 is the fourth variant of concern recognized by the W.H.O. The others include B.1.1.7; B.1.351, which swept through South Africa; and P.1, which has devastated Brazil.

B.1.617 first came to light in October 2020. It had a number of mutations, some of which have been proved worrisome in other variants. Preliminary studies on the mutations suggest that some of them might give the coronavirus a tighter grip on cells, increasing their chances of a successful infection.

Other mutations could make it more difficult for antibodies produced by infections with other variants to stick to them. Studies on antibodies produced by vaccinated people also suggest that they work less successfully against B.1.617. Experts expect that most vaccines will remain effective against the variant.

W.H.O. researchers determined that B.1.617 is spreading fast in India, making up over 28 percent of samples from positive tests. The shift suggests that B.1.617 has a higher growth rate than other variants circulating in India, with the possible exception of B.1.1.7. And B.1.617 has been growing rapidly in Britain.

Gagandeep Kang, a pre-eminent Indian virologist, said there was not enough data to conclude whether either variant was contributing to India’s deadlier second wave.

“There is some conflicting data regarding the B.1.1.7 variant, which seems to indicate in some studies that it does cause more severe disease, in other studies not,” said Dr. Kang, the executive director of the Translational Health Science and Technology Institute in India.

Based on reports from hospitals, Dr. Kang said, it appeared that B.1.617 was causing more severe disease but that, again, there was insufficient data to draw conclusions. She said that real-time genetic information would be needed to determine whether B.1.617-infected people needed more oxygen.

Officials in India are trying to track how many fully vaccinated people have fallen ill. If an unusual number of these so-called breakthroughs are caused by a variant such as B.1.617, then that could point to the variant’s ability to evade a vaccine.

India Coronavirus Map and Case Count

See the latest charts and maps of coronavirus cases, deaths and vaccinations in India.

Epidemiologists in the United States are starting to hug again, running errands, gathering outdoors with friends and getting haircuts.

In a new informal survey this month by The New York Times, 723 epidemiologists responded to questions about how they were navigating this in-between phase of the pandemic, when vaccines have become widespread and cases are declining but herd immunity is not assured and Covid-19 remains a threat.

More than at any time in the past year, most are feeling hopeful that Covid-19 will eventually become just another risk in daily life, but not one that paralyzes us.

Nevertheless, their advice was to hold on to most precautions just a bit longer.

“There is a strong likelihood that we will experience unexpected problems due to moving about as if the Covid pandemic was no longer a threat,” said Jana Mossey, an epidemiologist who retired from Drexel University.

“It is not ‘one size fits all,’” said Alicia Riley, a sociologist and epidemiologist at the University of California, San Francisco, expressing a version of the profession’s unofficial motto: It depends. “How safe it is depends on the local levels of community transmission.”

HAVANA — Cuba began a mass vaccination campaign on Wednesday in the capital, Havana, where authorities aim to eventually vaccinate 1.7 million people. The campaign is using homegrown vaccines that have not yet been shown to work, an emergency step intended to blunt the rapid spread of the coronavirus.

The country’s decision to deploy unproven vaccines mirrors the early introduction of vaccines in Russia, China and India, where regulators permitted mass vaccination campaigns to begin before the completion of Phase 3 clinical trials, which assess the vaccines’ effectiveness and safety.

In Florida, news reports critical of the Cuban government accused it of jumping the gun and endangering public health. American and European health regulators do not allow vaccines to be introduced, even for emergency use, until Phase 3 clinical trials are completed.

Though Cuba’s daily coronavirus case counts remain low by Latin American standards, they have spiked alarmingly in recent months. The island, which reported 12,225 confirmed cases in all of 2020, saw 31,465 confirmed cases in April 2021 alone.

The rapid spread of a virus variant first detected in South Africa has contributed to a surge in cases in Cuba, and justifies the early large-scale use of the Sovereign 2 and Abdala vaccines, according to the country’s health minister, Dr. José Angel Portal.

“Confirmed cases are forecast to rise,” he said. “Our regulatory agency and health experts consider that this intervention’s benefits outweigh the risks.”

Scientists rely on Phase 3 trials, in which a vaccine is compared with a placebo, to determine whether vaccines work. Cuba intends to finish the trials for the two vaccines by June.

Cuban scientists argue that with more than 145,000 Cubans already vaccinated as part of clinical trials and an “intervention study” with health workers, they already have enough data to know that serious adverse reactions to the vaccines are rare.

Unlike the American and European vaccines, which were developed in novel ways, “the technological platform the Cuban vaccines are based on has been used for 30 years,” said Dr. Gerardo Guillén, who has led the development of the Abdala vaccine. He said Cuba’s vaccines “are known to be very safe,” and that the proven track record of the technology “factored into the decision.”

Cuba hopes to produce enough doses for its whole population by August. But scientists say that U.S. diplomatic and economic sanctions are slowing down production, making it hard for Cuba to do business with foreign suppliers and complicating international humanitarian initiatives to donate syringes to the island, which needs about 20 million more to vaccinate the whole country.

Of the 90 coronavirus vaccines around the world currently in clinical trials, five were developed in Cuba, the smallest country to develop and produce its own vaccines.

“We will probably be the first country to immunize its whole population with its own vaccine,” said Dr. Eduardo Martínez, president of BioCubaFarma, the state conglomerate overseeing vaccine development and production.

Seychelles, whose population has the highest rate of vaccination against Covid-19 in the world, has had a surge in coronavirus cases. Much of its population has been inoculated with a vaccine made by Sinopharm in China.

The country, a cluster of islands in the Indian Ocean northeast of Madagascar, with a population of just over 100,000, has reimposed a lockdown after having more than 60 percent of its population vaccinated.

More than one-third of the country’s new cases are in people who have been fully vaccinated, according to the Health Ministry. It did not break down how many of them had received the Sinopharm shot and how many had received the other vaccine in use in the country, made by AstraZeneca. About 57 percent of fully vaccinated people in Seychelles got the Sinopharm shot.

China expected the Sinopharm vaccine to be the linchpin of its vaccine diplomacy program — an easily transported dose that would protect much of the developing world.

For the 56 countries counting on the Sinopharm shot to help them halt the pandemic, the news of the surge in Seychelles is a setback that suggests that the vaccine may be significantly less effective in widespread use than they hoped.

• The European Union’s executive branch, the European Commission, recommended on Wednesday that the bloc’s 27 member states limit travel from India to reduce the spread of the B.1.617.2 coronavirus variant that is dominant there, after the World Health Organization described it as a “variant of concern.” The European Commission said member nations should continue to allow very limited travel from India to the bloc for essential reasons, such as family reunification, repatriation of E.U. nationals and their family members, or people seeking humanitarian assistance, but to submit those travelers to strict testing and quarantine protocols. E.U. member states have some leeway on who they allow into their territories, but the commission has played an important role in coordinating these policies throughout the pandemic.

Dr. Patrick Soon-Shiong, the billionaire biotechnology entrepreneur who owns The Los Angeles Times, announced on Wednesday that his corporation and his philanthropic foundation would commit an initial 3 billion South African rand (about $210 million) to transfer the latest technology for producing vaccines and biological therapies to South Africa, where he was born.

Companies there, he said, could then use them to make a second generation of vaccines to address variants of the coronavirus that might make current vaccines less effective.

Dr. Soon-Shiong spoke at an international meeting on the equitable distribution of coronavirus vaccines, diagnostics and therapeutics that was co-chaired by the director-general of the World Health Organization.

Transferring the technology is as important as waiving intellectual property rights, Dr. Soon-Shiong said. “Our goal and our commitment is to come back to South Africa and transfer this kind of technology,” he said.

Referring to South Africa, he said, “Not only do we have the science, we have the human capital and the capacity and the desire.”

Dr. Soon-Shiong said he hoped that the technology, including therapies and vaccines built on viral vectors, messenger RNA and adjuvants, would be used not only to meet the immediate coronavirus crisis, but also to address neglected diseases including schistosomiasis, a parasitic infection common in sub-Saharan Africa.

South Africa, which has had the most confirmed coronavirus cases on the continent, has two manufacturers, Biovac and Aspen Pharmacare, that are involved in producing coronavirus vaccines.

Earlier this year, Biovac announced a partnership with Dr. Soon-Shiong’s company ImmunityBio to help produce an experimental coronavirus vaccine based on an adenovirus vector. The vaccine is in clinical trials in the United States and South Africa.

The Food and Drug Administration on Wednesday authorized a monoclonal antibody drug developed by GlaxoSmithKline and Vir as the third treatment of its kind cleared to help keep high-risk Covid patients out of the hospital.

In laboratory tests the newly authorized drug, known as sotrovimab, has been able to neutralize the virus variants first identified in Britain, South Africa, Brazil, California, New York and India. The U.S. federal government, which has so far purchased the other antibody treatments given to Covid patients in the country, has not announced any plans to purchase the new drug.

GSK has been in conversations with the U.S. government and is “working through existing commercial channels to make sotrovimab available to patients and health systems in need,” Kathleen Quinn, a company spokeswoman, said.

The company said in a news release that it expected the drug to become available in the U.S. “in the coming weeks.”

The new treatment may offer an advantage as concerns rise about new virus variants that may evade some antibody drugs.

The federal government has paused shipments of one antibody treatment on the market, a cocktail of two drugs from Eli Lilly, to eight states because of the high prevalence there of the variants first seen in South Africa and Brazil. Lab experiments suggest that those variants can resist Lilly’s treatment. (The other available antibody treatment, a cocktail of two drugs from Regeneron, appears to neutralize the array of variants, based on lab tests.)

GSK and Vir’s treatment is a single drug, designed to mimic the antibodies generated naturally when the immune system fights off the coronavirus, like those detectable after someone infected with it recovers. Its authorization was based on a study of 583 volunteers who had started experiencing symptoms within the previous five days. The study found that those who got the GSK-Vir treatment showed an 85 percent reduction in their risk of hospitalization or death, compared with those who got a placebo.

Even as vaccination numbers rise and infection rates fall in the United States, the antibody treatments are likely to remain an important tool for preventing bad outcomes in high-risk patients, doctors say. Thousands of people in the United States are still testing positive, and hundreds dying, each day.

Last week the F.D.A. broadened the criteria that doctors can use to determine eligibility for the treatment, opening the door for more young people with certain medical conditions like hypertension and members of racial or ethnic groups considered to be at higher risk than others for bad medical outcomes.

“Ultimately, it gives prescribers a lot of latitude in what they can give this for,” said Dr. Walid F. Gellad, who directs the Center for Pharmaceutical Policy and Prescribing at the University of Pittsburgh.

But the drugs from Lilly and Regeneron have not been used as widely as expected for a range of reasons, according to public health experts.

The antibody drugs are all cumbersome to administer. Patients often don’t know to ask for them or where to find them. And many doctors were skeptical of the evidence supporting the treatments when they first became available last November, though that has changed as more clinical trials have reported impressive results.

“There’s still a role for these,” Dr. Gellad said. “The problem is just people aren’t getting them who could benefit from them, and having another one on the market doesn’t necessarily solve that.”

GSK and Vir’s treatment, like the other antibody drugs, must be administered via intravenous infusion by a health care provider, which will make it harder to access. The drug makers are testing a formulation injected intramuscularly, like a vaccine, but that is not expected to be available soon.