ImagePeople crossed the U.S.-Canadian border after Canada opened the border to vaccinated Americans in Blaine, Wash., in August. The United States will open the border for vaccinated visitors from Canada and Mexico.
Credit…David Ryder/Reuters

WASHINGTON — The Biden administration will lift travel restrictions at the borders with Canada and Mexico starting in November for fully vaccinated travelers, reopening the door of the United States to tourists and separated family members who had been sealed out of the country during the pandemic.

Foreign travelers who provide proof of vaccination and are looking to visit families or friends or shop in the United States will be allowed to enter, senior administration officials said on Tuesday, just weeks after the administration said it would soon lift a similar sweeping restriction on foreigners looking to travel to the country from overseas.

The lifting of the two bans will effectively mark the reopening of the United States to travelers and tourism, signaling a new phase in the recovery from the pandemic after the country closed its borders for nearly 19 months. But the new requirements also indicate that the country will be a welcoming destination only for those who are vaccinated.

Unvaccinated travelers will continue to be banned from crossing the borders with Mexico or Canada, officials said. Those who were never banned from traveling across the land borders, including commercial drivers and students, will also need to show proof of vaccination when crossing starting in January — an effort to provide travelers like truckers time to adjust to the new rules, officials said.

The travel restrictions, implemented in March 2020 as the coronavirus spread throughout the United States, only applied to “nonessential travelers” — relatives looking to visit family or those looking to shop in the United States, whom border communities relied on for profits. Politicians representing such communities have pleaded with the Biden administration for months to lift the travel restrictions to provide a reprieve for suffering businesses.

Senator Kirsten Gillibrand, Democrat of New York, said the travel restrictions had cost Erie County in New York at least $660 million annually.

“Finally, the New York-Canadian border will be open again to vaccinated travelers from both nations,” Ms. Gillibrand said. “This reopening will be welcome news to countless businesses, medical providers, families and loved ones that depend on travel across the northern border.”

It is unclear when specifically in November the United States will lift the travel restrictions.

Those entering at the Mexico or Canada borders will be questioned by an officer from Customs and Border Protection about their vaccination status before crossing. The border officers will have the discretion to send travelers to secondary screenings to have travel and vaccination documents checked, officials said.

While the officials said it was now safe enough to welcome in vaccinated visitors, President Biden will continue to use a separate border policy implemented early in the pandemic to rapidly turn away migrants seeking protection or economic opportunity — a policy that has been received criticism from a top State Department official and the administration’s own medical consultants.

The decision to reopen the land borders was in part made to ensure that the United States reopened to foreigners traveling by air and land at the same time, officials said. While those traveling by airplane will need to show both proof of vaccination and a negative coronavirus test to enter the United States, there will be no testing requirement for those crossing the land border.

The Centers for Disease Control and Prevention considers people fully inoculated two weeks after they receive the second dose of the Pfizer-BioNTech or Moderna vaccine, or a single dose of Johnson & Johnson’s.

Those who have received vaccines listed for emergency use by the World Health Organization, such as AstraZeneca’s, would also be considered fully vaccinated — a standard one senior official said would probably be applied to those crossing the land border. Officials added that the C.D.C. was still discussing whether foreigners crossing from Canada or Mexico with two doses from different vaccines could enter.

The decision to lift the restrictions on air travel had been celebrated by business leaders overseas and in the United States. Travel spending dropped nearly in half to about $600 billion in 2020 from a year earlier, according to the U.S. Travel Association, a trade group.

And businesses in places from Buffalo to San Diego to South Texas rely on tourists or those making a short visit to shop before returning home.

“Border communities have been hamstrung because of port closures,” Representative Veronica Escobar, a Texas Democrat who represents a border district, said in an interview. “Not only did we suffer more significant health devastation in 2020, but the economic devastation has been longer for us because of those port closures.”

“This is great, and long overdue, news,” she added.

Senator Patty Murray, Democrat of Washington, said the lifting of the restrictions would benefit communities she represents like Point Roberts, a town detached from the rest of her state “almost entirely dependent on cross-border travel to sustain their economy.”

But she warned that after “months of economic calamity” inflicted largely by the border closure, more would be needed to ensure that the community could fully recover.

Nicholas Fandos contributed reporting.

Credit…Kevin Dietsch/Getty Images

American Airlines and Southwest Airlines, citing federal requirements, said on Tuesday that they would not comply with an order from the governor of Texas barring private employers from mandating coronavirus vaccines in the state.

Gov. Greg Abbott, a strong opponent of vaccine mandates, issued the order on Monday, saying inoculation against Covid-19 should “always be voluntary for Texans.”

“We believe the federal vaccine mandate supersedes any conflicting state laws, and this does not change anything for American,” said a spokeswoman for the airline, which is based in Fort Worth. Southwest, which is based in Dallas, said it would “remain compliant” with the federal mandate.

The Greater Houston Partnership, a business group that counts Exxon Mobil, Chevron and JPMorgan Chase as members, also came out on Tuesday against Mr. Abbott’s order, saying it “does not support Texas businesses’ ability and duty to create a safe workplace.”

President Biden announced last month that federal contractors and their employees would need to be vaccinated, with limited exceptions. Like other major employers, American and Southwest cited that requirement and their status as contractors in announcing that employees must be vaccinated.

Mr. Biden also announced that workers at companies with more than 100 employees would have to be vaccinated or tested regularly, but those requirements are dependent on new rules that the Occupational Safety and Health Administration has not issued yet. That requirement will cover tens of millions of workers, the administration said. Health care workers at institutions that receive funding from Medicaid and Medicare are also required to be vaccinated.

Jen Psaki, the White House press secretary, accused Mr. Abbott on Tuesday of putting “politics ahead of public health” and said federal laws superseded state and local ones.

The administration will continue to pursue the expansive mandates it announced last month, she said, adding that business leaders who had already introduced mandates had reported positive results.

“Beyond the legal aspect, which is unquestionable in our view, the question for any business leader is: What do you want to do to save more lives in your companies?” Ms. Psaki said.

A spokeswoman for Mr. Abbott said that the Biden administration had “left employers with the unfair choice of either violating federal regulations or losing their valued employees” and that the governor’s order was “enforceable by state and local law enforcement.”

Late Tuesday, a federal judge in Texas issued a temporary restraining order telling United Airlines not to place on unpaid leave any employee who had been granted a vaccine exemption. The court’s order said it was not ruling on any merits of the case, but was allowing for more time to consider a preliminary injunction. The order is in place until Oct. 26.

In Florida, another state with a governor who has battled vaccine mandates, the Department of Health issued a notice of violation to Leon County, which encompasses Tallahassee, for violating a ban on “vaccine passports” in the state.

The department said in a release on Tuesday that it was fining the county nearly $3.6 million for requiring 700 government employees to provide their vaccine status and firing 14 who refused to comply. Gov. Ron DeSantis said he wanted to “preserve the ability of Floridians to make their own decisions regarding what shots to take.”

Credit…Matthew Busch for The New York Times

An order by the governor of Texas barring nearly all Covid-19 vaccine mandates in the state appears sweeping. But legal experts say that it does not supersede President Biden’s orders requiring vaccine mandates for many kinds of employees, and that it is likely to be challenged in court, where the case law so far has been heavily in favor of the validity of vaccine requirements.

The order issued on Monday by Gov. Greg Abbott of Texas, a Republican, bars vaccine mandates by any “entity” — including private employers, who were not covered by his previous orders forbidding mandates. States like Florida have also acted to ban public agencies and private businesses from requiring vaccination, and those bans are also likely to end up in court, experts say.

“Texas has just set itself up for a grand political show, but not a potentially legally sound initiative to stop all vaccine mandates,” said James Hodge, the director of the Center for Public Health Law and Policy at Arizona State University. “It boils down to a lot more politics than law.”

Courts in the United States have a long history of upholding vaccine mandates, Mr. Hodge said, and of ruling that protecting public health takes precedence over personal choice.

“That individual right to liberty has never gone that far to actually engage in behaviors that directly impact the public’s health,” said Mr. Hodge.

The right of the government to impose vaccine mandates has been established at least since 1905, when the Supreme Court ruled that Cambridge, Mass., could require adults there to be vaccinated against smallpox. Later court cases set the legal groundwork for vaccine mandates in schools, health care and other fields, Mr. Hodge said.

The Texas order also ramps up an emerging battle between Republican governors and President Biden, who is testing the limits of presidential power by asserting executive authority to require Covid-19 vaccines for workers in the federal government and the health care industry.

The president has also moved to require that all companies with more than 100 workers maintain safe workplaces through vaccination or weekly testing, relying on the federal government’s power to regulate commerce and the Occupational Safety and Health Act of 1970.

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Abbott ‘Putting Politics Ahead of Public Health,’ Psaki Says

Jen Psaki, the White House press secretary, criticized Gov. Greg Abbott of Texas for signing an executive order banning vaccine mandates, and said that it does not supersede President Biden’s orders requiring vaccinations for many kinds of employees.

Governor Abbott’s executive order banning mandates, and I would also note announcement by Governor DeSantis this morning essentially banning the implementation of mandates fit a familiar pattern that we’ve seen of putting politics ahead of public health. Over 700,000 American lives have been lost due to Covid-19, including more than 56,000 in Florida and over 68,000 in Texas. And every leader should be focused on supporting efforts to save lives and end the pandemic. Why would you be taking steps that prevent the saving of lives, that make it more difficult to save lives across the country or in any state? And I would also note that vaccine requirements have been standard in both the Lone Star State, Texas in case you’re not familiar, and the Sunshine State, Florida, in schools for decades. Whether polio, measles, mumps, rubella, the chickenpox, there are vaccine requirements that have been implemented for decades in these states. Bottom line is we’re going to continue to implement the law, which the president of the United States has the ability, the authority, the legal authority to do, and we are going to continue to work to get more people vaccinated to get out of this pandemic. The president will use every lever at his disposal to do that.

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Jen Psaki, the White House press secretary, criticized Gov. Greg Abbott of Texas for signing an executive order banning vaccine mandates, and said that it does not supersede President Biden’s orders requiring vaccinations for many kinds of employees.CreditCredit…Sarahbeth Maney/The New York Times

Jen Psaki, the White House press secretary, said on Tuesday that the president’s legal authority to issue mandates “overrides state law,” and that “to get out of this pandemic, the president will use every lever at his disposal.”

Republican governors like Mr. Abbot and Ron DeSantis of Florida have accused Mr. Biden of overreach. Mr. DeSantis said at a news conference on Tuesday that Florida and other states were prepared to mount a legal challenge to Mr. Biden’s mandate for private employers. But the states are likely to lose in court, experts say.

“It’s highly unlikely that you’re going to see any sort of higher-level court consistently agree that this type of intervention exceeds federal authority, when it’s been in place for 50 years,” Mr. Hodge said.

In August, a federal judge ruled against Florida’s ban on “vaccine passport” requirements. Ruling on First Amendment grounds, the judge issued a temporary injunction allowing Norwegian Cruise Line to continue requiring its embarking passengers to show proof of vaccination, despite the state ban.

Correction: 

An earlier version of this article misstated the year that the Supreme Court ruled governments have the right to impose vaccines. It was 1905, not 1904.

Credit…Bess Adler for The New York Times

The Food and Drug Administration set the stage Tuesday for a new round of decisions on which Americans should get coronavirus booster shots, releasing a review of data suggesting that an additional half-dose of Moderna’s vaccine at least six months after the second dose increased antibody levels. But the agency did not take a position on whether an additional shot was necessary.

An independent advisory panel of experts will examine the available data on both Moderna and Johnson & Johnson boosters in a two-day meeting later this week. Votes are scheduled on whether to recommend emergency authorization of boosters for both vaccines. While the panel’s votes are not binding, the F.D.A. typically follows them.

In documents released Tuesday, Moderna argued that a third injection is needed because the potency of its vaccine wanes over time, with levels of neutralizing antibodies falling six to eight months after a second dose. The company also cited “real world evidence of reduced effectiveness against the Delta variant,” although the F.D.A. noted that the studies diverge on whether Moderna’s protection weakened over time against symptomatic infection or against the Delta variant.

The company did not argue that a booster was necessary to prevent severe disease or hospitalization, but concentrated its arguments on preventing infection and mild to moderate disease.

Moderna said the mean antibody level of participants in its study was 1.8 times higher after the booster than it was after the second shot. In another measurement, the booster raised neutralizing antibodies at least fourfold in 87.9 percent of people compared to after the second dose, thus narrowly failing to meet the agency’s requirement of 88.4 percent.

In a document that Johnson & Johnson submitted to the F.D.A. ahead of this week’s meeting, the company argued that booster shots of its vaccine increased protection against Covid-19, including against severe forms of the disease, and increased the strength of the body’s immune response against virus variants. Johnson & Johnson said that a booster shot could be administered as early as two months after the first dose, but recommended doing so at least six months after, when it said recipients had been shown to have a more robust immune response.

Noah Weiland contributed reporting.

Credit…Andrew Testa for The New York Times

Britain’s initial response to the Covid-19 pandemic “ranks as one of the most important public health failures the United Kingdom has ever experienced,” a parliamentary inquiry has found, blaming the British government for “many thousands of deaths which could have been avoided.”

In a highly critical, 151-page report, two committees of lawmakers wrote that the government’s failure to carry out widespread testing or swiftly impose lockdowns and other restrictions amounted to a pursuit of “herd immunity by infection” — accepting that many people would get the coronavirus and that the only option was to try to manage its spread.

“It is now clear that this was the wrong policy, and that it led to a higher initial death toll than would have resulted from a more emphatic early policy,” the report concluded.

Although many of its findings were already known, the report grew out of the first authoritative investigation of Britain’s pandemic response. The inquiry, led by lawmakers from Prime Minister Boris Johnson’s own Conservative Party, described a litany of failures by his government in the months after the first coronavirus cases were detected in Britain in January 2020.

Britain has experienced one of the worst Covid-19 outbreaks among wealthy nations, with 162,000 deaths officially attributed to the disease. Like many Western democracies, at the outset of the pandemic it struggled to balance individual liberties with strict measures such as lockdowns, and suffered from mismanagement at the top levels of government.

The country has tried to put those missteps behind it, racing ahead last winter and spring as one of the world leaders in vaccinations, with more than three-quarters of people 12 and older having now received two doses of a Covid vaccine. As deaths declined from prior peaks, Britain cast off nearly all restrictions, and even though infections remain high, Mr. Johnson has tried to portray the country as having put the worst of the pandemic behind it.

But as he struggles against a raft of new economic problems, the report renewed criticisms of his government’s handling of the virus. It does not require the government to act, but its findings are likely to influence the public debate for months to come. A full public inquiry promised by Mr. Johnson is not scheduled to begin until next year.

“This report lays bare the failings of the U.K. government to contain Covid, including delayed border measures, nonexistent testing for weeks, lack of P.P.E. for frontline workers and a late lockdown,” said Devi Sridhar, the head of the global public health program at the University of Edinburgh. “Hopefully, lessons will be learned from this.”

Credit…Adam Hunger via Associated Press

The Nets announced Tuesday that they were indefinitely barring Kyrie Irving from all games and practices until he was “eligible to be a full participant.”

Irving, the team’s starting point guard, had faced the prospect of being able to play only on the road with the Nets this season because of local coronavirus ordinances in New York that require most individuals to be at least partially vaccinated to enter facilities such as sports arenas. The Nets play their home games at Barclays Center in Brooklyn.

“Without a doubt, losing a player of Kyrie’s caliber hurts,” Sean Marks, the Nets’ general manager, said at a news conference. “I’m not going to deny that. But at the end of the day, our focus, our coaches’ focus and our organization’s focus needs to be on those players that are going to be involved here and participating fully.”

Irving has not spoken publicly about his vaccination status, asking instead for privacy, and the Nets had danced around the topic for weeks. In response to a question from The New York Times on Tuesday about whether Irving was vaccinated, Marks said: “If he was vaccinated, we wouldn’t be having this discussion. I think that’s probably pretty clear.”

Marks said Irving would not be paid for missed home games, and that the decision to keep Irving away from the team had been made by himself and by Joe Tsai, the Nets’ owner.

“Will there be pushback from Kyrie and his camp? I’m sure that this is not a decision that they like,” Marks said. “Kyrie loves to play basketball, wants to be out there, wants to be participating with his teammates. But again, this is a choice that Kyrie had and he was aware of that.”

Irving missed the Nets’ preseason home-opener against the Milwaukee Bucks after being listed as “ineligible” on the injury report. He also was not with the Nets in Philadelphia for their preseason game against the 76ers on Monday. Asked about his absence before the game, Steve Nash, the Nets’ coach, said: “We’re just trying to take our time to figure out what everything means.”

Irving’s potential absence from home games had created a predicament for the Nets, a team with championship aspirations that had to weigh whether having him around only half the time would be worth it. His teammates had expressed their support for him.

“It’ll work itself out,” James Harden said last week, adding: “I want him to be on the team, of course. He’s been a huge part of our success.”

On Tuesday, Marks said he would be willing to welcome Irving’s return to the team “under a different set of circumstances.”

Barclays Center and Madison Square Garden, where the Knicks play, require all employees and guests 12 and older to show proof of having received at least one vaccine dose, to comply with a city mandate, unless they have a religious or medical exemption. San Francisco has a similar requirement that applies to Chase Center, where the Golden State Warriors play. The mandates in both cities mean that the players from the Knicks, Nets and Golden State cannot play in their teams’ 41 home games without being vaccinated.

The ordinances in New York and San Francisco do not apply to players from visiting teams.

Credit…Yana Paskova for The New York Times

A federal judge ruled on Tuesday that New York State health officials must allow employers to grant religious exemptions to a Covid-19 vaccine mandate for health care workers while a lawsuit challenging the mandate makes its way through the courts.

The judge’s order at least temporarily thwarts part of Gov. Kathy M. Hochul’s effort to require vaccination for all health care workers. It offers a reprieve for thousands of unvaccinated doctors, nurses and support workers who had applied for religious exemptions, and who would have been prevented from working beginning Tuesday if the judge had ruled for the state. The mandate remains in effect for all other health care workers.

A lawyer for a group of workers who are suing the state over the mandate hailed the ruling.

“With this decision, the court rightly recognized that yesterday’s ‘front line heroes’ in dealing with Covid cannot suddenly be treated as disease-carrying villains and kicked to the curb by the command of a state health bureaucracy,” said Christopher Ferrara of the Thomas More Society.

Ms. Hochul, in a statement, indicated the state would appeal.

“My responsibility as governor is to protect the people of this state, and requiring health care workers to get vaccinated accomplishes that,” Ms. Hochul said. “I stand behind this mandate, and I will fight this decision in court to keep New Yorkers safe.”

Former Gov. Andrew M. Cuomo issued the state’s first vaccine mandate for health workers in mid-August; it permitted religious exemptions.

But when Ms. Hochul’s administration issued its own mandate later that month — to take effect this fall — it rescinded the exemptions. That prompted 17 health care workers to sue the state in federal court, on the ground that the mandate conflicted with their religious beliefs.

Between the two governors’ orders, thousands of health care workers across the state had applied for or received a religious exemption.

In his 27-page ruling, Judge David N. Hurd of the Northern District in Utica wrote that New York appeared to overreach by barring all religious accommodations in the mandate. He issued a preliminary injunction preventing the Department of Health from acting against any employer who grants religious exemptions, and wrote that the 17 health care workers were likely to succeed in their case.

“The Department of Health is barred from interfering in any way with the granting of religious exemptions from Covid-19 vaccination going forward, or with the operation of exemptions already granted,” Judge Hurd wrote.

The judge had earlier issued a temporary restraining order barring the state from enforcing the mandate against people with religious objections starting in mid-September; technically, Tuesday’s order extended that ruling. The restraining order effectively allowed many health workers who applied for religious exemptions in New York to continue working even after the mandate went into effect.

In the federal case, titled Dr. A et al v. Hochul, the 17 health care workers argued that they could not consent to be inoculated with vaccines “that were tested, developed or produced with fetal cell lines derived from procured abortions.”

Pope Francis has said that Catholics may get the Covid-19 vaccines; most of the health care workers suing in the case are Catholic. But Judge Hurd did not question whether the health care workers were correct in their religious objections. Instead, he focused on their broader constitutional right to have their religious beliefs considered, and when possible, accommodated.

In his ruling on Tuesday, Judge Hurd looked at how the mandates differed from one governor to the next. “This intentional change in language is the kind of ‘religious gerrymander’ that triggers heightened scrutiny,” the judge wrote.

Credit…Hector Retamal/Agence France-Presse — Getty Images

More than 700 people have applied for spots on a new committee charged with breathing life into the World Health Organization’s stalled inquiry into the origins of the coronavirus pandemic, despite the considerable challenges the investigation presents.

The committee, expected to be announced this week, represents an attempt by the embattled global health body to reset its approach to determining how the pandemic began. Nine months after sending a team of international experts to China, only for its findings to become entangled in geopolitics and trailed by concerns over Beijing’s influence, the W.H.O. is trying to inoculate its latest efforts from the slightest hints of undue deference toward China.

Its new advisory team will include specialists in fields like laboratory safety and biosecurity, a step that analysts say may help placate Western governments pressing for consideration of whether the virus emerged from a lab. And, crucially, the committee will have a mandate to weigh in on the emergence of any new pathogens beyond this novel coronavirus, giving it a permanence that could help insulate it from political squabbling and strengthen the W.H.O.’s hand for future outbreaks.

Maria Van Kerkhove, the W.H.O.’s Covid-19 technical lead, said the group — comprising some two dozen virologists, geneticists, animal experts and safety and security specialists — would help the organization return to its roots amid the rancor and partisanship of the coronavirus origins debate.

But what most needs doing in the hunt for Covid’s origins, many scientists believe, is something that the new advisory group will be powerless to achieve: persuading China to release evidence about the first infections and to let researchers inspect virology labs, bat caves and wildlife farms within its borders.

Credit…Adam Dean for The New York Times

Fully vaccinated travelers from low-risk countries, including the United States and China, would be allowed to visit Thailand without undergoing quarantine starting Nov. 1, under a plan announced by the country’s prime minister, Prayuth Chan-ocha.

Health officials are expected to approve the plan, which calls for the lifting of restrictions for tourists from 10 countries. It would be the first step in a phased reopening strategy that would lead to the resumption of service at entertainment venues as early as Dec. 1, he said in an address Monday evening.

Before the pandemic, Thailand’s economy was highly dependent on tourism and attracted nearly 40 million tourists in 2019, with more than a quarter coming from China. Bangkok, the capital, often ranks in surveys as the world’s most visited city. Thailand was among the most successful countries in containing the virus last year. But it was slow in procuring vaccines and has seen a surge of cases this year.

The prime minister said that Thailand must learn to live with the virus, noting that other nations were already taking steps to reopen to tourists, and that Thailand must act quickly to lure millions of visitors for the New Year holidays.

Under Mr. Prayuth’s plan, fully vaccinated visitors from the 10 countries would be required to show proof of a negative PCR test before departure, and to take another test upon arrival. After testing negative, they would be free to travel around Thailand. Visitors from countries not on the list would still face quarantines and other restrictions.

A ban on restaurants serving alcohol — a rule widely flouted in Bangkok — would remain in place until at least Dec. 1, he said.

In July, Thailand began allowing vaccinated tourists who tested negative to visit the island of Phuket under a program called the Phuket Sandbox. After 14 days, they were allowed to travel freely in Thailand. That period has since been reduced to seven days. Thailand has increased its vaccine supply in recent weeks and launched an aggressive inoculation campaign, vaccinating as many as 1 million people a day.

“The time has come for us to ready ourselves to face the coronavirus and live with it as with other endemic infections and disease,” Mr. Prayuth said.

Credit…Thomas Kienzle/Agence France-Presse — Getty Images

The German company CureVac announced on Tuesday that it was withdrawing its mRNA vaccine for Covid-19 from the approval process in Europe. The company pulled the plug after determining that it might take until June for regulators to make a ruling about the vaccine.

With other mRNA vaccines from Moderna and Pfizer-BioNTech already in wide distribution, the company decided it was time to give up on its initial efforts to address the Covid-19 emergency.

“The pandemic window is closing,” Franz-Werner Haas, CureVac’s chief executive, said in an interview.

The company will also terminate its advance agreement with the European Commission to sell it 405 million doses of the vaccine after approval.

But in the longer term, CureVac is not out of the Covid-19 vaccine business. The company is partnering with the pharmaceutical giant GSK to start a clinical trial of a new version of the vaccine that they hope will be more effective. The companies are also investigating how to combine seasonal booster shots to work against both Covid-19 and influenza.

Founded 20 years ago, CureVac pioneered early research on mRNA vaccines along with the German firm BioNTech and the U.S. company Moderna. At the start of the Covid-19 pandemic, all three companies developed new vaccines against the coronavirus.

While Moderna and BioNTech moved swiftly into clinical trials, CureVac was slower to find partners to support its vaccine’s development. Nevertheless, some experts saw promise in the CureVac shot, hoping that it could help address the global shortfall in Covid vaccines.

The European Medicines Agency gave CureVac special priority for its application, cutting the time needed for authorization. But in June, the company made a disappointing announcement: A clinical trial found that the vaccine’s efficacy was just 48 percent. By comparison, the vaccines from BioNTech and Moderna had efficacies around 95 percent.

Despite that disappointment, CureVac went ahead with its application for authorization in Europe, and submitted a final data package in September. In its updated application, CureVac asked that the vaccine be considered only for people 18 to 60 years old. In that group, the clinical trial had found a moderately higher vaccine efficacy, of 53 percent.

The European regulators’ response was less than encouraging. “We were not being lined up for emergency review,” said Dr. Klaus Edvardsen, the company’s chief development officer.

CureVac’s Covid-19 vaccine is now the seventh to be abandoned after entering clinical trials. Last month, Sanofi announced it was giving up on its mRNA vaccine.

But CureVac’s newer version may have more success. In August, the company shared the results of an experiment on monkeys, showing that the new vaccine generated 10 times as many antibodies against the coronavirus as the original one did. CureVac will begin testing it in people in the next couple of months.

Dr. Haas said the company’s strategy is now “to be fast with a second generation rather than to be very late with the first generation.”

Correction: 

An earlier version of this article misstated the efficacy of the CureVac vaccine. It was 48 percent, not 47. It also misstated the age range for which the company asked regulators to consider vaccine approval. It was ages 18 to 60, not under 65.

Credit…Seth Wenig/Associated Press

In their struggle to convince holdouts to get vaccinated against Covid, governments around the world are embracing vaccine mandates.

The push to get people vaccinated has largely shifted from offering incentives, like cash payouts or free drinks, to issuing mandates and restricting the access of the unvaccinated to many venues and activities.

Care to sip an espresso indoors at a cafe in Paris? You will need to provide proof of vaccination or a fresh negative coronavirus test, for which unvaccinated people will have to pay beginning on Oct. 15.

Want to work in settings like offices, factories, shops and restaurants in Italy? Starting later this month, you will need to have recently recovered from Covid-19, provide proof of having received at least one dose of a vaccine, or get a coronavirus test every two days. In areas of high coronavirus transmission in Greece, live music is returning indoors to restaurants and bars for a two-week trial, but the unvaccinated will not be admitted.

Italian and French officials announced their measures in July. Greece announced its shift last week. In early August, New York became the first U.S. city to require proof of vaccination for indoor dining, gyms and movie theaters.

Since then, San Francisco, Los Angeles and other cities have announced their own vaccine requirements to engage in public activities.

As the latest wave of infections has begun to wane around much of the U.S., President Biden’s administration has increasingly turned to mandates, drawing fire in the process from many Republican leaders who perceive them as government overreach. On Thursday, he urged private employers to impose mandates of their own as the Occupational Safety and Health Administration works out the details of a vaccine or testing requirement for companies with more than 100 employers.

Vaccine mandates have sparked resentment and refusal to comply from the unvaccinated.

France’s restrictions spurred large protests this summer, but those protests have mostly cooled, and as of Oct. 7, 67 percent of the population was fully vaccinated, more than double the level from early July, according to the Our World in Data project at the University of Oxford. An additional 8.3 percent were partly vaccinated as of Oct. 7.

Vaccine requirements remain politically toxic in some parts of the United States. Republican governors like Greg Abbott of Texas and Ron DeSantis of Florida have enacted rules that penalize businesses that require proof of vaccination and prohibit local governments from mandating such requirements.

On Monday, Mr. Abbott signed an executive order that broadened a previous ban on vaccine mandates by barring private companies from imposing them.

“The COVID-19 vaccine is safe, effective, and our best defense against the virus, but should remain voluntary and never forced,” the governor said in a statement.

The A.C.L.U., on the other hand, has defended vaccine mandates, saying they protect the civil liberties the organization defends.

“They protect the most vulnerable among us, including people with disabilities and fragile immune systems, children too young to be vaccinated and communities of color hit hard by the disease,” David Cole, the national legal director of the A.C.L.U., and Daniel Mach, director of its program on freedom of religion and belief, wrote in a New York Times editorial in September.

Some organizations that encourage vaccinations feel that mandates could be counterproductive, like the Wyoming Hospital Association. Eric Boley, the association’s president, said that vaccination was critical, especially for health workers, but that mandates could drive away staff that Wyoming’s hospitals urgently need.

Credit…Joe Raedle/Getty Images

By the holiday season, flying will have changed significantly for Americans returning to the United States from abroad. They will be asked to show proof that they are vaccinated, to commit to two coronavirus tests if they are not and to participate in a new contact tracing system.

For Americans traveling within the United States, however, none of this applies. As airlines prepare for what’s expected to be the biggest travel rush of the past two years, domestic travel — aside from a mask mandate and some restrictions on alcohol — will be largely the same as it was before the pandemic: packed cabins and no testing or proof of vaccination required.

Whether this is a symptom of denial or a sign of progress depends on whom you ask. Senator Dianne Feinstein, Democrat of California, recently telegraphed her position when she proposed a bill that would require passengers on domestic flights to be fully vaccinated, to have recently tested negative or to have a certificate of recovery from the virus.

“We know that air travel during the 2020 holiday season contributed to last winter’s devastating COVID-19 surge,” Ms. Feinstein said in a statement. “We simply cannot allow that to happen again.”

Dr. Anthony S. Fauci, President Biden’s top medical adviser, has said he personally supports requiring proof of vaccination for domestic air travel, a policy that Canada will begin putting in place on Oct. 30. But the White House has said it is focused on other strategies for encouraging broad vaccination.

Credit…Fabio Bucciarelli for The New York Times

On Jan. 9, 2020, about a week after the world first learned of a mysterious cluster of pneumonia cases in central China, authorities announced that scientists had found the culprit: a novel coronavirus.

It was a sobering announcement, and an unnervingly familiar one. Nearly two decades earlier, a different coronavirus had sped around the world, causing a lethal new disease — severe acute respiratory syndrome, or SARS. It killed 774 people before health officials contained it.

But even as scientists worried that history may be repeating itself, there was one glimmer of hope. Although all viruses evolve, coronaviruses are known to be relatively stable, changing more slowly than the common flu.

What many scientists had not counted on was unchecked global spread. Over the following weeks, the new virus, SARS-CoV-2, skipped from Wuhan, China, to a cruise ship in Japan, to a small town in northern Italy and to a biotechnology conference in Boston. Country by country, global coronavirus trackers turned red.

To date, more than 237 million people have been infected with the virus, and 4.8 million have died — 700,000 in the United States alone.

With every infection come new opportunities for the virus to mutate. Now, nearly two years into the pandemic, we are working our way through an alphabet of new viral variants: fast-spreading Alpha, immune-evading Beta, and on through Gamma, Delta, Lambda and, most recently, Mu.

Even for a virus, evolution is a long game, and our relationship with Covid-19 is still in its infancy. We are extremely unlikely to eradicate the virus, scientists say, and what the next few years — and decades — hold is difficult to predict.

But the legacy of past epidemics, as well as some basic biological principles, provides clues to where we could be headed.

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It’s difficult to parse how immunity from infection from the coronavirus and from vaccination compare. Dozens of studies have delved into the debate, and have drawn contradictory conclusions.

Some consistent patterns have emerged. Two doses of an mRNA vaccine produce more antibodies, and more reliably, than an infection does. But the antibodies from a previous infection are more diverse, capable of fending off a wider range of variants, than those produced by vaccines.

Studies touting the durability and strength of natural immunity are hobbled by one crucial flaw. They are, by definition, assessing the responses only of people who survived Covid-19.

Only 85 percent to 90 percent of people who test positive for the virus and recover have detectable antibodies to begin with. The strength and durability of the response is variable.

For example, while the immunity gained from vaccines and infection is comparable among younger people, two doses of the mRNA vaccines protected adults older than 65 better than a prior infection did.

Research published in May showed a stepwise increase in the level of antibodies with rising severity of infection. About 43 percent of recovered people had no detectable neutralizing antibodies — the kind needed to prevent reinfection — according to one study. The antibodies drop to undetectable levels after about two months in about 30 percent of people who recover.

Several studies have now shown that reinfections, at least with the earlier versions of the virus, are rare.

At the Cleveland Clinic, none of 1,359 health care workers who remained unvaccinated after having Covid-19 tested positive for the virus over many months.

But the clinic tested only people who were visibly ill, and may have missed reinfections that did not produce symptoms. The participants were 39 years old on average, so the results may not apply to older adults, who would be more likely to become infected again.

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Covid-19’s waves of destruction have inflicted their own kind of despair on humanity in the 21st century, leaving many to wonder when the pandemic will end.

“We tend to think of pandemics and epidemics as episodic,” said Allan Brandt, a historian of science and medicine at Harvard University. “But we are living in the Covid-19 era, not the Covid-19 crisis. There will be a lot of changes that are substantial and persistent. We won’t look back and say, ‘That was a terrible time, but it’s over.’ We will be dealing with many of the ramifications of Covid-19 for decades, for decades.”

Especially in the months before the Delta variant became dominant, the pandemic seemed like it should be nearly over.

“When the vaccines first came out, and we started getting shots in our own arms, so many of us felt physically and emotionally transformed,” said Dr. Jeremy Greene, a historian of medicine at Johns Hopkins University School of Medicine. “We had a willful desire to translate that as, ‘The pandemic has ended for me.’”

He added, “It was a willful delusion.”

That is a lesson from history that is often forgotten, Frank Snowden, a historian of medicine at Yale University, said: how difficult it is to declare that a pandemic has ended.

It may not be over even when physical disease, measured in illness and mortality, has greatly subsided. It may continue as the economy recovers and life returns to a semblance of normality. The lingering psychological shock of having lived in prolonged fear of severe illness, isolation and painful death takes long to fade.

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Many law enforcement officers in the United States resist coronavirus vaccination even though Covid-19 has killed more law enforcement officers than any other work-related cause since the start of the pandemic.

More than 460 American law enforcement officers have died from Covid-19 infections tied to their work since the pandemic began, according to the Officer Down Memorial Page, making the coronavirus by far the most common cause of duty-related deaths in 2020 and 2021. More than four times as many officers have died from Covid-19 as from gunfire during the pandemic. There is no comprehensive accounting of how many American police officers have been sickened by the virus, but departments across the country have reported large outbreaks in the ranks.

While the virus has ravaged policing, persuading officers to take a vaccine has often been a struggle, even though the shots have proven to be largely effective in preventing severe disease and death.

Health departments generally do not publish vaccination data by occupation, but some cities have released figures showing that police department employees have been vaccinated at lower rates than most other government workers, and at lower rates than the general public. In Los Angeles, where vaccines are required for city workers, more than 2,600 employees of the police department said they intended to seek a religious exemption, though almost all major religious denominations support vaccines.

Some elected officials say police officers have a higher responsibility to get vaccinated because they are regularly interacting with members of the public and could unknowingly spread the virus. The debate echoes concerns from earlier in the pandemic, when police officers in some cities resisted wearing masks in public.

Yet as more departments in recent weeks have considered requiring members to be vaccinated, officers and their unions have loudly pushed back, in some cases threatening resignations or flooding systems with requests for exemptions.