Security officers stood guard outside the Wuhan Institute of Virology during a visit in February by members of the World Health Organization team investigating the origins of the pandemic.
Thomas Peter/Reuters

With new attention on the origins of the coronavirus, experts and officials on Sunday called on China to provide greater transparency and speed inquiries into whether the devastating pandemic began with a leak from a lab.

“There’s going to be Covid-26 and Covid-32 unless we fully understand the origins of Covid-19,” Peter J. Hotez, dean of the National School of Tropical Medicine at Baylor College of Medicine and co-director of the Texas Children’s Hospital Center for Vaccine Development, said on the NBC program “Meet the Press.”

On Wednesday, President Biden ordered U.S. intelligence agencies to “redouble their efforts” to find out where the virus originated, giving them 90 days to examine two theories: that the virus was accidentally leaked from a lab in China or that it was first transmitted from animal to humans outside a lab. Suspicions have focused on the Wuhan Institute of Virology, which long gathered bat viruses and whose laboratories conducted experiments on them. It is based in the city where the coronavirus first emerged.

An investigation this year by the World Health Organization largely dismissed the possibility that the virus escaped from the institute, but many critics faulted the effort as lacking the wide access necessary to determine its origins.

Mr. Biden has said he hopes the investigation he has ordered, which will include unexamined intelligence, will bring the United States “closer to a definitive conclusion” about the virus. He has committed to releasing the report publicly.

Dr. Hotez said on Sunday that the inquiry might not yield much new information because the United States had already “pushed intelligence about as far as we can.” He suggested that the world needed a sweeping new scientific search for outbreak answers, most especially in China.

“There’s a lot going for natural origins,” he said of the leading theory, but an independent team of scientists, epidemiologists and virologists would need to work in China for a period of six months to a year so the world can “fully unravel the origins of Covid-19.” The team would have to interview scientists and scrutinize their lab notebooks in order to investigate the possibility of a lab leak, he said.

Asked if that could be done without China’s cooperation, Dr. Hotez said no. “I think we have to really put a lot of pressure on China,” he said, including possible sanctions, to secure “unfettered access” for a team of top scientists.

Chinese state media outlets continued to deliver a defiant response to such calls. On Sunday, an editorial in Global Times, a Chinese news site that echoes Beijing’s line, ridiculed Mr. Biden’s push for new intelligence and called any findings “preset” to be a laboratory in Wuhan. United States intelligence agencies, it said, “do not have superior research capability” than the World Health Organization, or more information.

“What they will get in the end is nothing but political,” the editorial said.

Matthew Pottinger, who served as deputy national security adviser to former President Donald J. Trump, presented a contrast to Dr. Hotez in assessing the prospects of Mr. Biden’s investigation.

“I think that there’s actually an enormous amount that could come out,” Mr. Pottinger said, also on “Meet the Press.”

He said Mr. Biden’s call for a fresh look at the evidence and the intelligence could prompt scientists in China to step forward — even at the risk of angering Beijing.

“If this thing came out of a lab, there are people in China who probably know that,” he said. The new initiative, Mr. Pottinger added, “might provide moral courage to many of these ethical scientists in China, for whom I think this is weighing on their consciences. I think that we’re going to see more information come out as a result of this inquiry.”

Representative Michael McCaul, Republican of Texas and ranking member of the House Foreign Affairs Committee, told CNN’s “State of the Union” on Sunday that intercepted intelligence communications had provided intriguing clues pointing to a lab leak.

“We have signals intelligence and human and other forms of intelligence,” he said, that while not certain in nature, suggest a lab leak is “more likely than not.”

That was in contrast to an earlier report that federal officials had intercepted no such communications in China that provided any strong evidence of the theory. Collecting so-called signals intelligence — electronic communications or phone calls — is notoriously difficult in China.

Michael Shear contributed reporting.

Estadio Monumental, one of the previously scheduled sites for the Copa América soccer tournament, being disinfected in Buenos Aires last month.
Pool photo by Natacha Pisarenko

Organizers of the Copa América, South America’s largest soccer tournament, said Sunday that it would no longer take place in Argentina, which is mired in its worst coronavirus surge to date.

It is unclear where the 10-nation tournament, which is set to start June 13, will now take place. But the South American soccer federation, Conmebol, which organizes the event, said it would consider offers to move it to other countries that had expressed interest.

The Argentine government and public have been torn over the wisdom of hosting the monthlong tournament, in a discussion that mirrors the one taking place in Japan over holding the Tokyo Olympics this summer. On Friday, officials in Japan, which is recording more than 4,000 cases a day amid a fourth wave of infections, extended a state of emergency in Tokyo and eight other prefectures until at least June 20, just over a month before the opening ceremony.

Last week, President Alberto Fernández of Argentina announced stringent lockdown measures until the end of the month, calling this his country’s “worst moment in the pandemic.” Argentina now ranks third in the world, after neighboring Paraguay and Uruguay, in the number of deaths per capita over the past week, according to a New York Times database. The country of 45 million is reporting an average of more than 30,000 new cases a day, compared with 20,000 in the United States.

Mr. Fernández also met last week with Alejandro Domínguez, the head of Conmebol, and presented a “strict protocol” for holding the tournament if the soccer federation wanted it to go ahead in Argentina as planned.

The 2020 edition of the Copa América was postponed by a year last spring after the start of the pandemic. In soccer-crazed Argentina, which last hosted the event in 2011, it was seen as a joyous occasion to host some of the sport’s biggest stars, including its own Lionel Messi. But calls to move the tournament, which takes place every four years, somewhere other than Argentina have mounted in recent weeks, with opponents on Twitter using the hashtag #NoALaCopaAmericaEnArgentina, and #NoToTheCopaAmericaInArgentina.

Earlier this month, Conmebol removed Colombia as a co-host of the tournament after rejecting the country’s request to postpone it amid continuing civil unrest and antigovernment protests in which dozens of people have died.

That left Conmebol to consider holding the entire championship in Argentina, amid rumors that there could be a last-minute agreement to include another host, like Chile, a vaccination success story in South America that has fully inoculated more than 40 percent of its population. Vaccinations in many other parts of the region have been lagging, prompting some wealthy and middle-class Latin Americans to seek them in the United States instead.

Daniel Politi contributed reporting.

An assembly line at a Renault-Nissan factory in Chennai, India, in 2016. Renault-Nissan, Ford India and Hyundai Motor India have suspended operations at their Chennai factories.
Arun Sankar/Agence France-Presse — Getty Images

Several top automakers have temporarily shut down plants in Chennai, known as India’s Motor City, after unions threatened to go on strike over fears of the coronavirus as the second wave of the pandemic continues to devastate the country.

Renault-Nissan, Ford India and Hyundai Motor India, which are among more than a dozen major automakers in Chennai, cited the pandemic in suspending their factory operations, according to Indian media reports. The companies did not immediately respond to requests for comment.

India’s seven-day average of known new infections has plummeted by about half since it peaked early this month at almost 400,000 a day, though experts point out that the official numbers are likely significant undercounts.

On Sunday, the government reported more than 165,000 new cases, but the southern state of Tamil Nadu, of which Chennai is the capital, remains a hot spot, reporting almost 30,000 new cases a day on average.

The Tamil Nadu government has ordered automakers to vaccinate all of their workers within a month. But companies have complained of vaccine shortages, a problem that has also plagued state vaccine rollouts. Only 3 percent of India’s nearly 1.4 billion people are fully vaccinated, according the Our World in Data project at the University of Oxford.

A nationwide lockdown last spring set off an exodus of migrant workers from cities to their home villages, and sank India into recession. Though the second wave has been far deadlier, the government of Prime Minister Narendra Modi chose not to impose another lockdown. Instead, big cities including the capital, New Delhi, and the financial centers Mumbai and Chennai imposed lockdowns themselves. Dozens of smaller cities and towns followed suit.

In Tamil Nadu, continuous process industries, including auto factories, resumed operations late this month. Factories and construction activity are also set to resume in Delhi starting Tuesday as the first phase of a gradual lifting of the citywide lockdown.

To avoid repeating last year’s migrant crisis, core infrastructure projects across the country, which employ millions of migrant workers, were exempted from lockdown rules. Projects along more than 15,000 miles of India’s highways, along with rail and city metro improvements, have continued.

The Modi government has also drawn criticism by continuing a nearly $2.7 billion redevelopment of government offices, the parliament building and the prime minister’s residence, as New Delhi reels from a surge in cases that have overwhelmed hospitals, left patients dying in the streets and kept funeral pyres burning into the night.

The uninterrupted construction activity has cushioned the blow to India’s economy, though possibly at a steep cost in human life. Thousands of workers have recently contracted Covid-19 and many have died, according to the Economic Times newspaper. The Indian government has not made much mortality data public, but its official recorded death toll of more than 320,000 is, like its figures on cases, widely considered to be a vast undercount.

Ben Goldsmith, 15, receiving the Pfizer vaccine in New York City this month. The biggest U.S. vaccination gains in recent weeks have been made among 12- to 15-year-olds.
Michelle V. Agins/The New York Times

While the pace of vaccinations in the United States has slowed, the nation is getting closer to the July 4 benchmark set by President Biden as it makes progress inoculating adolescents and those living in underserved communities.

The biggest gains in recent weeks have been made in vaccinating 12- to 15-year-olds, who became eligible for shots earlier this month, according to a New York Times analysis of data. And there has been progress in reaching some groups, including Latinos and people without college degrees, with the highest rates of vaccine hesitancy, according to the Kaiser Foundation.

All of these factors, along with a shift in the national strategy, are keeping the United States on pace to reach Mr. Biden’s goal of having 70 percent of the adult population get at least one shot by July 4. So far, 62 percent of adult Americans are there.

Vaccinated Americans have been encouraged to enjoy a summer that would have seemed unlikely last year. Americans are flying at rates not seen in about a year, many with plans to mingle among large crowds at parades and barbecues this Memorial Day weekend, the usual start of the summer in the United States.

People who are on the fence about getting a shot are more likely to get one if it is as easy as walking into a local pharmacy without an appointment, said Dr. Taison Bell, a critical care and infectious disease physician at the University of Virginia. Shifting resources away from the mass vaccination sites at stadiums to mobile clinics is starting to pay off, he said.

“The folks who were wait and see have seen the positive benefits,” Dr. Bell said, as their friends and family restart activities many put on hold for nearly a year. Even if they don’t believe in vaccines they don’t want to miss out, he said. “People are a lot more motivated.”

About 166.4 million people have received at least one dose of a Covid-19 vaccine, according to the Centers for Disease Control and Prevention. The pace, though, has slowed to about 1.5 million doses per day on average, half of the 3.38 million shots that were reported on April 13.

In April, after the rate of vaccinations peaked, Mr. Biden announced plans to target resources at places with lower immunization rates, including underserved rural areas and communities of color.

And as demand for vaccines slowed, Mr. Biden made the distribution and use of the vaccine more flexible. A national stockpile was created that could send doses where they were most needed. Pharmacies could accommodate walk-ins without appointments, and shots could be obtained at local doctor’s offices and mobile clinics. Community leaders were enlisted to reach out to the vaccine hesitant.

There has been some success with efforts to reach predominantly Black and brown communities. Nearly 50 percent of vaccinations administered through the pharmacy program have gone to people of color in the last few weeks.

In New York City, where more than 60 percent of adults have had at least one shot, the city is targeting Black and Latino residents, whose vaccination rates are about half the general population’s. Health officials are asking community groups to go door to door to reach unvaccinated people, and the city has also hired companies to promote vaccination in mostly Black and Hispanic neighborhoods.

Mr. Biden worked with Uber and Lyft, the two biggest U.S. ride-sharing services, to help jump-start the slowing vaccination rate in mid-May. The companies are offering free rides to vaccination sites until July 4.

In several states — including California, Colorado, Maryland, Ohio and Oregongovernors have dangled incentives in the form of lotteries that include cash prizes, scholarships and gift cards to keep the momentum going.

The incentives are a way “that moves the needles” for people who are waiting to get vaccinated, Dr. Bell said.

“I applaud them for being creative,” he said. “It eschews these false notions that we can’t appeal to people’s purse to make a good decision.”

A hospital staffer walking through the hall of the cardiovascular I.C.U. at Houston Methodist Hospital last year.
Erin Schaff/The New York Times

Staff members at a Houston-area hospital are suing their employer over a workplace requirement that they be vaccinated against Covid-19.

The suit names 117 Houston Methodist Hospital staff members. Their lawyer, Jared Woodfill, said the decision to mandate vaccines was “about profit, not people.”

“Methodist Hospital is forcing its employees to be human ‘guinea pigs’ as a condition for continued employment,” reads the suit, which was filed in Montgomery County on Friday.

Houston Methodist Hospital has told employees they have until June 7 to get their shots or get an exemption, according to Mr. Woodfill.

The hospital’s chief executive, Dr. Marc Boom, said in a statement that nearly all of Houston Methodist’s 26,000 employees had met the requirements for the vaccination mandate. “We are extremely proud of our employees for doing the right thing and protecting our patients from this deadly virus,” Dr. Boom said, adding, “It is unfortunate that the few remaining employees who refuse to get vaccinated and put our patients first are responding in this way.”

The Equal Employment Opportunity Commission recently released guidelines saying that employers in the country could legally require vaccination so long as they made accommodations for people unable to get the shot because of medical reasons or religious beliefs. Though it’s unclear if that guideline applies to this case, it likely makes the legal basis less clear, experts said.

The lawsuit claims that the vaccine rules violate the Nuremberg Code, a set of ethics rules that bans forced medical experiments. It dates back to World War II and was implemented in response to medical atrocities committed by Nazis.

“That argument is problematic,” said Valerie Gutmann Koch of the University of Houston Law Center. “There is nothing about a hospital’s mandatory vaccination policy that violates any human subject research rules in this country.”

She added, “Generally, hospitals have been allowed and have been mandating vaccination of their employees throughout history. We haven’t really seen this be an issue in the past.”

Some who object to vaccine requirements say they would first like to see the vaccines get full approval from the Food and Drug Administration in addition to the current emergency use authorization. Pfizer and BioNTech are seeking the full approval.

A February survey by the law firm Fisher Phillips found that just 9 percent of the more than 700 employers surveyed said they were considering mandating vaccines.

The tensions are playing out in other states as well. Employees have brought lawsuits over Covid vaccines in New Mexico and California. Some state governors banned certain vaccine requirements.

“Reasonable accommodations are required for religion and for disability,” said Henry T. Greeley of Stanford Law School. He added that for those who get exemptions, “reasonable is not necessarily fun and easy — it’s getting tested once a week, it’s being masked more often. It’s doing uncomfortable and annoying things.”

Women receiving Johnson & Johnson’s Covid-19 vaccine at Grand Central Station in New York this month.
James Estrin/The New York Times

Last month, as the Food and Drug Administration paused use of Johnson & Johnson’s Covid-19 vaccine to evaluate the risk of blood clots in women under 50, many scientists noted that clots associated with birth control pills were much more common.

The comparison was intended to reassure women of the vaccine’s safety. Instead, it has stoked anger in some quarters — not about the pause, but about the fact that most contraceptives available to women are hundreds of times riskier, and yet safer alternatives are not in sight.

The clots linked to the vaccine were a dangerous type in the brain, while birth control pills increase the chances of a blood clot in the leg or lung — a point quickly noted by many experts. But the distinction made little difference to some women.

The torrent of fury online was familiar to experts in women’s health.

“They should be angry — women’s health just does not get equal attention,” said Dr. Eve Feinberg, a reproductive endocrinologist and infertility specialist at Northwestern University. “There’s a huge sex bias in all of medicine.”

Kelly Tyrrell, an endurance athlete and communications professional in Madison, Wis., was 37 when doctors discovered potentially fatal blood clots in her lungs. She had been taking birth control pills for 25 years and experienced pain in her leg, tightness in her chest and finally extreme shortness of breath, but none of the doctors made a connection.

When a lung scan revealed multiple clots, “I instantly burst into tears,” Ms. Tyrrell recalled.

The doctors put her on a course of blood thinners — and told her never to touch estrogen again. Ms. Tyrrell switched to a copper IUD. Over time, she added, the incident had escalated into a sharp rage that was renewed by the Johnson & Johnson news.

“Part of my anger was that a medication that I took to control my fertility ended up threatening my mortality,” she said. “I’m angry that I hadn’t been counseled better about that risk, or even what to look for.”

Soldiers disinfecting outside a hospital this month in Hanoi, Vietnam.
Luong Thai Linh/EPA, via Shutterstock

Vietnam, which is coping with its worst outbreak of the coronavirus pandemic, announced new restrictions for its largest city on Sunday, a day after its health minister said a “very dangerous” new variant of the coronavirus had been detected in the country.

New social distancing requirements will be imposed in Ho Chi Minh City, which used to be known as Saigon and has a population of some nine million, roughly double that of the capital, Hanoi. The restrictions include a limit of five people in public gatherings, the state-run newspaper Tuoi Tre reported. A church in Ho Chi Minh City is at the center of a cluster involving at least 126 cases, according to state news media.

City officials said that residents should maintain strict social distancing of at least six feet and stay home unless absolutely necessary, especially if they are over 60, Tuoi Tre reported. It said the restrictions would go into effect at midnight.

Until recently, Vietnam, a country of about 97 million people, had had remarkable success in containing the virus. Last year, it never reported more than 50 new cases in a single day. By the end of April, it had reported fewer than 3,000 cases and only 35 deaths.

But since then, its caseload has more than doubled, to nearly 7,000, and its death toll has risen to 47. The coronavirus has now spread to at least 30 of the country’s municipalities and provinces.

Vietnam’s discovery of a new variant was reported at a government meeting Saturday by the health minister, Nguyen Thanh Long. He said it had traits of the variants first identified in India and Britain, according to Reuters, which obtained a recording of the meeting.

“That the new one is an Indian variant with mutations that originally belong to the U.K. variant is very dangerous,” Mr. Long said. He said laboratory tests indicated that the variant replicated itself very rapidly, which he said could potentially explain the surge of cases in Vietnam.

But it was not immediately clear how much was understood about the variant — whether it replicates as rapidly in normal conditions as it does in the lab, which specific mutations it has and how prevalent it might be. Viruses mutate constantly, but most of the mutations dwindle away. Mr. Long said the government would publish data about it soon.

Before Sunday, Vietnam had already imposed a wide range of restrictions in areas where outbreaks had occurred, including closing restaurants, bars, clubs, parks and spas. It also imposed a nationwide ban on religious gatherings.

Other Southeast Asian countries are also battling their worst outbreaks of the pandemic, including Cambodia, Thailand and Malaysia, which on Saturday reported its fifth consecutive daily record of new cases with more than 9,000. Taiwan, another success story from last year, is also suffering its worst outbreak.

All five governments are trying to step up their vaccination efforts. Health experts have said that the slow pace of inoculation in much of the world poses the risk that new variants that are deadlier and more easily transmitted will continue to emerge.

Chau Doan contributed reporting.

This decommissioned World War II submarine base in Lorient, France, is now a vaccination center.
Andia/Universal Images Group via Getty Images

Like many European countries, France had a slow start to its vaccination drive. But as it has gotten better at getting shots in arms, it is administering inoculations in unexpected places.

Disneyland Paris. The national stadium. And a decommissioned World War II submarine base in the western city of Lorient, where almost 60,000 shots have been given.

In K2, one of the three large blocks of the Kéroman Submarine Base, tents and chairs have been set up for patients and medical staff between the concrete walls of a windowless room that covers more than 9,500 square feet.

Over the past 80 years, the base has had many lives. A military installation until 1997, it has since served as a concert venue, a filming location and a site for sailing and other leisure activities. It is now a neighborhood of its own, complete with bars and restaurants.

The structure was built in 1941 after France surrendered to Germany and was one of five Atlantic Coast bases used to launch German U-boats. Lorient was nearly destroyed under Allied bombardment in 1943, but the base was almost unscathed.

“It is a pretty dark symbol in our history,” said Lorient’s mayor, Fabrice Loher.

To convert the base to a vaccination center, officials revamped the heating system to reduce the spread of the virus and added an art exhibit to give people something to look at while waiting for their shots.

The center delivered more than 6,000 doses over the past week. As coronavirus cases decline in France, which has seen about 5.7 million total cases and more than 100,000 deaths, more than 15 percent of the population has been fully vaccinated.

Among the first to receive a shot at the former submarine base was a Frenchman, now in his 90s, who was conscripted by the Germans during the war to repair and work on the reassembly of submarines, said Jean-Michel Pasquet, the chief of the vaccination center. It was the first time the man had been back to the base since the war, Mr. Pasquet said.

“He told us it was a beautiful symbol of resilience,” Mr. Pasquet said. “This bunker that used to build warships to kill people now embodies a comeback to life.”

Protesters gathered outside Hatwrks in Nashville on Saturday after the store advertised Star of David “Not Vaccinated” patches.
Laura Thompson/Shutterstock

Protesters gathered on Saturday outside a hat store in Nashville that sold “not vaccinated” Star of David patches and compared vaccine passports to the Nazi practice of requesting “your papers.”

The store, Hatwrks, said on Instagram in a post that was later deleted that it was selling the patches for $5. Amid an outbreak of anti-Semitic attacks across the country, the post was criticized on social media and outside the store, where protesters held signs saying “no Nazis in Nashville” and “sell hats not hate.”

A separate post to the store’s Instagram account — which also touted “mask free shopping” and promoted the conspiracy theory that vaccines have microchips in them — said that “all unvaccinated people will be segregated from society, marked and must wear a mask. What comes next?”

The hat company Stetson said that “as a result of the offensive content and opinions shared by Hatwrks,” it would stop selling its products through the store. Several other hat companies also announced they would immediately end distribution with the retailer, including Goorin Bros, Dorfman Pacific, Milano Hat Company, Akubra, Bailey and Kangol.

Brixton stated the company had not sold its product to the store in years and requested that its name be removed from the store’s website.

A post on the store’s account responding to the criticism said that “I pay much more respect to history by standing up with the fallen than offering silence and compliance.” A later post apologized “for any insensitivity,” saying “my hope was to share my genuine concern and fear, and to do all that I can to make sure that nothing” like the Holocaust “ever happens again.”

Gigi Gaskins, who according to state records is the store’s owner, did not respond to requests for comment.

Criticism of vaccine passports, or digital proof of Covid-19 vaccination, extends beyond the United States: In London and Brussels on Saturday, demonstrators gathered to protest vaccination requirements.

Oregon said last week that it would require businesses to verify the vaccination status of customers before allowing them to enter without a mask, though business groups there questioned the practicality of the requirement. New York has created the Excelsior Pass, but is not requiring that it be used widely.

In Tennessee, Gov. Bill Lee, a Republican, signed into law on Wednesday legislation prohibiting local governments from requiring businesses to verify proof of vaccination.

U.S. Experts See Urgent Need for New Search of Pandemic’s Origins 1
Andrew Rae

A little more than a year ago, The New York Times created a new section in the Sunday paper in response to the sudden and drastic changes to our domestic lives brought about by the pandemic. The first issue of At Home landed on readers’ doorsteps just a couple of weeks later, on April 26, 2020.

Today, after 57 weekly installments, we are publishing the final issue of the At Home print section.

Now, the world is changing again, perhaps not as swiftly as it did after March 11 of last year, when it felt as if a metal gate fell, forever dividing time into “before” and “after.” But restrictions on travel are being loosened, masks for many people are becoming a thing of the past, more children are in some form of in-person school and, most important, more than 166 million Americans have been at least partially vaccinated against the coronavirus.

So we’ve chosen this moment on the cusp of a summer that we hope will be filled with delightfully ordinary joys, to bow off the stage. The Times will continue to offer advice both online and in other print sections, but readers will not find At Home in their Sunday paper. And that’s a good thing. It’s another sign that the journey back to “normal” is underway.

Tourists in the coastal resort town of Cascais this month. Portugal opened up to British tourists last weekend despite still adhering to coronavirus precautions such as curfews.
Daniel Rodrigues for The New York Times

After enduring a winter of strict lockdown, and a gradual reopening in spring marred by lousy weather, the first British tourists have begun arriving in Portugal after the country was “green-listed” by Britain for quarantine-free travel.

The arrivals offer a preview of what a broader return to international travel might look like for others, including vaccinated Americans when they are welcomed to Europe this summer: a mixture of joy, relief, and at times awkward interactions as cultures converge after a year of disparate pandemic experiences.

This month, Britain included Portugal on its “green list” of 12 countries and territories that residents could travel to starting May 17 without quarantining for up to 10 days upon return. Now, Portugal is one of Britain’s only tourist destinations. Most other green-listed places are either not accepting tourists or are not major draws.

But British travelers expecting a kind of prepandemic travel experience found something different in Lisbon during the first weekend it reopened to them. Though the Portuguese capital still offered its signature food, museums, picturesque vistas and attractions, stringent mask rules and curfews reminded visitors this would not be an unfettered escape.

Mark Boulle, 38, from Oxford, England, said he typically tries to avoid crowds while traveling, so the trip was in that respect a dream. When he took a day trip on Monday to Sintra, a nearby town with postcard-ready palaces and castles, “for the first half of the day I virtually had the whole place to myself,” he said.

But masking — or not — is proving to be a source of tension for both visitors and the Portuguese. Mr. Boulle was dismayed by the widespread use of masks outdoors in Lisbon, given that, in Britain, the government has never suggested wearing masks outside and most people do not.