A drive-through testing site in Los Angeles last month. California is one of several states that had appeared to have gained control of the virus, only to see it spread rapidly throughout the fall.
Credit…Bryan Denton for The New York Times

California’s intensive care units could be overloaded by the middle of December, and its hospitals could be dangerously close to full by Christmas, according to sobering projections that Gov. Gavin Newsom presented on Monday.

And the strain could be even worse in the hardest-hit areas, like the San Joaquin Valley, which was projected to reach 83 percent of its hospital capacity by Dec. 24.

“If these trends continue, California will need to take drastic action,” Mr. Newsom said during a virtual briefing, adding that more severe restrictions, including full stay-at-home orders, could come within the next few days.

California is one of several states that had appeared to have gained control of the virus, only to see it spread rapidly throughout the fall. On Sunday it became the first state to record over 100,000 cases in just a week, according to a New York Times database.

A University of Arizona Covid-19 modeling team recently urged the state of Arizona to take action to stem hospitalizations or else “risk a catastrophe on a scale of the worst natural disaster the state has ever experienced.”

And in New York, Gov. Andrew M. Cuomo said the state will take a series of emergency actions as it faces a new “nightmare of overwhelmed hospitals.”

Already, 99 percent of California’s residents are under a curfew that bans them from leaving their homes to gather or to go to nonessential businesses after 10 p.m. Los Angeles County health leaders have gone even further, announcing a ban on all gatherings in public or at private homes that goes into effect on Monday.

The surge has upended some marquee elements of California’s sports and entertainment scenes. The San Francisco 49ers will play their next two home games in Glendale, Ariz., after health officials in Santa Clara County, Calif., where the team’s stadium is, banned contact sports at all levels through late December in a bid to slow the surge in virus infections there. The U.C.L.A. men’s basketball team announced that its home opener, scheduled for Monday, was being postponed because of its opponent’s virus protocol.

In Los Angeles, residents complained on Monday that a feature film shoot that had been permitted by the city and county’s official film office had shut down a coronavirus testing kiosk at Union Station for a day. City officials said that residents who had testing appointments for Tuesday would be accommodated at any of the city’s other testing locations.

Officials had spent the weekend talking with local leaders and health care providers about their concerns, said Dr. Mark Ghaly, the state’s secretary of health and human services, who also spoke during the Monday briefing.

“Everything is on the table, in terms of how we guide the state through this,” he said. “And we want to make sure what we do is impactful and as time-limited as possible.”

But unlike early in the pandemic, when just a few coastal states bore the brunt, the governor noted that the tidal wave of cases slamming the entire country has limited the likelihood of aid from the federal government or other states.

The total number of coronavirus cases in the United States for November surpassed four million on Saturday, more than double the record set in October of 1.9 million cases. And the sharp escalation is likely to continue after Americans traveled by the millions for the long Thanksgiving weekend. Over 96,000 are hospitalized with Covid-19, a record, according to the Covid Tracking Project.

By contrast, after three weeks of lockdown in England, the number of new cases has fallen 30 percent, according to new data. And after strict measures throughout Europe, a drop in new cases there helped drive down newly reported cases globally for the first time since September, according to Dr. Tedros Adhanom Ghebreyesus, the director general of the World Health Organization.

Mr. Newsom emphasized that California will be able to build on work that the state began earlier this year, including a registry of retired or otherwise nonpracticing health care workers who would be willing to return to work. Eleven surge health care facilities could be prepared quickly to receive patients.

“We don’t anticipate this,” the governor said, referring to the alarming hospitalization figures. “I want folks to know we intend to bend this proverbial curve.”

Dr. Scott Atlas resigned his position on the White House coronavirus task force on Monday.
Credit…Anna Moneymaker for The New York Times

Dr. Scott W. Atlas, the former Stanford University radiologist who espoused disputed theories and rankled government scientists while advising President Trump on the pandemic, has resigned his White House position, according to a senior government official.

The move was not entirely unexpected. Dr. Atlas caught Mr. Trump’s eye with his frequent appearances on the Fox News Channel over the summer, and joined the White House in August as a special government employee for a limited term that was set to expire this week. Fox News first reported his resignation, which Dr. Atlas later announced on Twitter.

“I worked hard with a singular focus — to save lives and help Americans through this pandemic,” Dr. Atlas wrote in a letter obtained by Fox, adding that he “always relied on the latest science and evidence, without any political consideration or influence.”

But some of Dr. Atlas’s administration colleagues would likely differ with that assessment, citing views that differ starkly from those put forth by officials at the Centers for Disease Control and Prevention and other government scientists. Dr. Atlas has argued, for example, that the science of mask wearing is uncertain and that children cannot pass on the coronavirus.

Even more controversial was his libertarian vision of the role of the government in the pandemic. In Dr. Atlas’s view, the government’s job was not to stamp out the virus but simply to protect its most vulnerable citizens as Covid-19 takes its course.

His argument was that most people infected with the virus would not get seriously ill, and at some point, enough people will have antibodies from Covid-19 to deprive the virus of carriers — “herd immunity.” Public health experts were appalled, and Dr. Atlas clashed in particular with Dr. Anthony S. Fauci, the government’s top infectious disease specialist, and Dr. Deborah L. Birx, the coronavirus response coordinator.

“I don’t want to say anything against Dr. Atlas as a person, but I totally disagree with the stand he takes. I just do, period,” Dr. Fauci said earlier this month on the NBC program “Today.”

But Dr. Atlas had the ear of one person who mattered: Mr. Trump.

Video player loading
Gov. Andrew M. Cuomo of New York announced on Monday a series of emergency measures to combat rising hospitalizations and coronavirus case numbers.CreditCredit…Mike Groll/Office of Governor Andrew M. Cuomo, via Associated Press

As he warned that New York State had entered a new phase in fighting the spread of coronavirus, Gov. Andrew M. Cuomo announced on Monday a new series of emergency measures to combat rising hospitalizations and case numbers statewide.

Among other steps, Mr. Cuomo urged hospitals to form plans in case of staff shortages, develop emergency field protocols and prepare to add 50 percent of bed capacity. In Erie County in Western New York, all elective surgeries will be stopped on Friday and similar protocols could be enacted in other areas of the state.

“It’s a new phase in the war against Covid,” Mr. Cuomo said at a news conference in Manhattan. “It’s a war in terms of preparation and mobilization.”

Mr. Cuomo said that the strength of the virus’s second wave has forced the state to rely less on test positivity rates as the determinant for restrictions, and focus more on hospital capacity. On Monday, the governor announced that hospitalizations topped 3,500 over the weekend, a level not seen since May. The governor also raised the possibility that a “critical hospitalization situation” could trigger a regional return of the most stringent measures enacted in the spring, which led to the closure of all nonessential businesses statewide.

“We are not going to live through the nightmare of overwhelmed hospitals again,” he said. “If a hospital does get overwhelmed, there will be a state investigation.”

Mr. Cuomo has warned that the holidays and indoor social gatherings during the winter season could trigger a further resurgence of the virus, a concern shared in neighboring New Jersey. Gov. Philip D. Murphy said Monday that the state will limit all outdoor gatherings to 25 people in an attempt to stem an ongoing surge of cases — and an expected spike after the Thanksgiving holiday.

The new limit on outdoor gatherings, which takes effect on Dec. 7, will sharply reduce the permitted number of people from 150. Religious and political gatherings will be exempt, as will funerals, memorial services and wedding ceremonies, Mr. Murphy said at a news conference.

New Jersey will also suspend all indoor youth and adult sports, including practices and competitions, starting Saturday and extending through Jan. 2. College and professional sports will be exempt from the ban, which Mr. Murphy said he hoped would only be temporary.

Despite rising rates of positive test results, Mr. Cuomo has resisted implementing the kind of widespread shutdowns seen in March, when hundreds of New Yorkers began to die every week, and much of New York’s economic activity ground to a complete halt.

Rather, Mr. Cuomo’s strategy has been to utilize targeted restrictions on individual areas — known as his “micro-cluster initiative” — which has now expanded to nearly 30 locations around the state, including in all five boroughs of New York City, its suburban counties, and major upstate population centers.

On Monday, he said new statistics — including hospitalization rates, death rates and available hospital beds — would be used to determine lockdown levels under the state’s color-coded restriction system. The state will evaluate how virus metrics change following Thanksgiving — the effects of which could be delayed because the incubation period for the virus is up to 14 days — before deciding how those restrictions would be determined, he added.

Hospital networks across the state should also better prepare for a surge in patients than they did in the spring, and plan to spread out patients between individual sites, Mr. Cuomo said. The hope is to avoid an overwhelming number of patients at any one site, as happened in the spring at hospitals at the center of the pandemic in New York City. “That has always been my nightmare,” he said, referring to Elmhurst Hospital Center in Queens, where beds were filled in March and refrigerated trucks sat outside to hold the dead.

As virus cases continue to rise across the county, hospitals have also begun to face crisis-level shortages of staff in addition to beds. Mr. Cuomo said on Monday that he was “very worried” about those potential issues in New York, urging hospitals to identify retired nurses and doctors in case of a need. “We can build beds, we can’t create more staff,” he said.

He added that further increasing and better distributing testing across the state, as well as establishing ongoing testing in schools with a focus on elementary school, middle school and special education students at all levels were also top priorities.

Still, the governor was hopeful that the situation in New York was “manageable” and said the state was better prepared than in the spring to curb the spread of the virus.

“I think we’re going to be fine here on all of this,” Mr. Cuomo said. “But we have our work cut out for us. You can’t just sit by and let this happen.”

New York City health workers staffed a coronavirus testing station at Penn Station on Monday to screen arriving travelers and inform them about quarantine regulations.
Credit…James Estrin/The New York Times

Did Thanksgiving gatherings and travel accelerate the spread of the coronavirus in the United States, as many experts had feared? When will we be able to tell?

Those questions do not yet have clear-cut answers, but one thing is certain: The daily figures over the next few days won’t prove anything. It takes time for infections to take hold, time for tests to detect them, and time for results to be reported.

In interviews, four experts agreed that there probably will be an upward bump in cases linked to the holiday, similar to the rises that were seen after Memorial Day and July 4. But they had different estimates for when it would emerge.

Part of the uncertainty stems from the virus itself. Its incubation period — the time after a person catches it but before symptoms appear — can range from two days to two weeks or longer, though five days seems to be typical.

People who suspect infection may then wait to be tested, and test results may take days to come back from a lab.

Dr. Thomas Russo, a professor of medicine at the University at Buffalo, said that taking those factors into account, he expects a holiday bump to become noticeable at the end of this week, and continue through much or all of next week.

“Most people were being good and had celebrations just within their own households,” he said. “But that significant minority that did not is driving this surge, and will be our undoing.”

He noted that around 97 percent of infected people who develop symptoms do so within 12 days after exposure — and will already have been contagious for a day or two.

Others will feel no symptoms at all, an added complication that has dogged public health officials since the pandemic began. Those people may not quarantine or be tested — but they can infect others, lengthening the chain of transmission.

That’s what happened after July 4, said Megan L. Ranney, an emergency physician and public health researcher at Brown University. She said a jump in positive tests began between two and four weeks after the holiday, suggesting that many were pass-along infections.

The American Automobile Association forecast that about 50 million people would travel for Thanksgiving. Even if only 1 percent caught the virus, Dr. Ranney said, “that’s an extra 500,000 infections in one day,” and they could infect untold thousands more before showing up in the statistics. “We are looking at an exponential effect,” she said, one that would only truly be seen around Christmas and New Year’s Eve. “It will be a double whammy.”

Lewis S. Nelson, chair of the Department of Emergency Medicine at Rutgers New Jersey Medical School, said he was not certain that Thanksgiving travel and gatherings would create a widespread surge in new cases. The virus has been tricky, he said, and predicting the numbers can be extremely difficult.

“We keep saying we’ll see a bump, but most of these events don’t seem to really materialize into something really concerning,” Dr. Nelson said. “Sometimes what you expect to happen doesn’t happen.”

Even so, he said, “my gut tells me we should remain concerned and attentive.”

Dr. Nelson said his hospital in Newark, N.J., was overwhelmed in April, but is manageable now, even though the state is reporting many more new cases. He said there were currently about 30 coronavirus patients, compared to more than 200 in April, a drop he and his colleagues were still puzzling over.

“Just the whole fact that we are not experiencing April right now is inexplicable at this point,” he said. “People haven’t changed. A lot of us believe maybe the virus has.”

Officials were trying to make sure that any Thanksgiving exposure would be reflected in the data. On Monday, Mayor Bill de Blasio of New York City urged residents who had ignored official guidance and attended Thanksgiving gatherings to get tested.

In anticipation of a renewed demand, the city has opened 25 new testing locations in the last week. It will also now post online the wait times at its testing sites, which had seen growing lines as New Yorkers scrambled to get tested before their holiday plans.

The city’s seven-day average positive test rate was at 4.03 percent, Mr. de Blasio said, but he warned that the data may be skewed because fewer tests were conducted during Thanksgiving weekend.

Similar issues are clouding daily statistics across the country, as some states held off reporting for some or all of the holiday weekend and then caught up with big batches of new reports. Experts warned against drawing too many conclusions from the daily figures until states get back to a normal reporting rhythm.

The Moderna headquarters in Cambridge, Mass.
Credit…Cody O’Loughlin for The New York Times

As the drugmaker Moderna said it applied to the Food and Drug Administration on Monday to authorize its coronavirus vaccine for emergency use, the health secretary Alex M. Azar II reiterated that distribution would begin quickly after the expected approvals of the Moderna and Pfizer vaccines vaccine.

“We could be seeing both of these vaccines out and getting into people’s arms before Christmas,” he said on “CBS This Morning” on Monday.

If its vaccine is approved, Moderna said that injections for Americans could begin as early as Dec. 21. The company also announced highly encouraging results, saying that complete data from a large study show its coronavirus vaccine to be 94.1 percent effective, a finding that confirms earlier estimates.

Stéphane Bancel, the company’s chief executive, said in an interview that it was “on track” to produce 20 million doses by the end of December, and from 500 million to a billion in 2021. Each person requires two doses, administered a month apart, so 20 million doses will be enough for 10 million people.

Asked about the role of states in the distribution process, Mr. Azar said that doses would be shipped out through normal vaccine distribution systems, and governors would be “like air traffic controllers” determining which hospitals or pharmacies receive shipments. While governors will determine which groups are prioritized, he said he hoped that they would follow the federal recommendations.

The first shots of the two vaccines are likely to go to certain groups, including health care workers; essential workers like police officers; people in other critical industries; and employees and residents in nursing homes. More than 100,000 Covid deaths have occurred in U.S. nursing homes and other long-term care centers.

On Tuesday, a panel of advisers to the Centers for Disease Control and Prevention will meet to determine how to allocate initial supplies of vaccine.

Mr. Azar said that C.D.C. experts will base their recommendations on the latest data on virus cases around the country.

But generally, “Be thinking people in nursing homes, the most vulnerable, be thinking health care workers who are on the front lines,” he said.

Even though some of the largest outbreaks have occurred in the nation’s prisons, the C.D.C. advisory committee has prioritized correctional officers and others who work in jails and prisons — but not inmates.

Now several groups, including the American Medical Association, are calling for coronavirus vaccines to be given to inmates and employees at prisons, jails and detention centers, citing the unique risks to people in confinement — and the potential for outbreaks to spread from correctional centers, straining community hospitals.

In Kentucky, Gov. Andy Beshear said Monday that 26,000 residents and employees of nursing homes and other long-term care facilities would be the first in his state to get vaccinated against the coronavirus, along with 12,000 of the state’s more than 200,000 health care workers.

Moderna is the second vaccine maker to apply for emergency use authorization; Pfizer submitted its application on Nov. 20. Pfizer has said it can produce up to 50 million doses this year, with about half going to the United States. Its vaccine also requires two doses per person.

The hopeful news arrives at a particularly grim moment in the U.S. health crisis. Coronavirus cases have surged and overwhelmed hospitals in some regions, and health officials have warned that the numbers may grow even worse in the coming weeks because of travel and gatherings for Thanksgiving.

The new data from Moderna show that its study of 30,000 people has met the scientific criteria needed to determine whether the vaccine works. The findings from the full set of data match an analysis of interim data released on Nov. 16 that found the vaccine to be 94.5 percent effective. It also showed that the vaccine was 100 percent effective at preventing severe disease from the coronavirus.

More than 70 vaccines are being developed around the world, including 11 that, like Pfizer’s and Moderna’s vaccines, are in large-scale trials to gauge effectiveness.

More than 1,400 inmates and staff at San Quentin State Prison in California were infected with the coronavirus last summer in one of the largest outbreaks in the country.
Credit…Justin Sullivan/Getty Images

With coronavirus vaccine distribution expected to start as early as this month, public health officials are scrambling to develop guidelines for the equitable allocation of limited supplies. The Advisory Committee on Immunization Practices of the Centers for Disease Control and Prevention will meet on Tuesday to make initial determinations about who gets the first shots.

There is broad consensus that health care workers who treat Covid-19 patients should be first in line. Other high-priority groups include residents and employees of long-term care facilities, essential workers whose jobs keep people fed and society running, and medically vulnerable and older adults — roughly in that order.

Prison inmates are not ranked in the top tiers, however, even though some of the largest outbreaks have occurred in the nation’s prisons. Instead, the C.D.C. advisory committee has prioritized correctional officers and others who work in jails and prisons for the first phase of immunizations — but not inmates. The federal prison system will set aside its initial allotment for such employees, according to documents obtained by The Associated Press.

Now several groups, including the American Medical Association, are calling for coronavirus vaccines to be given to inmates and employees at prisons, jails and detention centers, citing the unique risks to people in confinement — and the potential for outbreaks to spread from correctional centers, straining community hospitals.

“We aren’t saying that prisoners should be treated any better than anybody else, but they shouldn’t be treated any worse than anybody else who is forced to live in a congregate setting,” said Dr. Eric Toner, co-author of a report on vaccine allocation published by the Johns Hopkins Center for Health Security.

There is also a powerful public health argument to be made for prison vaccination: Outbreaks that start in prisons and jails may spread to the surrounding community. “Prisons are incubators of infectious disease,” Dr. Toner said.

“It’s a fundamental tenet of public health to try and stop epidemics at their source,” he added.

A nurse in Oregon who mocked the state’s pandemic protocols in a video that circulated on TikTok has been placed on administrative leave, her employer said.

The video shows the nurse, Ashley Grames, wearing scrubs and a stethoscope around her neck, with a caption saying that she does not wear a mask in public, arranges play dates for her children and still travels.

Ms. Grames is an employee at Salem Health, which operates Salem Health Hospital in Salem, Ore., and other medical facilities treating Covid-19 patients in the state. Oregon has had at least 74,120 cases and 907 deaths since the beginning of the pandemic, according to a New York Times database.

Salem Health said in a statement posted on Facebook that members of the public had alerted the company to the video, which it said showed “cavalier disregard for the seriousness of this pandemic.” Ms. Grames has been “been placed on administrative leave pending an investigation,” the health system said.

The Facebook post has attracted more than 1,000 comments, including from people who said they had relatives in the hospital. “Is there a law in Oregon that medical professionals must wear a mask while being off the clock and off hospital grounds?” one reader wrote, adding that the video was “very irresponsible and shows zero compassion for people who have experienced covid.”

Salem Health said in its statement that it required its staff members, patients and visitors to follow guidance from the Centers for Disease Control and Prevention around hand washing, social distancing and wearing masks that cover the mouth and nose when around others.

“The Covid pandemic is serious and requires a serious response,” the company said in its statement. “And at Salem Health we are very serious about our approach to Covid.”

The president of the International Federation of Red Cross and Red Crescent Societies, Francesco Rocca, high levels of mistrust of health authorities “clearly facilitated transmission of the virus at all levels.”
Credit…Giannis Papanikos/Associated Press

The head of the International Federation of Red Cross and Red Crescent Societies, Francesco Rocca, warned on Monday that misinformation and mistrust could hinder efforts to distribute a coronavirus vaccine around the world, even as countries scramble to secure doses for their populations.

Speaking at a virtual news conference ahead of a United Nations meeting on the virus this week, Mr. Rocca argued that since the start of the pandemic, high levels of mistrust of health authorities “clearly facilitated transmission of the virus at all levels.”

For example, many people refused to wear face masks or practice social distancing.

The same dynamics could create a disaster if vaccine distribution is not handled properly, he said. The challenge is compounded by growing hesitancy about vaccines in general.

For that reason, Mr. Rocca said, his organization shared the widespread sense of relief and optimism that has come with the progress in vaccine development , but with “a dose of caution.”

“To beat this pandemic, we also have to defeat the parallel pandemic of distrust,” he said.

Mr. Rocca also called for greater efforts to ensure the equitable distribution of vaccines around the world — and criticized the “vaccine nationalism” of wealthy countries that bought up massive quantities of vaccines in exclusive deals with pharmaceutical companies. He called on all governments — including the incoming administration of President-elect Joseph R. Biden Jr. — to join a global immunization effort known as Covax.

“I would like to repeat here our urgent warning to all governments: None of us are safe until all of us are safe,” he said.

The San Francisco 49ers celebrated a road win Sunday over the Los Angeles Rams. The 49ers will use the Arizona Cardinals’ stadium for their remaining home games because Santa Clara County has shut down their stadium as a measure against coronavirus spread.
Credit…Kyusung Gong/Associated Press

The San Francisco 49ers will play their next two home games in Glendale, Ariz., the team announced in a statement on Monday. The relocation came after health officials in Santa Clara County, Calif., where the team’s stadium is, banned contact sports at all levels through late December in a bid to slow the surge in coronavirus infections there.

The team will play its games in Week 13 and 14 in State Farm Stadium, the home of the Arizona Cardinals, which was able to accommodate the move because the teams’ schedules do not conflict. The 49ers (5-6) will play against the Buffalo Bills (8-3) on Dec. 7 and face the Washington Football Team (4-7) on Dec. 13, but the club still has not determined where they will practice and live during that time.

“Very appreciative of Arizona welcoming us during these unprecedented times,” 49ers team owner Jed York wrote on Twitter, thanking the Cardinals team owner Michael Bidwill.

While local and state guidelines for controlling the spread of the virus have prevented spectators from attending some N.F.L. games in other markets this season, this is the first time local health protocols have prevented a team from playing games or practicing in its home market.

This summer, health officials in Santa Clara were among the first to ban fans at N.F.L. games and passed an ordinance requiring players and coaches to wear masks at all times, months before the league took the same step last week.

On Saturday, Santa Clara County took new measures intended to reduce the rate of infections, including mandatory 14-day quarantining of people who travel there from more than 150 miles away, as cases in the area rose to a new high last week and its positive cases per 100,000 people to climbed to 26.8.

The number of infections per 100,000 residents in Maricopa County, Ariz., site of the Cardinals’ stadium, is 48.6, nearly twice as high as in Santa Clara County.

Andrej Plenkovic, the prime minister of Croatia, center, taking part in a commemoration march in Vukovar, Croatia, this month.
Credit…Associated Press

Andrej Plenkovic, the prime minister of Croatia, has tested positive for Covid-19 days after his government abandoned some of the most lax pandemic measures on the continent and introduced strict rules meant to curb the virus’s spread, as patients inundated hospitals.

Plenkovic is home and feels well, according to a statement on the government’s website, attributed to a spokesman. The prime minister entered self-isolation on Saturday after his wife tested positive for Covid. He led Monday’s government session from his attic, according to a spokesman.

Croatia has experienced a surge in new infections since late October, with 21,457 active cases and 1,786 deaths in the country of four million. Croatia contained the pandemic this spring by introducing some of the strictest measures in Europe, including a broad lockdown and travel limits. Those same restrictions were abandoned in time for Croatia’s economically vital summer tourism season, and did not return this fall to combat a second wave.

Until last week, Croatia’s measures were some of the most lax on the continent, amounting to limits on gatherings, mask-wearing and social distancing suggestions, as well some curtailed business hours. The prime minister even took part in a memorial walk in Vukovar on Nov. 18 with over 1,000 others. The town is now experiencing a spike in new infections.

The government pushed back against requests that the country adopt tougher measures in the face of an increase in new infections, shying away from the lockdowns and curfews used by other European Union members. Plenkovic frequently said such moves were “not an option.” His ministers repeatedly chastised the public for the increase in new infections, claiming that only responsible behavior could stop the virus’s spread.

Croatia’s government relented last week, after reports from hospitals of dwindling capacity and overworked staffs. On Friday, it introduced greater limits on gatherings and public transport, and shut gyms, bars and restaurants. On Monday, it presented a package of laws that includes fines for anyone violating the new restrictions, and financial aid for struggling businesses.

Five ministers in the Croatian government have contracted Covid since the second wave of the pandemic hit Croatia in late October, including Vili Beros, the health minister.

Michael Reagan, 50, of New York, had a moderate illness from coronavirus, but his neurological symptoms post-recovery are serious and alarming, including seizures, trembling of hands and fingers, loss of sense of direction, and loss of short-term memory.
Credit…Hiroko Masuike/The New York Times

One of the coronavirus’s most unexpected tricks is its ability to cause neurological symptoms, including dizziness, headaches and the blunting of taste and smell. Traces of the virus have shown up in brain tissue, examined post-mortem, but scientists don’t know exactly how the virus got there, much less how it might alter neurons’ function.

A new study, based on autopsies of people who died of Covid-19, provides some of the first clues. The virus may spread to the brain through the nose, where it can invade nerve endings deep in the nasal passages. If further tissue analysis is supportive, the findings should help explain how the virus reaches circuits in the brain that support perception, balance and mental acuity.

In the paper, posted Monday by the journal Nature Neuroscience, a research team based in Berlin produced the first images of intact coronaviruses in the so-called nasopharynx, where the throat meets the nasal cavity, and where odor receptors and perceptual cells converge.

The virus can enter the nervous system “by exploiting the close vicinity of olfactory mucosal, endothelial and nervous tissue, including delicate olfactory and sensory nerve endings” in the mucous layer of the nasopharynx, the authors conclude.

Up to a third of people who fall ill from Covid-19 report at least one neurological deficit, whether in taste, smell, balance or alertness. These symptoms are often transitory, but they are common enough to suggest that people with severe forms of the disease should show some evidence of infection in their central nervous systems.

In the new report, a research team led by Dr. Helena Radbruch and Dr. Frank Heppner, neuropathologists at the Charité-Universitätsmedizin, in Berlin, studied tissue samples from 33 people who had died after contracting Covid-19. The samples came from four areas of the brain, and from the olfactory mucosa, the mucous membrane of the nasopharynx.

The analysis found evidence of the virus in various parts of the brain, and in the olfactory mucosa, where its concentration was highest. Deep in this layer, near nerve endings that project to the brain, the researchers found the coronavirus’s signature spike protein, which it uses to attach to and infect cells.

Taken together, the findings suggest that the virus is “able to use the olfactory mucosa as a port of entry into the brain,” said Dr. Heppner, in a prepared statement.

The authors cautioned that their findings apply only to people with severe disease, and not necessarily to the majority of people infected, who experience modest symptoms, if any.

GLOBAL ROUNDUP

A Christmas tree was illuminated as the traditional Christmas market had been cancelled at the Old Town Square in Prague on Saturday.
Credit…David W Cerny/Reuters

The traditional Christmas markets that dot European cities, drawing thousands of festive revelers into plazas to enjoy mulled wine, colorful lights and public art, have largely been canceled this year.

But on Advent Sunday, the official start of the holiday season, celebrations continued in different forms. In partially locked-down Bratislava, the capital of Slovakia, the mayor, Matus Vallo, led viewers of a Facebook livestream on a walk through the city’s historic center.

Wearing a cheerful Christmas sweater, Mr. Vallo met musicians and artists along the way, received soothing words from a local priest, eyed winter-themed paintings from art galleries and lit up a Christmas tree in the main square.

“We know what the situation is, but we decided that we won’t let Advent be ruined anyway,” he said to the camera.

Locals and visitors in Bratislava will still be able to gawk at the Christmas lights on a stroll, but officials wanted to avoid the large holiday crowds. Moving traditional events online was part of that effort; a series of holiday concerts and events will be streamed throughout December.

It’s just one of several creative solutions as markets were canceled across the continent. In Landshut, Germany, visitors must experience the Christmas markets as a drive-through, according to Agence France-Presse. They can observe the spectacle from inside their cars as mask-wearing employees hand them menus offering typical treats like roasted chestnuts and gingerbread hearts.

And in the United States, New York City will limit visitors to the Christmas tree at Rockefeller Center, in a bid to fight the holiday crowds that usually pack the surrounding plazas and sidewalks. The city will keep the viewing time to 5 minutes, Mayor Bill de Blasio said. Groups will be limited to four people.

The mayor also said that a “reservation system” would be in place. Later, Tishman Speyer, the real estate firm that controls Rockefeller Center, said it would use a “virtual queueing” system to manage long lines, rather than advanced timed ticketing.

Still, the mayor, who has expressed concern that cases of the virus could surge during the holiday, encouraged people to watch the annual tree-lighting ceremony — scheduled for Wednesday — at home instead of flocking to Midtown Manhattan. “Please, if you can make a decision to watch it on TV, that’s so much better,” he said.

  • Hong Kong will limit gatherings in public to two people, including two per table at restaurants, as it battles a surge in cases. Playgrounds, swimming pools and karaoke rooms will close, while gyms will remain open but be limited to two mask-wearing participants, the city’s chief executive, Carrie Lam, said at a news conference on Monday. Hong Kong has reported an average of 85 new daily cases in the past week, far above the near-zero tallies it had reported after a summer surge.

  • President-elect Joseph R. Biden Jr. spoke with United Nations Secretary-General António Guterres on Monday about “the need for a strengthened partnership” between the U.S. and the U.N. on global issues, a statement from Mr. Biden’s transition team said, including combating the pandemic and “building resilience to future public health challenges.”

  • Italy approved a stimulus package worth $9.6 billion, or 8 billion euros, on Sunday to support struggling businesses. The deal will postpone or suspend tax deadlines for some businesses, subsidize amateur sports associations and send checks of 1,000 euros to seasonal workers in the tourism, spa and entertainment industries. Italy is currently under a nationwide 10 p.m. curfew with bars and restaurants closing at 6 p.m., and some regions have further restrictions.

  • In Russia, a hospital near Moscow reported on Monday that it had administered the first known batch of the Russian-made Sputnik V vaccine to civilians. The Domodedovo Central City Hospital confirmed in a phone interview that the vaccine had been delivered and that the first shipment available for general use had already run out. Russia’s government backed efforts to develop a vaccine before other countries has been widely criticized for cutting corners. The rush to deliver a vaccine to the general public has also been spurred by the growing number of new cases and deaths in the country, with the total number of cases in Russia nearing 2.3 million.

  • Serbia will receive 20 doses of Russia’s Sputnik V vaccine to begin laboratory testing, Prime Minister Ana Brnabic said on Monday, adding that Serbia would consider joint production of the vaccine. The country is also in talks with Pfizer about purchasing its vaccine.

  • Vietnam said on Monday it had its first locally transmitted case in 89 days, prompting contact tracing efforts and stricter screening. The 32-year-old man’s infection was linked to a flight attendant who tested positive after returning from Japan, Reuters reported. The country has largely staved off the virus, reporting only 1,346 cases throughout the pandemic.

A full lockdown has been ordered for the weekends only. During the week, a partial lockdown will require people to stay home from 9 p.m. to 5 a.m.
Credit…Associated Press

Turkey is imposing its strictest lockdown since the outbreak of the pandemic, as the country’s total number of cases surpassed half a million, according to government figures released on Monday.

Starting Tuesday night, everyone will be required to stay home from 9 p.m. to 5 a.m. on weekdays and around the clock on weekends, from Friday evening to Monday morning, President Recep Tayyip Erdogan announced.

The hybrid approach is intended to keep the labor force working in an already staggering economy while limiting the spread of the virus as much as possible.

People older than 65 or younger than 20 will be barred from using public transportation. They are already under restrictions that allow them out of their homes for just three hours a day.

Mr. Erdogan also asked people not to allow guests in their homes, and banned large gatherings in private residences for New Year’s celebrations, religious ceremonies or condolence calls.

Funerals and wedding ceremonies will be limited to 30 people. Traditional Turkish baths, saunas, massage parlors and swimming pools will be closed.

Turkey, which only recently began reporting complete data on confirmed cases, has been averaging nearly 23,000 new cases a day over the last two weeks, according to a New York Times database.

Kim Jong-un met with government officials on Sunday, seen in this photo provided by the North Korean government.
Credit…Korean Central News Agency/Korea News Service, via Associated Press

North Korea’s leader Kim Jong-un “harshly criticized” his government agencies for mishandling the economy, the country’s state media reported on Monday, as new data revealed just how much the pandemic had slashed the country’s already dwindling trade with China.

Signs had already emerged earlier this month that North Korea’s economic trouble was deepening, driven by long-standing international sanctions and the impact of the pandemic. According to customs data released by Beijing last week, North Korea’s imports from China from January to October plummeted by 76 percent to $487 million, while its exports shrank 74 percent to $45 million in the same period.

​China is North Korea’s only major trading partner, accounting for more than 90 percent of its external trade. In October, the North’s import from China amounted to a mere $253,000, nearly a 99-percent drop from the previous month. South Korean officials and analysts have warned that a sharp decline in imports from China in recent months could drive up domestic prices in the North.

The Chinese government only ​records official trade and does not cover smuggling that takes place across the borders​ between the two neighbors​. Still, the figures provide​d​ fresh evidence that the coronavirus was squeezing the North Korean economy more effectively than international sanctions ever have.

During a meeting of the Workers’ Party that Mr. Kim presided over on Sunday, the government agencies responsible for the economy w​ere harshly criticized for “failing to provide scientific guidance” and “failing to overcome subjectivism and formalism in their work,” the North’s official Korean Central News Agency reported.

But this was not the first time Mr. Kim has admitted to his country’s deepening economic woes, acknowledging in August that his five-year plan for economic growth had failed. Mr. Kim all but sealed North Korea’s borders with China​ earlier this year over fears of the potentially catastrophic consequences the pandemic could inflict on the country’s poor health system.

North Korea insists that it has registered no coronavirus cases, but outside experts remain skeptical.

Those We’ve Lost

Iris Meda, 70, a retired nurse, wanted to help in the fight against the coronavirus, so she began teaching nursing skills to high school students. But she came down with Covid-19 and died on Nov. 14.
Credit…Selene Meda-Schlamel

Iris Meda, 70, didn’t feel right sitting on the sidelines when the pandemic hit. She’d been retired only a few months, and still had a lifetime of nursing experience in hospitals, prisons, schools and long-term care facilities to share.

So she went back to work in August, teaching nursing skills to high school students through Collin College, north of Dallas. But within weeks, she had come down with Covid-19 herself. After nearly a month in the hospital, most of it on a ventilator, she died on Nov. 14.

Her daughter, Selene Meda-Schlamel, said her mother was exposed to the virus on Oct. 2 while teaching a laboratory class, despite the precautions she was taking.

“I wasn’t worried, because I knew she was wearing an N95, and that she was some distance from the students,” Ms. Meda-Schlamel recalled, in an interview.

“I said to myself, ‘If something happens to her, it happens to her doing something she loves, fulfilling her calling and benefiting the world,’” she said. “But that’s a very different outlook from, ‘My best friend is gone, my kids don’t have a grandmother. Everything that we planned on doing will never occur.’”

Ms. Meda grew up in New York, the oldest of nine siblings, and was a natural caretaker from childhood, her daughter said. She married at 20, expecting to be a stay-at-home mother, but at her husband’s urging, she went back to school and earned a nursing degree from City College.

“She had a very personal touch,” Ms. Meda-Schlamel said. “You never felt like she was rushing you.”

Ms. Meda worked as a nurse at the jail on Rikers Island before moving to Texas in 1993, where she spent the rest of her career before retiring in January. When she took up teaching, she wanted to pass along to her students the kind of encouragement she had gotten to pursue an education. After class, she often returned home “lit up” from the thrill she got from teaching, her daughter said.

When her Covid-19 symptoms worsened in mid-October and she began struggling to breathe, Ms. Meda called her daughter for a ride to the hospital. Ms. Meda-Schlamel recalled that in the car, her mother handed her an envelope containing her medical documents and a handwritten card that she forgot about in the hectic days that followed.

When she finally opened it, she said, she found a note her mother had written after their phone call, telling her how proud she was of her and what a wonderful life she had before her. And two signed checks fell out, meant to help her daughter cover the hospital bills. On one, the amount was left blank.

“That was kind of symbolic of how she was as a person,” Ms. Meda-Schlamel said. “She was always giving people blank checks, blank emotional checks: ‘Whatever you need from me, if I have it, I’ll provide it.’”

People walk past closed shops on London’s normally bustling Oxford Street earlier this month.
Credit…Andrew Testa for The New York Times

By the end of the third week of England’s second national lockdown, which began early this month in a bid to stem a second wave of coronavirus infections, the number of new cases has fallen 30 percent, according to new data.

Some parts of northern England, which had been hit particularly hard by the new outbreak, experienced an even greater drop, the latest interim findings from Imperial College London’s React study showed.

But Matt Hancock, the British health secretary, warned that the data, while promising, showed the country could not “take our foot off the pedal just yet,” according to the BBC. In a post on Twitter late Sunday, Mr. Hancock cautioned that “we mustn’t waste our progress now we can see light at the end of the tunnel” with mass testing and promising coronavirus vaccine candidates on the horizon.

England’s current lockdown is set to end just after midnight Wednesday. But the lifting of restrictions will be different across the country, as regions move into one of three tiers based on their current rate of infection. Britain is still grappling with the highest number of Covid-19 deaths in Europe and its deepest recession on record, with experts warning that the knock-on effects of the pandemic could last for years.

A volunteer receiving the Oxford coronavirus vaccine. Misinformation about vaccines has been spreading, often by accident, on TikTok. So those who know better are making TikTok videos that try to spread the facts.
Credit…Andrew Testa for The New York Times

While some in the creative community on TikTok joke about the coronavirus vaccine or tease people who are part of the anti-vaccine movement, scientists and coronavirus vaccine participants are hoping to be a source to fight misinformation on the app.

In February, a scientist who goes by Dr. Noc on TikTok started noticing a need for science-based videos about the coronavirus that his expertise in working to develop an antibody treatment for Covid-19 could help provide.

He has since posted many videos addressing the coronavirus, including updates on vaccines, mink infected with the coronavirus and how some people with the virus can lose their sense of taste and smell. The videos, he said, have left him vulnerable to harassment from people against vaccines and masks.

Lately, Dr. Noc has found himself answering questions reflecting the fears and misconceptions about coronavirus vaccines that are sometimes perpetuated on the platform by jokes about side effects or forays into fictional narrative, like a sci-fi scenario in which the government kills those who refuse a vaccine.

“While people may appreciate them, they’re not going to go viral,” he said about his videos. “It’s a game of catch-up.”

So, no, nanoparticles can’t send people’s biometric data to a cloud, as he has posted, and no, mRNA can’t change people’s D.N.A.

Vaccine trial participants have also been describing their experiences and answering questions about the process for viewers.

Ashley Locke, 29, from Nashville, said she posted about her experience as a participant in AstraZeneca’s trial to document a journey in her life, but didn’t expect the more than two million views it has gotten, or the thousands of questions and comments.

Since that post, she’s been creating videos and answering questions from her comment section about side effects and wearing masks after being a part of the trial. She even brought in a friend, also a part of a trial, to talk.

But with all that, she said, she isn’t always successful in demystifying the vaccine.

“There are some people that are really out there that are convinced that it’s a microchip,” she said. “They’re a little too far gone to convince.”

The University of Sydney. The Australian education sector is set to lose billions of dollars if the country’s borders do not reopen before the end of 2021.
Credit…Paul Miller/Australian Associated Press, via Associated Press

A cohort of 63 international students on Monday arrived in Australia under a pilot program that allows them to resume their studies, even as the country’s borders remain closed because of the pandemic.

The students, the first group of international students allowed in since March, arrived at Darwin International Airport in the Northern Territory from Singapore. They are from mainland China, Hong Kong, Japan, Vietnam and Indonesia.

All of them tested negative for the coronavirus 72 hours before boarding the charter flight. They will be required to quarantine at a former workers’ camp outside the city of Darwin for 14 days before being allowed to re-enter the campus at Charles Darwin University.

The education sector, crucial to the Australian economy, is set to lose billions of dollars if the country’s borders do not reopen before the end of 2021. According to research from Victoria University, the loss of international students is also affecting the makeup of Australia’s cities.

In September, Charles Darwin University made a deal with the state and the federal government that would enable students to return from overseas to study. The success of the program could influence whether more international students can return to study in other states, including South Australia and the Australian Capital Territory.

Speaking to the local news media, the students — some of who had become stranded while visiting family overseas — said they felt lucky to return to Australia, which is beginning to reopen as states eliminate, or come close to eliminating, the spread of the coronavirus.

Xitao Jiang, a 23-year-old student from China returning to Australia, told the Australian Broadcasting Corporation on Sunday that was “very lucky” to have the opportunity to return to the country and study at the university in Darwin.