More Countries Impose U.K. Travel Restrictions Amid Concern Over Virus Mutation


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People wait to depart from St. Pancras train station in London. On Saturday, Prime Minister Boris Johnson of Britain imposed a lockdown in London and southeast England, citing a fast-spreading coronavirus variant.CreditCredit…Stefan Rousseau/Press Association, via Associated Press

Countries across Europe and beyond began closing their borders to travelers from the United Kingdom on Sunday, and the European Union set up a crisis management meeting, a day after Britain’s prime minister, Boris Johnson, ordered a wholesale lockdown on London and surrounding areas, citing concerns of a new fast-spreading variant of the coronavirus.

Train stations in London on Saturday night filled with crowds of people scrambling to leave the city to escape the new restrictions, which went into effect at midnight and effectively quarantined the capital and other areas from the rest of the country, the harshest measures to be taken since the country’s first lockdown in March.

On Sunday, Britain’s health secretary, Matt Hancock, called those who packed trains “clearly irresponsible.” He also said that the restrictions Mr. Johnson imposed could be in place for months.

The first wave of countries to bar travelers from the United Kingdom were in Europe. The Netherlands said it would suspend flights from Britain from Sunday until Jan. 1, noting that the variant found in England was “ thought to spread more easily and more quickly.”

Italy also suspended air travel, and Belgian officials on Sunday enacted a 24-hour ban on arrivals from the United Kingdom by air or train, which could be extended. Germany and Switzerland announced bans on travel between their countries and both Britain and South Africa, where a similarly contagious version of the virus has emerged. Austria, Ireland, France and Bulgaria also announced bans. Portugal, which banned travel to and from the United Kingdom, is making exceptions for Portuguese nationals or residents. And Canada said on Sunday that it would ban all flights from the U.K. for 72 hours, beginning at midnight.

In the United States, Gov. Andrew M. Cuomo of New York urged the federal government to take action, saying that “right now, this variant in the U.K. is getting on a plane and flying to J.F.K.,” while also acknowledging that it may be too late. The State Department said that its travel advisory to Britain had not been changed and remained at Level 3.

Spain asked the European Union for a coordinated response, and senior officials from the bloc’s 27 member states met by video conference Sunday evening to share their plans. They agreed to decide on any coordinated action at the crisis management meeting, to be held Monday morning.

Within hours, more countries took action. Iran suspended flights to Britain for two weeks, Reuters reported. Israel barred foreign nationals not only from the United Kingdom, but also from South Africa and Denmark, where a coronavirus mutation that occurred in mink was transmitted back into the human population. Turkey temporarily suspended flights from those three countries, as well as the Netherlands, Reuters said.

Transportation officials in England said that they would increase the number of police officers monitoring hubs like railway stations to ensure only essential journeys were being taken. And during one of the year’s biggest shipping periods, the effects were sure to be seen at Britain’s ports. The Port of Dover, one of the world’s busiest, where thousands of trucks travel each day, closed its ferry terminal to “all accompanied traffic.” Traffic had reached a fever pitch as companies stockpiled goods before new post-Brexit customs rules went into effect.

Viral mutations are not uncommon, and British officials said this variant had been detected in a handful of other countries. The estimate of greater transmissibility for the British variant is based on modeling and has not been confirmed by lab experiments, said Muge Cevik, an infectious disease expert at the University of St. Andrews in Scotland and a scientific adviser to the British government.

“Over all, I think we need to have a little bit more experimental data,” she said. “We can’t entirely rule out the fact that some of this transmissibility data might be related to human behavior.”

The virus lockdown came as another down-to-the-wire drama was playing out for Britons: the trade negotiations between Britain and the European Union. Critics say the British prime minister’s penchant for last-minute decisions has complicated the handling of the coronavirus crisis and narrowed the window for scrutiny of any trade deal with the E.U.

Dana Rubinstein and Raphael Minder contributed reporting.

United States › United StatesOn Dec. 20 14-day change
New cases 179,801 +10%
New deaths 1,422 +19%

World › WorldOn Dec. 20 14-day change
New cases 536,080 +4%
New deaths 7,561 +5%

Where cases per capita are

David Spicer prepares to conduct a coronavirus test on the first day of operation of a testing site adjacent to Terminal 1 of Manchester Airport in England earlier this month.
Credit…Oli Scarff/Agence France-Presse — Getty Images

Scientists say they are concerned but not surprised by variants in the coronavirus like the one that prompted officials in Britain to sound an urgent alarm on Saturday, declaring that a highly contagious new version of the virus had begun circulating in England.

That announcement resonated worldwide: Shortly afterward, a number of countries, including the Netherlands and Germany, banned travel from Britain. The new variant represents a rare event; it carries more than a dozen unique mutations, many more than its predecessors, and its swift emergence is not likely to be a matter of luck alone. It has displaced competing variants that have been circulating for months in southern parts of the country — a crowded field, unlike early in the pandemic.

A preliminary analysis of the variant, by members of the Covid-19 U.K. Genomics Consortium, carried enormous weight. When the U.K. consortium flags a variant, others start searching their own data; already, officials in Italy have reported one new case of the British variant, with no evidence of community spread so far. There, the patient and his partner returned to Rome’s Fiumicino airport from the United Kingdom in recent days, according to the health ministry. Other countries will most likely turn up similar samples.

But the coronavirus is a continual shape-shifter, like all viruses. And given the worldwide spread of the virus, rare events like this one were bound to happen, experts said. In a cautionary note, a separate panel of British scientists expressed only “moderate confidence” that the newly identified variant was more transmissible.

Still, scientists are continually watching for mutations that enhance the virus. One concern is that the vaccination of millions of people and growing immunity in human populations may exert enormous pressure on the virus to evolve so-called escape mutations that evade the immune response, setting back the global fight by years.

Several experts urged calm, saying it would take years, not months, for the virus to evolve enough to render the current vaccines impotent.

“No one should worry that there is going to be a single catastrophic mutation that suddenly renders all immunity and antibodies useless,” said Jesse Bloom, an evolutionary biologist at the Fred Hutchinson Cancer Research Center in Seattle.

“It is going to be a process that occurs over the time scale of multiple years and requires the accumulation of multiple viral mutations,” he added. “It’s not going to be like an on-off switch.”

In South Africa, where a similar variant has been found, scientists were also quick to note that human behavior was driving the epidemic, not mutations whose effect on transmissibility has yet to be quantified.

Escape from immunity requires that a virus accumulate a series of mutations, each allowing the pathogen to erode the effectiveness of the body’s defenses. Some viruses, like influenza, amass those changes relatively quickly. But others, like the measles virus, collect hardly any of the alterations.

Immunizing about 60 percent of a population within about a year, and keeping the number of cases down while that happens, will help minimize the chances of the virus mutating significantly, said Emma Hodcroft, a molecular epidemiologist at the University of Bern in Switzerland.

Emma Bubola contributed reporting.

Loraine Hopkins Pepe, director of nursing education, administered the Pfizer-BioNTech vaccine to Dr. Richard Fine, head of anesthesiology at Einstein Medical Center in Philadelphia on Wednesday.
Credit…Hannah Yoon for The New York Times

A panel advising the Centers for Disease Control and Prevention voted Sunday to recommend that people 75 and older be next in line to receive the Covid-19 vaccine in the United States, along with about 30 million “frontline essential workers,” including emergency responders, teachers and grocery store employees.

The decision, a compromise aimed at getting the vaccine to the most vulnerable of two high-risk groups, came as the debate over who should receive the vaccine first grew increasingly urgent. Some 128,000 shots have been administered in the first five days of the U.S. vaccine campaign, mostly to health care workers.

Groups of essential workers, such as construction and food service workers, the committee said, would be eligible for the next wave. Panel members clarified that local organizations had great flexibility to make those determinations.

“I feel very strongly we do need to have that balance of saving lives and keeping our infrastructure in place,” said Dr. Helen Talbot, a member of the panel and an infectious-disease specialist at Vanderbilt University.

Together, the two groups the committee voted to prioritize on Sunday number about 51 million people; federal health officials have estimated that there should be enough vaccine supply to inoculate all of them before the end of February. The vote was 13 to 1.

In addition to teachers, firefighters and police, a subgroup of the committee suggested that “frontline essential workers” should include school support staff; day care, corrections personnel, public transit, grocery store and postal workers; and those in working in food production and manufacturing. But the group’s official recommendation is not that specific.

A registered nurse, Stacy Delaney, working with vials of vaccine at Temple University Hospital in Philadelphia on Wednesday.
Credit…Hannah Yoon for The New York Times

After days of confusion about the uneven pace of vaccine distribution in the United States, a top official involved in the effort said on Sunday said that an administrative snafu was responsible for states being unable to order the number of doses promised to them for the coming week.

At least 14 states complained this week that they had access to far fewer doses than expected, and that the shortage disrupted their plans to distribute the vaccines from Moderna and Pfizer, which have received emergency approval from the Food and Drug Administration.

On Sunday, Dr. Moncef Slaoui, the scientific adviser for Operation Warp Speed, the Trump administration’s effort to get coronavirus vaccines to Americans, explained the problems as an administrative holdup, saying that the initial distribution plan had neglected to take into account last-minute F.D.A. requirements.

“We all made the error or mistake of assuming the vaccine that’s actually produced and being released is already available for shipment, when in fact there’s a two-day’s lag between the time at which we generate a lot of data that shows this vaccine vial is actually safe and right, and the time we can ship it,” Dr. Slaoui said on CNN’s “State of the Union.”

His comments clarified an apology made on Saturday by Gen. Gustave F. Perna, the chief operating officer of Operation Warp Speed, who claimed responsibility for the issues, citing uncertainties about the numbers of doses manufacturers were prepared to ship and coordination with the F.D.A.

The F.D.A. must receive “certain documentations” after approval and before the drugs can be shipped, Dr. Slaoui said, “and that has resulted in differences between what was in the plan and what was actually done.”

He said the mistake had been corrected, and that on Monday the government would ship 5.9 million doses of the Moderna vaccine and another 2 million of the Pfizer vaccine.

State officials and governors expressed frustration in recent days after learning they could access only a portion of what they had been promised — 40 percent less, in the case of California. Dr. Slaoui and Dr. Scott Gottlieb, the former F.D.A. commissioner and a board member of Pfizer, said that there were no problems with the vaccines themselves or the supply.

States were given estimates in mid-November for how many doses they would be receiving in the first rounds of distribution. But those numbers were just a prediction, according to an administration official who was not authorized to speak on the record, and those predictions were not intended to be understood as official figures.

When the government realized that the actual number of doses ready for distribution was lower than predicted, it applied the reduction to every state proportionally. But the number of doses each state has been officially allocated has not changed, the official said.

On MSNBC on Sunday, Gov. Gretchen Whitmer, Democrat of Michigan, who had been vocal about the miscommunication last week, said she appreciated General Perna’s apologies.

“We’re ready for a lot more vaccines,” she said. “What I need is consistent, reliable information so that we can live up to the promise of getting as many vaccines into people’s arms as quickly as possible and save lives.”




Congress Reaches Deal on $900 Billion Coronavirus Relief Plan

Senator Mitch McConnell, the majority leader, said on Sunday evening the stimulus package would include direct payments for Americans.

More help is on the way. Moments ago, in consultation with our committees, the four leaders of the Senate and the House finalized an agreement. It will be another major rescue package for the American people. As our citizens continue battling this coronavirus this holiday season, they will not be fighting alone. We’ve agreed to a package of nearly $900 billion. It is packed with targeted policies that help struggling Americans who have already waited entirely too long. For workers at the hardest-hit small businesses, there will be a targeted second draw of the Paycheck Protection Program. We’ve not worked so hard to save as many jobs as possible all these months only to fumble the ball with vaccinations already underway. Speaking of vaccines, we can nullify the success of Operation Warp Speed by falling asleep at the switch on distribution, so this agreement will provide huge sums for the logistics that will get these lifesaving shots to our citizens as fast as possible. Of course, many millions of Americans have lost their jobs and are continuing to lose them through no fault of their own. This package will renew and extend a number of the additional important federal unemployment benefits that have helped families stay afloat. Across all kinds of families, in all kinds of situations, this has been a difficult time across the board. So at the particular request and emphasis of President Trump and his administration, our agreement will provide another round of direct-impact payments to help households make ends meet and continue our economic recovery.

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Senator Mitch McConnell, the majority leader, said on Sunday evening the stimulus package would include direct payments for Americans.CreditCredit…Stefani Reynolds for The New York Times

WASHINGTON — Congressional leaders said they had reached agreement on Sunday on a $900 billion stimulus package that would provide direct payments and jobless aid to struggling Americans and badly needed funds for small businesses, hospitals, schools and vaccine distribution, overcoming months of stalemate on a measure intended to boost the pandemic-battered economy.

The agreement, struck after a renewed flurry of talks broke a partisan logjam that had persisted since the summer, came hours before the federal government was set to run out of funds. Once drafted, it was expected to be merged with a sweeping catchall spending measure that would keep the government funded for the remainder of the fiscal year, creating a $2.3 trillion behemoth whose passage will be Congress’s last major act before adjourning for the year.

Senator Mitch McConnell of Kentucky, the majority leader, announced the agreement Sunday evening on the Senate floor, declaring, “We can finally report what our nation has needed to hear for a very long time: More help is on the way.”

With additional time needed to transform their agreement into legislative text, both chambers were expected later Sunday to approve a one-day stopgap spending bill — their third such temporary extension the last 10 days — to avoid a government shutdown while they were finalizing the deal.

The House could vote as early as Monday on the final spending package, and the Senate was expected to follow shortly afterward, sending it to President Trump for his signature.

While the text was not immediately available, the agreement was expected to provide stimulus payments of $600 to American adults and children and revive supplemental federal unemployment benefits at $300 per week — half the level of aid delivered by the $2.2 trillion stimulus law enacted in March, as the coronavirus pandemic’s devastating health and economic impact was just coming into focus.

It also would extend two federal unemployment programs that expanded and extended regular benefits, and would have lapsed next week without action by Congress. The agreement includes rental and food assistance, as well as billions of dollars for schools and small businesses, reviving the Paycheck Protection Program, a federal loan program that lapsed this year.

While the deal marked a triumphant moment in talks that had long been stalled, it was far narrower than the one Democrats had long insisted upon, and nearly twice the size of the one Republicans had said they could ever accept. Democrats had refused for months to scale back their demands for a multitrillion-dollar package, citing the devastating toll of the virus, and Republicans dug in against another large infusion of federal aid, pointing to the growing deficit.

But in the end, the crucial breakthrough came just before midnight on Saturday, when Republicans dropped an effort to ban the Federal Reserve from establishing certain emergency lending programs to help stabilize the economy in the future.

Mr. McConnell said the two parties were still finalizing text as of dinnertime in Washington, and he did not indicate when they would formally introduce a bill or bring it up for a vote.

“I’m hopeful we can do this as promptly as possible,” Mr. McConnell said.

Migrant workers stood in front of the closed shrimp market in Samut Sakhon Province, Thailand, on Sunday.
Credit…Athit Perawongmetha/Reuters

Thailand, normally one of the most visited places on Earth, had seemed to have all but eradicated local transmission by tightening its borders and engaging in rigorous contact tracing.

But on Sunday, health authorities announced the country’s biggest outbreak to date: 689 infections, linked to a single shrimp market not far from Bangkok, the Thai capital.

A two-week lockdown has been ordered in Samut Sakhon, the coastal province where the market is located, with migrant workers barred from leaving and most stores closed except for food takeout.

But cases connected to the market are now appearing all over the country, and fears are growing that the virus has already spread widely. The first case linked to the shrimp market was confirmed just a week ago.

Much of Thailand’s seafood industry is powered by low-paid undocumented workers from neighboring Myanmar, where Covid-19 is spreading rapidly. Although officials claim that the border between the two countries is almost fully sealed, migrants have continued to slip across the frontier.

Thailand has so far kept its confirmed caseload to around 5,000 cases and 60 deaths, and mask-wearing remains common in Bangkok and other big cities. Life has been relatively normal in the country for months, with schools, offices, shops and restaurants open, and there has not been a major press for testing. The new outbreak may change that.

So far, health officials said they had tested 1,443 people linked to the Samut Sakhon shrimp market, of whom 689 had tested positive, mostly migrant workers from Myanmar. Most are asymptomatic; only 32 people have been hospitalized.

In Bangkok, metropolitan officials said on Sunday that they would be testing migrant workers at 472 fresh-food markets. Dancing will be suspended in bars, and some schools will be closed until Jan. 3, and New Year’s celebrations have been called off.

Health officials counseled calm.

“The number will keep increasing, but you don’t have to worry,” said Opart Karnkawinpong, the director general of Thailand’s department of medical sciences. “The faster we move, the faster we can control it.”

A nursing home resident in Pompano Beach, Fla., receiving a vaccination on Wednesday. Florida was one of a handful of states to begin inoculating residents last week.
Credit…Joe Raedle/Getty Images

A large swath of nursing homes in the United States are poised to receive Covid-19 vaccines beginning Monday, as the country pushes to inoculate some of its most vulnerable citizens and free them from months of confinement.

Nursing homes have felt the brunt of Covid-19’s severity in the United States. At least a third of the country’s more than 305,000 deaths have been reported among residents and employees of nursing homes and other long-term care facilities for older adults, while more than 787,000 staff members and residents have become infected. Most homes have been closed to visitors since the early days of the pandemic, leaving residents feeling lonely and isolated.

Vaccinations started in the United States last week, with health-care workers at the front of the line. The effort has expanded to long-term care facilities as conditions in them have deteriorated anew, with nearly 20,000 cases and an estimated 5,000 deaths reported per week, according to the American Health Care Association and National Center for Assisted Living.

Some states, including West Virginia, Connecticut, Delaware and Florida, began administering vaccines at long-term care facilities last week. The homes are expected to remain locked down until residents’ relatives have been vaccinated.

At The Cedars, a retirement community in Portland, Maine, pharmacists from Walgreens are expected to arrive at 8:30 a.m. Monday to administer vaccines to residents and staff members. “There will be much celebration in the air,” said Katharine O’Neill, the director of operations and communications.

In New York, the state health facilities association — which includes 425 skilled nursing homes and assisted living facilities — has been working with the state and federal governments for about two months to plan how the vaccine will be administered, said Stephen Hanse, the president and chief executive of the association.

Most homes will get the vaccine through CVS Pharmacy or Walgreens, part of a deal struck with the federal government, and residents will probably be vaccinated in their rooms, while staff will receive the doses in separate spaces, Mr. Hanse said.

There will be vaccination celebrations, probably mixed in with holiday festivities. Morale is higher than it has been throughout the pandemic, Mr. Hanse said, because the vaccines give residents hope that they will soon be able to see their loved ones in person after many months of solitude. “One of the things that’s really in play here. too, especially in New York, was the inability for family and loved ones to visit with their family,” he said.

In Fairborn, Ohio, at the Wright Rehabilitation and Healthcare Center, the first doses of the vaccine are scheduled to arrive in the first week of January, Greg Nijak, the executive director of the facility, said.

Preparations have centered on securing vaccine consent forms and disseminating information about the safety of the vaccine. “

Elsewhere, there is trepidation. At the Martha T. Berry Medical Care Facility outside Detroit, a recent survey found that less than half of the staff wanted to take the vaccine. “Our staff is mostly skeptical,” Kevin Evans, the executive director of the facility, said in an email.

The facility has started an information campaign for residents and staff members. Despite the apprehension among employees, residents are eager for the vaccines’ arrival, which the facility is planning to celebrate.

“Though we have multiple FaceTime and Skype and window visits,” Mr. Evans said, “it is not the same as a hug from a son, daughter, or grandchild.”

N95 masks being decontaminated in April in Ohio. Hospitals are still short on masks and other protective gear.
Credit…Brian Kaiser for The New York Times

As Americans celebrate the rollout of a Covid-19 vaccine, many of the doctors and nurses first in line for inoculation say a victory lap is premature.

They fear that the optimism stirred by the vaccine will overshadow a crisis that has drawn scant public attention in recent months: the alarming shortage of personal protective equipment, or P.P.E., that has led frontline medical workers to ration their use of the disposable gloves, gowns and N95 respirator masks that reduce the spread of infection.

At St. Mary’s Medical Center in Duluth, Minn., health care workers who treat Covid-19 patients are required to reuse their tightfitting respirator masks up to six times before throwing them away. Although soiled N95s are sterilized each day with ultraviolet light, Chris Rubesch, 32, a cardiac nurse, says the masks invariably sag after two or three shifts, leaving gaps that can allow the virus to seep through.

“Our days are filled with fear and doubt,” Mr. Rubesch said. “It’s like driving a car without seatbelts.”

Many of the shortages are the result of skyrocketing global demand, but supply chain experts and health care providers say the Trump administration’s largely hands-off approach to the production and distribution of protective gear over the past nine months has worsened the problem. That has left states and hospitals to compete for limited supplies. Price gouging has become the norm, and scores of desperate institutions have been duped into buying counterfeit products.

President Trump has made only sparing use of the Defense Production Act, a Korean War-era law that allows federal agencies to coordinate the distribution of scarce goods and force companies to prioritize government orders. The D.P.A. can also provide grants to companies that need help ramping up production.

With the White House largely disengaged from the crisis, medical workers, supply chain specialists and public health experts are urging President-elect Joseph R. Biden Jr. to make good on his campaign promises to use the Defense Production Act to increase domestic manufacturing of personal protective equipment, test kits, vaccines and the medical supplies needed to immunize hundreds of millions of Americans. They are also hoping the incoming administration will take over the distribution of scarce goods and put an end to profiteering and the mad scramble for P.P.E. that has pitted states and deep-pocketed hospital chains against nursing homes and small rural hospitals.

New York’s largest transit union is lobbying to have its employees included in the next round of coronavirus vaccinations.
Credit…Gregg Vigliotti for The New York Times

Among state capitals, New York’s has long stood apart as a venue for favor trading and behind-the-scenes deals. Now, as the coronavirus rages and vaccines remain in short supply, the pandemic has been thrust squarely into the maw of Albany politics.

“Everyone is chasing the same thing now, and it really is remarkable,” said James E. McMahon, a veteran Albany lobbyist who represents a school bus company and other firms interested in early vaccination. “The need was there and then there’s the vaccine and all of a sudden, people are saying, ‘Oh Jesus, we’ve got to get in line now.’”

Apparently attuned to the atmosphere, Gov. Andrew M. Cuomo made several pronouncements this past week that his administration would not be swayed by interest groups.

“There will be no political favoritism,” the governor said in a news conference on Wednesday, a message he repeated on Friday.

The question of where groups of workers stand in the line for vaccines has yet to be resolved in New York or in a majority of other states, according to a review by the nonprofit Kaiser Family Foundation. The federal government is expected to issue final recommendations on who should be deemed essential soon. But it is largely up to states to prioritize vaccine distribution among those workers.

In New York, emergency responders like police officers, transit workers and those who maintain power grids and other critical infrastructure will almost certainly be part of the next wave, according to a state plan.

But the remaining uncertainty has led to clamoring for consideration in state capitols and in Washington from a wide array of businesses and workers. Tens of millions of Americans, designated as essential, continue to toil amid the pandemic’s dangers while others work from home.

The list of those who qualified as essential in New York stretched from chiropractors to landscapers to bicycle mechanics. That long list has allowed all sorts of industries to claim they should also be among the first for the vaccine.

Rich Maroko, president of the Hotel Trades Council, wrote a letter to state health officials in which he made the case for the 35,000 hotel employees the union represents in the city.

“These workers have continued to put themselves at risk and have worked throughout this pandemic performing services that are critical to the State of New York,” he wrote.

Stuart Appelbaum, the president of the Retail, Wholesale and Department Store Union, which represents 40,000 workers in New York, including grocery story workers, said he had reached out to state officials, but had yet to hear back.


In the days before Thanksgiving, infectious-disease experts and elected officials repeatedly warned Americans to limit their travel and family gatherings, fearing the holiday would turn into a nationwide super-spreader event.

But experts and data suggest what happened around the date, Nov. 26, was something like a micro-spreader, more a tornado picking its spots than a hurricane blowing down everything in its path.

Like much about the virus, exactly how much Thanksgiving gatherings spread it and why the effects seem to have varied so much from place to place remains unclear. But, with the virus surging as Christmas and New Year’s approach, epidemiologists and health officials across the country are picking apart the effects of Thanksgiving in search of lessons for the coming holidays.

Epidemiologists said coronavirus case numbers and other data show that in many parts of the country, Americans altered their routines during the holiday, staying home instead of traveling and canceling large family gatherings. But there have been regional and isolated surges that can be attributed in part to activity around those days in late November.

In California, for example, the worst days of the pandemic are hitting now, with a spike in new cases, hospitalizations and deaths that has shocked the state.

For a period last week in Los Angeles County, a coronavirus death was recorded every two hours. And infections have touched many families. On Thursday, Eric Garcetti, the mayor of Los Angeles, announced that his 9-year-old daughter had tested positive for the virus.

Cases in the region were spiking before the holiday, but the widespread transmission that occurred during Thanksgiving gatherings in Riverside, Los Angeles, Orange, Santa Barbara and other counties was contributing to the pace of spread, officials said.

The number of people hospitalized with Covid-19 in those four counties jumped 156 percent, from 3,400 to 8,687, in the three weeks from Thanksgiving to Dec. 17, according to data from the California Department of Public Health. In the three weeks preceding Thanksgiving, hospitalizations increased 108 percent.

“We had all these little fires going all throughout the county, and then someone with Thanksgiving just threw some gasoline — that’s what it kind of feels like,” said Wendy Hetherington, the chief of epidemiology for the public health department in Riverside County, where roughly one of five residents is testing positive.

Still, experts said that, in general, parts of the country that were improving pre-Thanksgiving continue to improve post-Thanksgiving, while other regions experiencing surges before the holiday continue to worsen, suggesting that any nationwide Thanksgiving effect was muted.

“The fact is, people took precautions, and those have helped to not make things worse — not enough to make things better, but enough to not make things worse,” said Ellie Murray, a professor of epidemiology at Boston University. “We probably have enough data to say that people didn’t do things completely as normal, and we are not in the worst-case scenario.”

Patients and their relatives rest on the sidewalk near Holy Family Hospital, one of the busiest government hospitals and a treatment center for Covid-19, in Rawalpindi, Pakistan.
Credit…Saiyna Bashir for The New York Times

As winter sets in, cold weather, pollution and public apathy to the coronavirus are weighing heavily on Pakistan’s limited health care system.

Pakistan’s Covid-19 positivity rate has rocketed up to about 7.7 percent of tests administered in recent weeks from only 2 percent in October, prompting a plea from health experts and doctors in Karachi for the government to impose a strict nationwide lockdown.

Despite the rise, people in Karachi show few signs of concern. Even as the positive testing rate topped 18 percent in the city of 20 million, markets were packed with shoppers not wearing masks. Buses were full. Overflow passengers rode on the roofs.

Prime Minister Imran Khan has closed schools but ruled out a second lockdown, saying it would decimate the economy.

By official figures, Pakistan is weathering the coronavirus better than the United States, Europe and neighboring India. Government restrictions on travel or the overall youth and resilience of Pakistan’s population may have contributed.

“Pakistanis remained safe during the first wave and didn’t face a serious situation like seen in other countries, mainly because of God’s special blessings,” said Dr. Qaiser Sajjad, a leader of the Pakistan Medical Association.

But the second wave is proving more lethal. Cases are surging, and limited testing compared with other countries suggests the virus could be racing through the country at an even higher rate.

Total infections have reached 448,522, according to researchers at Johns Hopkins University using official figures, and more than 9,000 people have died from the virus. Some hospitals are turning away patients. In Dr. Ruth Pfau Civil Hospital in Karachi, managers are scrambling for beds.

Health experts faulted the rising caseload on ineffective government limits on personal contact and widespread doubts — often fueled by conspiracy theories — that Covid-19 poses a threat.

A survey conducted in October by Gallup Pakistan showed that 55 percent of respondents in the country doubted that the virus was real and 46 percent believed it was a conspiracy. Those attitudes make it tougher to enforce mask-wearing and other preventive measures and could complicate the distribution of vaccines when they become widely available.