AstraZeneca’s Covid-19 vaccine being administered in Milan on Monday.
Alessandro Grassani for The New York Times

Federal health officials said early Tuesday that results from a U.S. trial of AstraZeneca’s Covid-19 vaccine may have relied on “outdated information” that “may have provided an incomplete view of the efficacy data,” casting doubt on an announcement on Monday that had been seen as good news for the company as well as the global vaccination drive.

In a highly unusual statement released after midnight, the National Institute of Allergy and Infectious Diseases said that the data and safety monitoring board, an independent panel of medical experts under the National Institutes of Health that has been helping to oversee AstraZeneca’s U.S. trial, had notified government agencies and AstraZeneca late Monday that it was “concerned” by information the drugmaker had released that morning.

The institute urged AstraZeneca to work with the monitoring board “to review the efficacy data and ensure the most accurate, up-to-date efficacy data be made public as quickly as possible.”

In a news release on Monday announcing the results of the U.S. trial, AstraZeneca said that the vaccine it developed with the University of Oxford was 79 percent effective against Covid-19, higher than observed in previous trials, and completely prevented the worst outcomes from the disease. The long-anticipated results were seen as encouraging global confidence in the vaccine, which was shaken this month when more than a dozen countries, mostly in Europe, temporarily suspended the shot’s use over concerns about possible rare side effects.

In recent days, the monitoring board’s analysis was delayed several times because the board had to ask AstraZeneca for revised reports from those handling trial data on behalf of the company, according to a person familiar with the matter who was not authorized to discuss it publicly.

The monitoring board ultimately conveyed the results of the study to AstraZeneca in a meeting over the weekend, leading to the company’s announcement Monday morning.

Asked about the issues with data submission to the monitoring board, an AstraZeneca spokeswoman, whom AstraZeneca declined to name, said Friday that it was “completely incorrect” that the trial data had formatting problems or had not been submitted to the study monitor in a clean fashion.

“As is often the case,” the spokeswoman said, monitoring boards “can request new or clarifying analyses of data from the trial. This would enable them to ensure the robustness of their determinations.”

AstraZeneca did not immediately return a request for comment early Tuesday.

Dr. Eric Topol, a clinical trials expert at Scripps Research in San Diego, said it was “highly irregular” to see such a public display of friction between a monitoring board and a study sponsor, which are typically in close concordance.

“I’ve never seen anything like this,” he said in an interview after the institute’s statement was released. “It’s so, so troubling.”

AstraZeneca’s U.S. trial, which involved more than 32,000 participants, was the largest test of its kind for the shot. Although no clinical trial is large enough to rule out extremely rare side effects, AstraZeneca reported that its study turned up no serious safety issues.

The fresh data may have arrived too late to make much difference in the United States, where the vaccine is not yet authorized and is unlikely to become available before May. By then, federal officials predict, there will be enough vaccine doses for all of the nation’s adults from the three vaccines that have already been authorized: Pfizer-BioNTech, Moderna and Johnson & Johnson.

Even so, the better-than-expected results were seen as a heartening turn for AstraZeneca’s shot, whose low cost and simple storage requirements have made it a vital piece of the drive to vaccinate the world.

The results were also thought to ease concerns about the AstraZeneca vaccine in Europe. In an effort to increase public confidence, many European political leaders have gotten the injections in recent days.

Regulators in Europe initiated a safety review of AstraZeneca’s vaccine earlier this month after a small number of people who had recently been inoculated developed blood clots and abnormal bleeding. The trial did not turn up any sign of such problems, although some safety issues can only be detected in the real world, once a drug or vaccine has been given to millions of people.

AstraZeneca said on Monday that it would continue to analyze the new data and prepare to apply in the coming weeks for emergency authorization from the Food and Drug Administration. The vaccine has already been approved in more than 70 countries, but clearance from American regulators would bolster its global reputation.

Munich last week. The number of coronavirus cases in Germany is rising, prompting the government to extend lockdown measures.
Laetitia Vancon for The New York Times

Chancellor Angela Merkel of Germany and state governors have agreed to extend lockdown measures, asking Germans to stay home for five days during the Easter holiday, in an effort to tame a spike in coronavirus cases.

The extension will last until April 18, according to the Reuters news agency, which cited the chancellor’s statement after an overnight meeting with the heads of Germany’s 16 states. Holy Week begins on Sunday.

Germany is the latest nation in Europe to tighten restrictions as more contagious virus variants spread and the continent struggles to vaccinate its citizens quickly enough. Poland, Italy and parts of France have ordered that residents stay home, and many businesses have shut ahead of the holiday.

A resurgent virus and lagging vaccinations have forced governments to renege on promises that they would slowly reopen businesses and society as spring approached. That has spurred protests across Europe as people chafe at more restrictions.

Europe’s vaccine campaign slowed after a small number of cases of blood clots and abnormal bleeding were reported in patients who received the AstraZeneca vaccine, dampening confidence in its safety. While the European drug regulator, the European Medicines Agency, cleared the vaccine for use last week and said it was “safe and effective,” the scare further complicated the vaccination efforts.

Just three weeks ago, Ms. Merkel and state officials hammered out a road map to reopening that relied on a decline in case rates. Two weeks and a 57 percent increase in daily new cases later, it is clear that Germany is headed into another virus wave.

The number of cases in Germany has more than doubled to about 13,000 per day from 6,000 in mid-February, according to a New York Times database. The country has been reopening as the more infectious B.1.1.7 variant that was first found in Britain spreads rapidly, making up nearly three-quarters of new cases, German scientists say.

A vaccination site in Brooklyn earlier this month.
Brittainy Newman for The New York Times

West Virginia on Monday became the third state to open Covid-19 vaccination to all adults and New York expanded eligibility as state governments try to meet President Biden’s request to open access to all adults by May 1.

West Virginia joined Alaska and Mississippi on Monday in making everyone older than 16 eligible, while Gov. Andrew M. Cuomo of New York said residents older than 50 could sign up for a shot starting on Tuesday.

Tennessee announced that all residents 16 and older would be eligible for vaccination starting April 5, joining a growing list of states that have announced plans to meet or beat Mr. Biden’s goal of May 1.

“Tennessee will beat that deadline,” Gov. Bill Lee said on Monday. He also said that all residents 55 and older as well as those who work in critical infrastructure industries could make vaccine appointments immediately.

The governor of West Virginia, Jim Justice, said the state’s senior population would continue to be prioritized for vaccines, but he encouraged all residents 16 years and older to get in line. The state has had a successful vaccination program from the start, and as of Sunday, at least 26 percent of the total population had received at least one shot, according to a New York Times analysis of data from the Centers for Disease Control and Prevention.

Nationally, about 25 percent of the U.S. population has received at least one shot, and the pace of vaccinations has been steadily increasing: An average of about 2.49 million shots are given daily, compared with under one million two months ago.

Mr. Cuomo has not set a timeline for broadening vaccine eligibility to all adults, but New York has been gradually expanding as more vaccine supply has become available. As of Sunday, 26 percent of New York State’s total population had received at least one shot of a vaccine, while 13 percent had been fully vaccinated, according to a New York Times database.

The state currently allows everyone 60 or older to get vaccinated, as well as a number of essential workers and people with certain health conditions that make them more susceptible to serious illness from the virus.

Last week, New York also began to allow public-facing government employees, nonprofit workers and essential building service workers to receive inoculations.

On Sunday, Mr. Cuomo announced that pharmacies would be able to vaccinate adults with certain underlying health conditions; they were previously limited to inoculating older adults and teachers.

Other states have also broadened eligibility at specific vaccination sites. Arizona announced on Monday that beginning Wednesday, all residents 16 and older could get vaccinated at state-operated locations in Maricopa, Pima and Yuma counties.

A coronavirus testing center in Los Angeles last week.
Valerie Macon/Agence France-Presse — Getty Images

Dr. Rochelle Walensky, the director of the Centers for Disease Control and Prevention, again warned Americans on Monday about the spread of the coronavirus, saying that with increased travel, looser pandemic restrictions and worrisome variants bearing down on the United States, another surge could erupt if Americans did not take protection efforts seriously “for just a little bit longer.”

Virus variants are making up a bigger share of cases, she said at a White House briefing. A variant first discovered in California that now accounts for over half of the state’s cases is spreading in Nevada and Arizona. A fast-spreading variant first detected in Britain is now responsible for 9 percent of cases in New Jersey and 8 percent of cases in Florida, she said.

“We are at a critical point in this pandemic, a fork in the road, where we as a country must decide which path we are going to take. We must act now,” said Dr. Walensky, who has been one of many federal officials in recent weeks to warn governors against lifting mask mandates too soon. “And I am worried that if we don’t take the right actions now, we will have another avoidable surge, just as we are seeing in Europe right now and just as we are so aggressively scaling up vaccination.”

The C.D.C.’s efforts to track down the variants have substantially improved in recent weeks and will continue to grow, in large part because of $1.75 billion in funds for genomic sequencing in the stimulus package that President Biden signed into law this month. Dr. Walensky told lawmakers last week that between 10,000 and 14,000 test samples were being sequenced each week to locate variants, and that the C.D.C. was aiming for about 25,000. By contrast, Britain began a highly touted sequencing program last year.

On Monday, Dr. Walensky also cautioned that the Northeast and upper part of the Midwest were again seeing a troublesome rise in cases. If states continue to relax their pandemic restrictions while cases are still high, she said, progress could be halted.

“We’re reaching out to individual states, trying to encourage them,” she said. “We are having weekly governors’ calls. We’re doing outreach with states, territories to encourage them to look at their case data, to look at what’s happening with the variants, and to do as much outreach as we can to try and — to slow down the relaxation.”

Sunday was the busiest day for air travel in the United States so far this year, according to the Transportation Security Administration. More than 1.5 million people passed through T.S.A. checkpoints on Sunday, nearly a million more than the same day last year.

Dr. Walensky said that air travel — much of it for spring break trips — also threatened to increase cases around the country, and that Americans should avoid it.

“We’re worried not just for what happens when you are on the airplane itself, but what happens when people travel,” she said. “We just don’t want to be at this rapid uptick of cases again, and that is very possible that that could happen. We’ve seen that. We’re behind the eight ball when that starts to happen. And that results in uptick of cases, hospitalizations and then death.”

Still, there have been signs of progress. The country is averaging more than 54,000 new cases a day, according to a New York Times database, a level comparable to mid-October. Daily death reports, which stayed stubbornly high long after the post-holiday surge, have finally come down sharply, to levels not seen since mid-November. Hospital admissions are stable, Dr. Walensky said on Monday. And the pace of vaccinations continues to increase, with providers administering an average of about 2.49 million doses per day as of Sunday.

The C.D.C. said on Sunday that about 82.8 million people had received at least one dose of a Covid-19 vaccine, including about 44.9 million people who had been fully vaccinated by Johnson & Johnson’s single-dose vaccine or the two-dose series made by Pfizer-BioNTech or Moderna.

The White House announced on Monday another federally run vaccination site, which will open in Washington State and be able to administer up to 1,200 shots per day.

Bryan Pietsch and Melina Delkic contributed reporting.

Vials being inspected at the Regeneron’s facilities in New York state, for efforts on an experimental coronavirus antibody drug.
Regeneron, via Associated Press

A monoclonal antibody treatment developed by the drug maker Regeneron sharply cut the risk of hospitalization and death when given to high-risk Covid-19 patients in a large clinical trial, the company announced on Tuesday.

The results are the latest in a flurry of growing evidence that the infused drugs, meant to mimic the antibodies that the immune system generates naturally in fighting the coronavirus, can help infected patients avoid the worst outcomes if given early.

Regeneron’s treatment, a cocktail of two antibody drugs, was given to former President Donald J. Trump shortly after he got sick with Covid-19 last fall and is now one of three such therapies available in the United States.

The new results come from a Phase 3 trial that enrolled more than 4,500 patients beginning in late September, around the time virus cases began to climb dangerously in the United States. The study found that patients who got the infused treatment within 10 days of developing symptoms or testing positive had a roughly 70 percent reduced risk of being hospitalized or dying compared to patients who were infused with a placebo.

“I think these are exciting data,” said Dr. Rajesh Gandhi, an infectious diseases physician at Massachusetts General Hospital who was not involved in the study.

Even as vaccinations speed up, antibody treatments are expected to be helpful for high-risk people who still get sick for many months at least, and longer still if the virus can’t be wiped out. While there are signs that emerging virus variants may in some cases make antibodies less potent, Regeneron’s cocktail has not shown such vulnerability in laboratory tests.

In the new findings, Regeneron’s treatment worked equally well when given at half the dosing at which it was authorized. Regeneron said that it planned to request that the Food and Drug Administration allow the treatment to be given at that reduced strength.

Such a change would bring several advantages: While the cocktail is safe, getting it at a lower dose reduces the odds of side effects, such as an infusion reaction.

It would also allow Regeneron to boost the supply it can provide the United States. The company said that it had expected to supply the country with about 750,000 doses at the originally authorized higher strength. If the lower strength is authorized, the company expects to provide about 1.25 million doses.

The antibody treatments from Regeneron and the drug maker Eli Lilly, which makes the other two such drugs authorized in the United States, were expected to be in high demand and to serve as a bridge in fighting the pandemic before vaccinations ramped up. Instead, they ended up sitting on refrigerator shelves in many places even during recent surges.

Many patients and their doctors did not know to ask for them or where to find them. Overwhelmed hospitals lacked the bandwidth to prioritize giving out the treatments. And some doctors were unconvinced by the relatively weak evidence available last fall supporting their use.

That picture is gradually shifting, thanks to improved logistics and more awareness. And more solid evidence, like the new data from Regeneron, also appears to be helping the drugs get used more widely. “As the data get stronger and stronger, I would expect that use will increase and increase,” Dr. Gandhi said.

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Mayor Bill de Blasio on Monday said that all New York City students in the public school system, who’ve been learning remotely this year, would have another opportunity to sign up for in-person learning between March 24 and April 7.Anna Watts for The New York Times

New York City parents whose children have been learning remotely this year in the city’s public schools system will have another opportunity to sign up for in-person learning, starting this Wednesday until April 7, Mayor Bill de Blasio said Monday.

While all parents can indicate interest, the city only has plans for now to bring more elementary school students into school buildings in April. Mr. de Blasio said last week that younger grades will switch from six feet of distancing in classrooms to three feet, a change prompted by recent guidance from the Centers for Disease Control and Prevention on social distancing in schools. The city has not yet determined whether it will shift the distancing rules for middle and high school students.

New York City high schools also opened for in-person classes on Monday for the first time since November. The mayor said that about half of high schools will be able to offer full-time instruction for students. But some parents have expressed frustration that their children are returning to high school classrooms where they will log onto remote school along with their peers learning from home, rather than getting typical classroom instruction.

Mr. de Blasio announced Monday that over 800 city schools have lost enrollment during the pandemic but will not lose funding as a result. Federal stimulus money has allowed the city to return roughly $130 million to schools that saw budget cuts earlier this school year, the mayor said.

GLOBAL ROUNDUP

A crowded market in Mumbai, India, on Friday. The surrounding state of Maharashtra is at the center of a new coronavirus outbreak.
Francis Mascarenhas/Reuters

The coronavirus, once seemingly in retreat in India, is again rippling across the country. On Monday, the government reported almost 47,000 new cases, the highest number in more than four months. It also reported 212 new deaths from the virus, the most since early January.

The outbreak is centered in the state of Maharashtra, home to Mumbai, the country’s financial hub. Entire districts of the state have gone back into lockdown. Scientists are investigating whether a new strain found there is more virulent, like variants found in Britain, South Africa and Brazil.

Officials are under pressure to aggressively ramp up testing and vaccination, especially in Mumbai, to avoid disruptions like the dramatic nationwide lockdown last year, which resulted in a recession.

But less than 3 percent of India’s population of 1.3 billion has received a jab, including about half of health care workers.

The campaign has also been plagued by public skepticism. The government approved a domestically developed vaccine, called Covaxin, before its safety and efficacy trials were even over, though preliminary findings since then have suggested it works.

The other jab available in India is the Oxford-AstraZeneca vaccine, which was suspended in some countries after a number of patients reported blood clots and strokes, though most have since reversed course and scientists haven’t found a link between the shots and the patients’ conditions.

In other developments around the world:

  • Taiwan, one of the few places in the world to successfully contain the coronavirus from the beginning of the pandemic, kicked off its vaccination drive on Monday. Premier Su Tseng-chang and Chen Shih-chung, the health minister, were among the first to be inoculated with the AstraZeneca vaccine, the only one authorized so far. The vaccinations were widely televised in Taiwan, part of an effort to increase confidence in the vaccine. Taiwan has been relatively slow to start inoculating, in part because it has had so few reported cases: As of Monday, the all-time total was 1,006, with 10 deaths, on an island of 24 million people.

  • The Chinese company CanSino Biologics said on Monday that Hungary had authorized its Covid-19 vaccine for emergency use, the first European country to do so. The vaccine, known as Convidecia, is a single-dose product developed with the Chinese military. Hungary is also using another Chinese-made vaccine, from Sinovac, and Russia’s Sputnik V, as well as the Western ones approved elsewhere in the European Union.

  • France’s labor minister, Élisabeth Borne, has been hospitalized with Covid-19, the authorities announced on Monday, a first for a top French official. “Her health is improving,” according to a statement from her ministry. President Emmanuel Macron had the virus in December, and several other ministers have announced positive test results, including the culture minister two days ago.

  • Health officials in South Africa sold unused doses of the AstraZeneca vaccine to 14 other states in the African Union, Reuters reported on Sunday. It paused the use of the vaccine last month after a small trial showed it offered only minimal protection against mild to moderate illness caused by the dominant local variant of the virus.

  • With cases rising sharply in Germany, Chancellor Angela Merkel and state leaders are expected on Monday to extend the country’s lockdown. The new rules, which are likely to be in effect until at least April 18, would reverse steps toward reopening that the leaders had approved just weeks ago.

  • The distributor of China’s Sinopharm vaccine in the United Arab Emirates says it has started offering a “very small number” of people a third shot after these recipients reported insufficient levels of antibodies following a two-dose regimen.

  • Australia and New Zealand are moving closer to opening a travel bubble, with Prime Minister Jacinda Ardern of New Zealand saying on Monday that she would announce a date for the start of quarantine-free travel on April 6. Both countries have all but eliminated the coronavirus. Though Australia has lifted its quarantine requirement for passengers arriving from New Zealand, New Zealand has yet to reciprocate, despite pressure from opposition parties and the country’s tourism sector.

The Idaho Legislature shut down for two weeks after members of the lower house tested positive for coronavirus.
Keith Ridler/Associated Press

The Idaho State Legislature is in a two-week recess after nearly 10 percent of its House members tested positive for the coronavirus in one week.

The decision wasn’t surprising and was done to “err on the side of caution,’’ the Republican speaker of the House, Scott Bedke, said at a news conference on Friday after the shutdown was announced. Six of the lower house’s 70 lawmakers tested positive for the virus last week.

The recess is a significant step back for a legislature that has opposed taking action on Covid-19 and whose members have expressed skepticism about the danger the virus poses. The average number of new daily cases in Idaho has risen 22 percent in the past two weeks, according to a New York Times database.

Resistance to safety measures has been robust both among many of the state’s politically active Republican residents and among their lawmakers. Some call coronavirus safety measures an assault on their freedoms. Others shrug off the risk.

Representative Ryan Kerby, a Republican from rural New Plymouth, was one of the House members to get sick. Near New Plymouth, a southwest Idaho town just a few miles from the Snake River border with Oregon, “a lot of people get it, have it for a week or two and get over it and move on,” he said on Monday.

“We were going to take two weeks off anyway because money is coming from the feds and we need to study it,” he said referring to the money allotted to the state in the coronavirus relief bill that President Biden signed last week.

Most of the Republicans who dominate both chambers refuse to wear masks while in the State Capitol. Legislative leaders have declined to issue mask or social-distancing orders, although air purifiers have been installed in the state house and witnesses have been allowed to testify remotely at committee meetings.

Two Democratic representatives with compromised immune systems sued Mr. Bedke last year, demanding measures to protect lawmakers from infection, after protesters opposing coronavirus restrictions broke through a Capitol door in August.

Republicans have sharply criticized a year-long coronavirus emergency declared by Idaho’s Republican governor, Brad Little, and are considering a bill to blunt his authority to address crises like pandemics.

The attacks have continued. Mr. Little’s lieutenant governor, Janice McGeachin, joined 10 Republican legislators last fall in a video calling the declaration an attack on their freedom, and she was one of more than 100 people who burned masks outside the Capitol early this month to protest restrictions issued under the order.

The sole Democrat among the six House members with new coronavirus cases, Representative James Ruchti, said he believed Mr. Little had managed the pandemic about as deftly as anyone could.

He also suggested that Mr. Little was not alone in his party in seeing the virus as an emergency.

The issue will be on the front burner when the legislators return to the Capitol in early April. Besides the state budget and a proposed tax cut, there are bills that would limit the authority of public health districts, crimp Mr. Little’s emergency authority and, not least, bar state and local government agencies from requiring anyone to wear a mask “for the purpose of preventing or slowing the spread of a contagious disease.”

The bill was among the very last to come up in committee on Friday before the House and Senate were hastily recessed. “The irony is thick,” Mr. Ruchti said.

A young girl waits to be tested for coronavirus in the Kibera slum in Nairobi on October 18, 2020.
Tony Karumba/Agence France-Presse — Getty Images

Three months after rich countries began vaccinating health workers, Kenyans like Stella Githaiga, a nurse, had been infected and left behind: Employed in the country’s largest public hospital, she caught the coronavirus on an outreach trip to remote communities in February, she believes, sidelining her even as Kenya struggles with a vicious third surge of infections.

Ms. Githaiga and her colleagues are victims of one of the most galling inequities in a pandemic that has exposed so many: Across the global south, health workers are being sickened and killed by a virus from which doctors and nurses in many rich countries are now largely protected.

That is just the most visible cost of a rich-poor divide that has deepened in the second year of the pandemic. Of the vaccine doses given globally, roughly three-quarters have gone to only 10 countries. At least 30 countries have not yet injected a single person.

Scientists have long warned that such unfair treatment could not only haunt poorer countries, but also rich ones, if the continued spread of the virus allows it to mutate in ways that undermine vaccines. But the greatest human costs will almost surely be borne by less wealthy nations.

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Vice President Kamala Harris traveled to Jacksonville on Monday to visit a coronavirus vaccination center amid Florida’s fears of another virus surge.Michelle V. Agins/The New York Times

Vice President Kamala Harris traveled on Monday to Jacksonville, Fla., to tour a vaccination center and host an event at a food pantry, two stops designed to promote the Biden administration’s pandemic stimulus package to Americans in a state where officials are fearing another coronavirus surge.

Amid tensions over how best to contain the virus in Florida, Ms. Harris toured one of the federally supported vaccination centers, the Gateway Town Center shopping complex, that have administered tens of thousands of shots in recent days.

Answering questions from reporters traveling with her, Ms. Harris did not offer any specifics from the administration on how local officials, who have largely opened the state for business, should get the virus under control.

“I’m here to emphasize the importance of vaccinations and getting the vaccine,” Ms. Harris said. “One thing is for sure, if you get vaccinated when it’s your turn, you are much more likely to avoid contracting Covid.”

Florida has logged more than two million cases of coronavirus since the pandemic began, according to a New York Times database. An influx of spring breakers to South Florida, and Miami Beach in particular, has caused officials to institute mandatory curfews over concerns that the virus will continue to spread.

Later on Monday, Ms. Harris hosted an event at Feeding Northeast Florida, a food pantry, to emphasize one of the $1.9 trillion relief package’s biggest selling points: The plan aims to reduce child poverty through a generous tax credit.

Ms. Harris also fielded questions on whether she would visit the U.S.-Mexico border — “not today,” she replied — and said the Biden administration had been left with “a very challenging situation,” a reference to the zero-tolerance immigration policies under the Trump administration.

“We’ve got to treat this issue in a way that is reflective of our values as Americans, and do it in a way that is fair and is humane,” she said.

Prime Minister Benjamin Netanyahu of Israel takes personal credit for the country’s vaccination campaign, which has fully vaccinated about half the population of nine million.
Menahem Kahana/Agence France-Presse — Getty Images

JERUSALEM — Vaccinated Israelis are working out in gyms and dining in restaurants. They’re partying at nightclubs and cheering at soccer matches by the thousands.

Prime Minister Benjamin Netanyahu is taking credit for bringing Israel “back to life,” as he calls it, and banking on the country’s giddy, post-pandemic mood of liberation to put him over the top in a close election on Tuesday.

But nothing is quite that simple in Israeli politics.

Even as most Israelis appreciate the government’s world-leading vaccination campaign, many worry that the grand social and economic reopening may prove premature and suspect that the timing is political.

Instead of a transparent reopening process led by public health professionals, “decisions are made at the last minute, at night, by the cabinet,” said Hagai Levine, an epidemiologist at the Hebrew University-Hadassah Braun School of Public Health in Jerusalem. “The timing, right before the election, is intended to declare mission accomplished.”

The parliamentary election on Tuesday will be the country’s fourth in two years. Mr. Netanyahu is on trial on corruption charges and analysts say his best chance of avoiding conviction lies in heading a new right-wing government. He has staked everything on his handling of the coronavirus crisis.

He takes personal credit for the country’s inoculation campaign, which has fully vaccinated about half the population of nine million — outpacing the rest of the world — and he has declared victory over the virus.

“Israel is the world champion in vaccinations, the first country in the world to exit from the health corona and the economic corona,” he said at a pre-election conference last week.

The vaccination campaign has been powered by early delivery of several million doses from Pfizer, and Mr. Netanyahu has presented himself as the only candidate who could have pulled off that deal, boasting of his personal appeals to Pfizer’s chief executive, Albert Bourla, who, as a son of Holocaust survivors, has great affinity for Israel.

Mr. Netanyahu even posted a clip from “South Park,” the American animated sitcom, acknowledging Israel’s vaccination supremacy.

But experts said his claim that the virus was in the rearview mirror was overly optimistic.

Scientists say that in addition to altering dietary patterns, pandemic lockdowns have curtailed the physical activity of daily living.
Etienne Laurent/EPA, via Shutterstock

Soon after the pandemic started a year ago, Americans started joking about the dreaded “quarantine 15,” worried they might gain weight while stuck at home with stockpiles of food, glued to computer screens and binge-watching Netflix.

The concern is real, but assessing the problem’s scope has been a challenge. Surveys that simply ask people about their weight are notoriously unreliable, and many medical visits have been virtual.

Now a very small study using objective measures — weight measurements from Bluetooth-connected smart scales — suggests that adults under shelter-in-place orders gained more than half a pound every 10 days.

That translates to nearly two pounds a month, said Dr. Gregory M. Marcus, senior author of the research letter, published on Monday in the peer-reviewed JAMA Network Open. Americans who kept up their lockdown habits could easily have gained 20 pounds over the course of a year, he added.

“We know that weight gain is a public health problem in the U.S. already, so anything making it worse is definitely concerning, and shelter-in-place orders are so ubiquitous that the sheer number of people affected by this makes it extremely relevant,” said Dr. Marcus, a cardiologist and professor of medicine at University of California, San Francisco.

The new study analyzed data obtained from 269 U.S. participants who were involved in an ongoing cardiology study, the Health eHeart Study. They volunteered to report weight measurements from Bluetooth-connected smart scales and weighed themselves regularly; the researchers gathered 7,444 weight measurements over a four-month period, an average of 28 weight measurements from each participant.

The group was not nationally representative, by any means, so the results are not generalizable: About three-quarters were white, and just 3.5 percent identified as Black or African-American; about 3 percent identified as Asian-American. The average age was 51, and they were split almost evenly among men and women.

The lockdowns have certainly had an effect on dietary patterns, on what people eat and how often they eat. But the restrictions also curtailed the humdrum physical activity that is part and parcel of daily living, the researchers said.

“If you think about people commuting, even running to the subway or bus stop, or stepping in at the post office to mail a letter, or stopping at the store — we burn a lot of calories in non-exercise activities of daily living,” said Leanne Redman, a professor of clinical physiology at the Pennington Biomedical Research Center, part of Louisiana State University.

The Metropolitan Museum of Art has cut pay and laid off employees during the pandemic.
Jeenah Moon for The New York Times

It started as a stopgap measure to respond to the pandemic, a temporary two-year loosening of an Association of Art Museum Directors’ policy that has long prohibited American institutions from selling art in their collections to help pay the bills.

But more and more museums are taking advantage of the policy and the association began discussing making it permanent, an idea that, depending on which institution you talk to, either makes perfect sense or undermines the very rationale of their existence.

The debate has grown heated in recent weeks, pitting museum against museum, and forcing the association — which serves as the industry’s referee and moral watchdog — to postpone talks about a decision.

The longstanding policy — enforced by the association and widely embraced by its members — has been that the art owned by institutions was held for the public benefit and, as such, should be mostly retained.

Items could be sold only if they were duplicative or no longer in line with the museum’s mission, and the proceeds were to spent on other art, not used for staff salaries or other operating costs.

But in the financial upheaval of the pandemic, the association temporarily loosened the restrictions last year, allowing museums to sell artwork to help pay for the care of their collections.

The issue came to a head last month when the Metropolitan Museum of Art in New York acknowledged that it might take advantage of this policy shift, including a direction of the proceeds toward the salaries of those involved in collection care.

Museums typically look to the Met — the country’s largest — for guidance and many are troubled by the idea that it would use art sale proceeds to underwrite operating expenses.

Randy and Rochelle Forester, right, with their friends Phyllis and Sheldon Schwartz in Detroit. Ms. Forester celebrated being “out of sweats, to put on some pretty earrings and lipstick and be back in the world a little bit.”
Cydni Elledge for The New York Times

Older people represent the vast majority of Americans who are fully vaccinated against the coronavirus, and they are emerging this spring with the daffodils, tilting their faces to the sunlight outdoors. They are filling restaurants, hugging grandchildren and booking flights.

Marcia Bosseler is back to playing Ping-Pong — and beating all the men, she says — at her apartment complex in Coral Gables, Fla.

Randy and Rochelle Forester went out to eat with another couple for the first time in a year, and Ms. Forester celebrated the pleasure of being “out of sweats, to put on some pretty earrings and lipstick and be back in the world a little bit.” Fully vaccinated, Louis Manus Jr., an 82-year-old Navy veteran in Rapid City, S.D., is getting ready for his first vintage car club meeting in a year.

The upside-down world in which older Americans are drinking more martinis inside restaurants at a far greater rate than millennials will be short-lived. In a few months, all that will most likely be over, and vaccines will be available to all who want them.

For now, about two-thirds of Americans over 65 have started the vaccination process and nearly 38 percent are fully vaccinated, compared with 12 percent of the overall population, giving the rest of the nation a glimpse into the after times.

“I am just enjoying my life,” said Robbie Bell, 75, who recently went out for a birthday celebration in Miami with two friends — one of whom was hospitalized last year with a dangerous case of Covid — and even hit the dance floor.

Many of those fully vaccinated — older and younger — are as cautious as ever, more like those crocuses that bloom in the day only to fold quietly back into their stems at night. Many said that their vigilance stemmed from the spread of some more contagious variants of the virus and from uncertainty over whether those who are vaccinated could still spread it.

“I would say that we are less afraid, but not fear-free,” said John Barkin, 76, who lives with his wife, Chris, 70, in Chestertown, Md. “There are so many stories about mutations, etc., and so many yet-to-be-vaccinated people seem to be acting more and more irresponsibly. Both of us feel that we have invested a year of being careful, so to continue on conservatively seems the way to go.”

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The police fired pepper balls to disperse crowds after an 8 p.m. curfew went into effect on Saturday. Local Miami officials said people had flocked to the city because of its relatively few coronavirus restrictions.Cristobal Herrera-Ulashkevich/EPA, via Shutterstock

One day after the spring break oasis of South Beach descended into chaos, with the police struggling to control overwhelming crowds and making scores of arrests, officials in Miami Beach decided on Sunday to extend an emergency curfew for up to three weeks.

Officials went so far as to approve closing the famed Ocean Drive for four nights a week until April 12, including to pedestrians, during the 8 p.m. to 6 a.m. curfew. Residents, hotel guests and employees of local businesses are exempt.

The strip, frequented by celebrities and tourists alike, was the scene of a much-criticized skirmish on Saturday night in which police officers used pepper balls to disperse a large crowd of sometimes unruly and mostly unmasked revelers just hours after the curfew had been introduced.

The restrictions were a stunning concession to the city’s inability to control unwieldy crowds. The city and the state of Florida have aggressively courted visitors.



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“I believe it’s a lot of pent-up demand from the pandemic and people wanting to get out,” David Richardson, a member of the Miami Beach City Commission, said on Sunday. “And our state has been publicly advertised as being open, so that’s contributing to the issue.”

In an emergency meeting, the commission approved maintaining the curfew in the city’s South Beach entertainment district from Thursday through Sunday for three more weeks, which is when spring break typically ends. Bridges along several causeways that connect Miami Beach with the mainland will also continue to be shut during the curfew.

Law enforcement officials said many people had been drawn to the city for spring break this year because it has relatively few virus restrictions, mirroring the state at large. And hotel rooms and flights have been deeply discounted, to make up for the months of lost time.

Miami-Dade County, which includes Miami Beach, has recently endured one of the nation’s worst outbreaks, and more than 32,000 Floridians have died from the virus, an unthinkable cost that the state’s leaders rarely acknowledge. The state is also thought to have the highest concentration of B.1.1.7, the more contagious and possibly more lethal virus variant first identified in Britain.

President Vladimir V. Putin of Russia said Monday during a videoconference on vaccine production that he would soon be inoculated himself.  
Pool photo by Alexey Druzhinin

President Vladimir V. Putin of Russia said on Monday that he would receive one of Russia’s coronavirus vaccines on Tuesday, ending a lengthy, unexplained delay in getting inoculated.

The announcement came seven months after Russian national regulators approved a domestically developed vaccine for emergency use, an unusually long time for a head of state to wait before setting a public example for people who are hesitant about vaccination.

Russian regulators approved the Sputnik V vaccine in August, before large-scale clinical trials to determine its safety and efficacy were complete; the trials did not wrap up until December. The early approval was criticized by many Western experts as premature and potentially risky. Even so, Russia began limited vaccinations in August.

Under Russia’s vaccination rules, people Mr. Putin’s age (he is 68) became eligible in December. But he was in no hurry, and months passed without any word from the Kremlin of his having been immunized. In February he said he would wait until the autumn and receive the vaccine along with his annual flu shot.

In the meantime, he took extraordinary precautions against infection, holding meetings by video conference rather than in person.

Mr. Putin announced his decision to go ahead and get the shot now during a video conference on Monday with vaccine makers, who assured him that Russia was now on track to produce enough doses for most of the country’s adult population by late summer. Russia has also exported Sputnik V doses to a number of countries and licensed a few to produce their own supplies.

Despite the early start, Russia has fallen far behind most European Union nations and the United States in vaccinating its population. Some 3.9 percent of the Russian population has received at least one dose so far, compared with 25 percent in the United States.

In addition to Sputnik V, Russia has approved for emergency use two more domestically developed vaccines, EpiVacCorona and CoviVac, that have yet to complete their clinical trials.

Mr. Putin’s spokesman did not clarify which vaccine the president would receive.

After a mild case of Covid-19, Ivan Agerton was seized by a kind of psychosis that turned life into a nightmare.
Jovelle Tamayo for The New York Times

Ivan Agerton pulled his wife, Emily, into their bedroom closet, telling her not to bring her cellphone.

“I believe people are following me,” he said, his eyes flaring with fear.

He described the paranoid delusions haunting him: that people in cars driving into their suburban Seattle cul-de-sac were spying on him, that a SWAT officer was crouching in a bush in their yard.

It was a drastic change for the 49-year-old Mr. Agerton, a usually unflappable former marine and risk-taking documentary photographer whose most recent adventure involved exploring the Red Sea for two months in a submarine. But in mid-December, after a mild case of Covid-19, he was seized by a kind of psychosis that turned life into a nightmare. He couldn’t sleep, worried he had somehow done something wrong, suspected ordinary people of sinister motives and eventually was hospitalized in a psychiatric ward twice.

“Like a light switch — it happened this fast — this intense paranoia hit me,” Mr. Agerton said in interviews over two months. “It was really single-handedly the most terrifying thing I’ve ever experienced in my life.”

Mr. Agerton’s experience reflects a phenomenon doctors are increasingly reporting: psychotic symptoms emerging weeks after coronavirus infection in some people with no previous mental illness.

Doctors say such symptoms may be one manifestation of brain-related aftereffects of Covid-19. Along with more common issues like brain fog, memory loss and neurological problems, “new onset” psychosis may result from an immune response, vascular issues or inflammation from the disease process, experts hypothesize.

Much about the condition remains mysterious. Some patients feel urges to harm others or themselves. Others, like Mr. Agerton, have no violent impulses but become almost obsessively paranoid. Some need weeks of hospitalization with doctors trying different medications, while others improve faster. Some patients relapse.

Mr. Agerton spent about a week in a psychiatric ward in December, missing Christmas with his wife and three children. By mid-January, he seemed to have recovered and his doctor planned to taper his antipsychotic medication. In February, however, “the paranoia came screaming back,” Mr. Agerton said in an interview a day before being hospitalized a second time.

Recently, Mr. Agerton said he felt considerably better, with 90 percent of the paranoia gone. His sense of smell is beginning to return. He hopes that signals lasting improvement.

It’s unclear how long he will need medication and when he will be able to resume his adventurous work.

“There’s this fear of how long is this going to happen,” he said. “How long am I going to live with this?”

Guy-Brice Parfait Kolélas addressing his supporters in Brazzaville, Republic of Congo, in 2016.
Marco Longari/Agence France-Presse — Getty Images

The leading opposition figure in the Republic of Congo died hours after polls closed in the presidential election he was contesting on Sunday. He had tested positive for the coronavirus.

The candidate, Guy-Brice Parfait Kolélas, was trying to unseat President Denis Sassou Nguesso, who has been in power for 36 years. But on Friday, Mr. Kolélas fell very ill.

As voters went to the polls on Sunday, he was evacuated by air to France for treatment. But he died on the plane on his way there, his campaign director said Monday morning at a meeting of Mr. Kolélas’s political party in Brazzaville, the Congolese capital.

Few observers expected Mr. Kolélas to win the election. But his death is nevertheless a blow for a Central African country mired in an economic crisis. The country has reported 9,564 coronavirus cases so far, and has been averaging about 34 new cases a day lately, according to a New York Times database.

A number of prominent African politicians have died in the past year. Some, like the Nigerian president’s right-hand man, Abba Kyari, and the South African cabinet minister Jackson Mphikwa Mthembu, are known to have died of Covid-19 complications. Official announcements for some others, like President John Magufuli of Tanzania and President Pierre Nkurunziza of Burundi, have said they died of heart problems, though rumors have swirled that the coronavirus played a role in their deaths.

Mr. Kolélas recorded a video on Friday from his hospital bed, telling Congolese voters that they owed it to their children to cast a ballot in the election.

“My dear compatriots, I am having trouble,” he said in the video in a weak voice, after removing an oxygen mask from his face. “I am fighting death. But I ask you to stand up and vote for change. Fight. I will not have fought in vain.”

“Rise up as one people,” he added. “Make me happy. I’m fighting on my deathbed. You, too, fight for your change.”