Covid-19 Vaccines, Variants and Cases: Live Updates – The New York Times

The seven-day average of daily new coronavirus tests has declined to 1.7 million from a high of 2.1 million last month.
Credit…Pete Kiehart for The New York Times

The number of coronavirus tests administered daily in the United States has been trending downward for more than two weeks. And though experts say the trend is too fresh to set off major alarm bells, the decline raises the possibility that testing has reached a ceiling at a time when scientists say the nation should be conducting millions more tests per day to help stop the spread of the virus.

On Jan. 18, the seven-day average of daily new tests reached an all-time high of more than 2.1 million, according to the Covid Tracking Project. On Thursday, it was about 1.7 million. Maintaining a level of at least 2 million tests per day is considered an important threshold by public health experts, who say that it is a level of testing that will allow them to identify most people with symptoms, as well as two people with whom each sick person has been in close contact.

This dip coincides with a downturn in another important coronavirus metric: the seven-day average of new reported coronavirus cases, which was down 57 percent Thursday compared to its peak on Jan. 8.

When the number of tests performed and cases reported go down at the same time, public health experts want to know if the dip in new cases is tied to the fact that fewer tests are being performed — the theory being that “If you don’t test, you don’t find cases,” as Dr. Jodie Guest, an epidemiologist at Emory University, put it recently.

For now it seems the number of new cases is indeed falling, said Dr. Ashish Jha, dean of the Brown University School of Public Health, who noted that the percentage of positive tests is also on the decline. “That’s why I’m convinced the decline is real,” Dr. Jha said in an interview Friday night.

The decline, unfortunately, is also relative. Friday’s seven-day average of about 130,953 daily reported cases in the U.S. is still significantly higher than peaks in the spring and summer.

The Covid crisis is still with us. So why are the testing numbers going down?

Dr. Emily Martin, an associate professor of epidemiology at the University of Michigan, said that the recent dip in testing should come with “lots of caveats on what exactly it is we can take away” from the trend. It may be, she said, that testing spiked in January, possibly caused by people returning to jobs and schools after holiday breaks and being subjected to mandatory testing.

But Dr. Martin and other experts say that the numbers could also reflect a complacency about testing, as vaccine distribution is ramping up.

It is also possible that the dip reflects the burden on public health offices that are being asked to both administer vaccines and tests at the same time — and that vaccinations, in some cases, are taking precedence. The seven-day average of vaccinations has been on the rise, topping 1.3 million in recent days and approaching the Biden administration’s goal of 1.5 million doses per day.

“I do know that there are testing facilities that have been shifting their focus to vaccinations right now,” Dr. Guest said. “And I do wonder if the numbers we’re seeing go down are based on some shifting of priorities.”

And that is not particularly good news: Experts say that widespread testing must continue to be part of the fight against the pandemic, because scientists don’t know exactly how effective most of the vaccines are at slowing the spread of the virus. Vaccine trials, in the interest of speed, were designed primarily to study how effective the inoculations are against stopping the onset of severe Covid-19 disease and not whether they would prevent the transmission of the virus.

There was some progress on that front this week, with a study that showed that the vaccine developed by the University of Oxford and AstraZeneca has the potential to slow the transmission, according researchers at the university.


United States › United StatesOn Feb. 5 14-day change
New cases 129,316 –31%
New deaths 3,556 –5%

World › WorldOn Feb. 5 14-day change
New cases 523,201 –23%
New deaths 16,268 –5%

U.S. vaccinations ›

Where states are reporting vaccines given

Liz Halfhill, 30, works full time as a paralegal while in school and is her son’s primary caregiver. Some mornings, the two let out guttural screams — catharsis amid the stress of the past 11 months.
Credit…Brenda Ann Kenneally for The New York Times

In early September, as the school year inched closer, a group of mothers in New Jersey decided they would gather in a park, at a safe social distance, and scream their lungs out. For months, as the pandemic disrupted work and home life, these moms, like so many parents, had been stretched thin — acting as caregivers, teachers and earners at once. They were breaking.

As are mothers all over the United States.

By now, you have read the headlines, repeating like a depressing drum beat:

Working moms are not OK.” “Pandemic Triples Anxiety and Depression Symptoms in New Mothers.” “Working Moms Are Reaching the Breaking Point.”

You can also see the problem in numbers: Almost one million mothers have left the work force — with Black mothers, Hispanic mothers and single mothers among the hardest hit. Almost one in four children experienced food insecurity in 2020, which is intimately related to the loss of maternal income. And more than three quarters of parents with children ages 8 to 12 say the uncertainty around the school year is causing them stress.

Despite these alarm bells clanging, signaling a financial and emotional disaster among America’s mothers, who are doing most of the increased amount of child care and domestic work during this pandemic, the cultural and policy response enacted at this point has been nearly nonexistent.

The impact is not just about mothers’ fate as workers, though the economic fallout of these pandemic years might have lifelong consequences. The pandemic is also a mental health crisis for mothers that fervently needs to be addressed, or at the very least acknowledged.

Almost 70 percent of mothers say that worry and stress from the pandemic have damaged their health. The statistics are shocking, but they are sterile; they don’t begin to expose the frayed lives of American mothers and their children during this pandemic.

Jessica Bennett, a New York Times editor at large, spent months communicating with three women, who kept detailed diaries of their days, for a look at just how much American mothers are doing every waking second.

“With everything going on, I just don’t have time to take care of my mental health right now. I have to keep it together for everyone else,” said Dekeda Brown, 41, one of the three mothers featured in Ms. Bennett’s piece. “I feel like a ticking time bomb that is constantly being pushed to the breaking point, but then I am able to defuse myself. Goodness, this is taxing.”

“I don’t know how to feel sane again,” said Elise Kelner, 30, a mother of two children under 4, when she called in from Gilbert, Ariz. “I’m just stuck in this position for God knows how much longer.”

The Times collected the voices of women on a special phone line set up to give mothers across the country the opportunity to scream it out like the moms in New Jersey. Hundreds responded with shouts, cries, guttural yells and lots and lots of expletives.

Check out the series below, which shows all the messy, heartbreaking moments of everyday fear and chaos, and the rays of joy that can sometimes shine through.

A technician working in a Sinovac Biotech lab in Beijing, where the company is producing the vaccine CoronaVac.
Credit…Kevin Frayer/Getty Images

Beijing has approved a second Chinese Covid-19 vaccine — a drug made by Sinovac Biotech that will be distributed to developing countries — in a move that furthers the country’s efforts to be a global player in ending the pandemic.

Sinovac said in a statement on Saturday that it had received conditional approval from China’s National Medical Products Administration a day earlier. In December, China approved a vaccine made by Sinopharm Group, a state-owned company.

Sinovac and Sinopharm have released little data from late-stage trials that would allow scientists to draw independent conclusions on their vaccines’ efficacy. Sinovac’s vaccine, CoronaVac, has had four different efficacy rates announced in recent months by the countries that conducted Phase 3 trials. In the most recent, Brazilian officials said that CoronaVac had an efficacy rate of just over 50 percent, though those who received it and still became infected showed only “very mild symptoms.”

Sinovac said the approval was based on two months of clinical trial data. It said it had not obtained the final analysis data, adding that “the effectiveness and safety results have yet to be further confirmed.”

Sinovac has struck deals with at least 11 countries and regions, including Brazil, Chile, Indonesia and Turkey, in keeping with President Xi Jinping’s promise last year that a Chinese Covid-19 vaccine would be a global public good.

Sinovac said it had completed a second production line that would increase its manufacturing capacity to more than one billion doses after it is put into use this month.

Even before the completion of late-stage trials, Chinese officials approved the vaccines from Sinopharm and Sinovac for emergency use and rolled them out to millions of people, prompting criticism from scientists who argued that the move could pose a risk to public health.

People lining up to buy food in Havana this week as Cuba experiences a surge of coronavirus infections. A curfew will be imposed to slow the spread of the virus.
Credit…Ernesto Mastrascusa/EPA, via Shutterstock

A curfew will be imposed in Havana on Friday night as Cuba tries to parry its biggest coronavirus spike since the beginning of the pandemic.

The Havana Tribune, a provincial newspaper of the Communist Party of Cuba, informed the capital’s population that a “total restriction of movement of people and vehicles” will be imposed from 9 p.m. to 5 a.m. and that the curfew “will remain in place until the epidemiological situation is favorable.”

The curfew is part of a package of measures applied in recent weeks to help curb the spread of the virus: Last month, schools were closed and public transport was cut back. Starting tomorrow, travelers entering the country will be forced to quarantine for five days — Cubans in state-run isolation centers at no cost, foreigners in hotels at their own expense. The number of flights from Covid-19 hot spots, including the United States, Colombia and the Dominican Republic, will be reduced as well.

Cuba is the first country in Latin America to develop, produce and test its own Covid-19 vaccines. Four vaccines are currently being tested in clinical trials. Sovereign II, the vaccine that has advanced the furthest, is expected to start Phase 3 testing in March and mass production in April. Cuba aims to vaccinate its entire population and produce 100 million doses this year. Surplus doses will be exported.

Health authorities say that tourists will be able to receive jabs during their stay, creating the prospect of health tourism once workers at package holiday destinations have been vaccinated. Tourism, one of the island’s main industries, has all but disappeared since the pandemic, leading to massive lines for groceries and even bread shortages. The prospect of a swift vaccination campaign and the return of tourist dollars by the high season in the fall may make the wait for basic goods and the curfew a little easier for the capital’s inhabitants.

Cuba reported only 12,225 confirmed cases and 146 deaths last year, but case numbers shot up during January. So far this month, the island has averaged around 900 confirmed cases per day, with over a third in Havana.

Credit…Yamil Lage/Agence France-Presse — Getty Images
A film director, John Soares, receiving communion at the Cathedral of Our Lady of the Angels in downtown Los Angeles in June of last year. 
Credit…Damian Dovarganes/Associated Press

A splintered Supreme Court on late Friday night partly lifted restrictions on religious services in California that had been prompted by the pandemic.

The court ruled in cases brought by South Bay United Pentecostal Church in Chula Vista and Harvest Rock Church in Pasadena. The churches said restrictions imposed by Gov. Gavin Newsom, a Democrat, violated the Constitution’s protection of the free exercise of religion.

The restrictions set varying limits on attendance at religious services by county, depending on infection rates. With the pandemic raging, in-person worship services were entirely barred in Tier 1, which covers almost all of the state.

In a brief, unsigned opinion, the court blocked that total ban but left in place a 25 percent capacity restriction and a prohibition on singing and chanting. Justices Clarence Thomas and Neil M. Gorsuch said they would have blocked all of the restrictions. Justices Stephen G. Breyer, Sonia Sotomayor and Elena Kagan dissented, saying they would have left all of the restrictions in place.

Chief Justice John G. Roberts Jr., in a concurring opinion, explained why a middle ground was appropriate. He said that the court should generally defer to public health experts but that there were limits to that deference.

“The state has concluded, for example, that singing indoors poses a heightened risk of transmitting Covid-19,” he wrote. “I see no basis in this record for overriding that aspect of the state public health framework.”

“At the same time,” the chief justice continued, “the state’s present determination — that the maximum number of adherents who can safely worship in the most cavernous cathedral is zero — appears to reflect not expertise or discretion, but instead insufficient appreciation or consideration of the interests at stake.”

Justice Amy Coney Barrett, in her first opinion, wrote that she would not have blocked the restrictions on singing and chanting based on the available evidence. Justice Brett M. Kavanaugh joined her opinion.

Justice Gorsuch, joined by Justices Thomas and Samuel A. Alito Jr., said the state had favored its entertainment industry over worship services.

“If Hollywood may host a studio audience or film a singing competition while not a single soul may enter California’s churches, synagogues and mosques,” Justice Gorsuch wrote, “something has gone seriously awry.”

In dissent, Justice Kagan, joined by Justices Breyer and Sotomayor, said the majority had intruded into matters best left to public health officials.

“Justices of this court are not scientists,” Justice Kagan wrote. “Nor do we know much about public health policy. Yet today the court displaces the judgments of experts about how to respond to a raging pandemic.”

The ruling followed a similar one in November in a case from New York.

Hudson Yards has suffered during the pandemic, raising questions about its future.
Credit…Todd Heisler/The New York Times

When Hudson Yards opened in 2019 as the largest private development in American history, it aspired to transform Manhattan’s Far West Side with a sleek spread of ultraluxury condominiums, office towers for powerhouse companies like Facebook, and a mall with coveted international brands and restaurants by celebrity chefs like José Andrés.

All of it surrounded a copper-colored sculpture that was supposed to be to New York what the Eiffel Tower is to Paris.

But the pandemic has ravaged New York City’s real estate market and its premier, $25 billion development, raising significant questions about the future of Hudson Yards and signaling the broader challenges facing the city as it tries to recover.

Hundreds of condominiums remain unsold, and the mall is barren of customers. Its anchor tenant, Neiman Marcus, filed for bankruptcy and closed permanently, and at least four other stores, as well as several restaurants, have also gone out of business.

The development’s centerpiece, the 150-foot-tall scalable structure known as the Vessel, closed to visitors in January after a third suicide in less than a year. The office buildings, whose workers sustained many of the shops and restaurants, have been largely empty since last spring.

Even more perilous, the promised second phase of Hudson Yards — eight additional buildings, including a school, more luxury condos and office space — appears on indefinite hold as the developer, the Related Companies, seeks federal financing for a nearly 10-acre platform on which it will be built.

Related, which had said the entire project would be finished in 2024, no longer offers an estimated completion date.

Experts are warning that posting a selfie with your Covid-19 vaccine card might make you vulnerable to identity theft or scams.
Credit…Dan Busey/The TimesDaily, via Associated Press

So you finally got a Covid-19 vaccine. Relieved, you take a photograph of your vaccination card, showing your name and birth date and which vaccine you had, and publish it on social media.

But some experts are warning that the information on the celebratory photo might make you vulnerable to identity theft or scams.

“Unfortunately, your card has your full name and birthday on it, as well as information about where you got your vaccine,” the Better Business Bureau said last week. “If your social media privacy settings aren’t set high, you may be giving valuable information away for anyone to use.”

On Friday, the Federal Trade Commission followed suit: “You’re posting a photo of your vaccination card on social media. Please — don’t do that!” it warned bluntly. “You could be inviting identity theft.”

Scammers can sometimes figure out most digits of your Social Security number by knowing your date and place of birth, and can open new accounts in your name, claim your tax refund for themselves, and engage in other identity theft, said Maneesha Mithal, associate director of the Federal Trade Commission’s Division of Privacy and Identity Protection.

“Identity theft is like a puzzle, made up of pieces of personal information,” Ms. Mithal said. “You don’t want to hand over to identity thieves the pieces they need to complete the picture. One of those pieces is your date of birth.”

Tiffany Tate, executive director of the Maryland Partnership for Prevention, is accusing Deloitte and the Centers for Disease Control and Prevention of stealing her intellectual property.
Credit…Saul Martinez for The New York Times

Last spring, when coronavirus vaccines were just a glimmer of hope, the Trump administration awarded the first of two no-bid contracts worth up to $44 million to a national consulting firm to help patients register to be immunized and states collect detailed data on vaccine recipients.

The result was VAMS, a vaccine administration management system built by the firm, Deloitte, which has been spurned by most states and become an object of scorn. And now, an immunization expert who had offered the government her own mass vaccination tracker at a lower price than Deloitte’s is accusing the company and the Centers for Disease Control and Prevention of stealing her intellectual property.

Tiffany Tate, the executive director of the Maryland Partnership for Prevention, made the allegation in a cease-and-desist letter obtained by The New York Times, and later confirmed its authenticity in an interview with her lawyer on Friday. Ms. Tate, who has spent two decades running immunization clinics in underserved communities, said she previewed her platform last May for Deloitte officials who were identified by the C.D.C. as consultants.

The C.D.C. expressed interest in buying it, she said. But the centers instead asked Deloitte, without a competitive bidding process, to build its own system, dismissing warnings from state and local health officials and immunization managers that it was unwise to roll out an untested platform in the middle of a crisis.

The letter, dated Aug. 30, says the C.D.C.’s specifications “mirror” the system Ms. Tate created — including a “new feature” that “eventually found its way into VAMS.” Ms. Tate, who is African-American and whose work has focused on minority communities, said the rejection was especially painful in the thick of a pandemic that disproportionately affects people of color.

“I was in shock, and I really was heartbroken because I’ve worked with these people my entire career and I respected them and I trusted them,” Ms. Tate said in the interview. “It was very, very upsetting.”

Ultimately, the marketplace spoke. VAMS, which Mississippi’s state health officer, Dr. Thomas E. Dobbs, described this week as “suboptimal,” is being used in about 10 states. Ms. Tate offered to license her own system for $15 million — about a third what the C.D.C. has committed to pay Deloitte — so the centers could give it free to states. When the C.D.C. rejected her, she said, she sold it to states herself.

Now, 27 states and jurisdictions (not 28 states as an earlier version of this briefing item reported) are using it.

The C.D.C. did not respond to a request for comment. Deloitte dismissed Ms. Tate’s claims as “baseless” in a statement issued by its spokesman.

Tobacco sales in the U.S. have typically declined in recent decades. In 2020, they remained flat.
Credit…Jeff Chiu/Associated Press

Lots of people seem to be smoking again or more during the pandemic, if anecdotal evidence and preliminary sales figures for tobacco products are any measure.

“Good quality surveys operate at a lag,” said Vaughan W. Rees, the director of the Center for Global Tobacco Control at Harvard University, referring to reliable smoking studies from institutions like the Centers for Disease Control and Prevention. “But we are seeing interesting blips. The decline in tobacco sales has slowed in the past 10 months.”

While tobacco sales in the United States have generally fallen in recent decades (14 percent of Americans smoked in 2019, compared to nearly 21 percent in 2005, according to an annual report from the C.D.C. that tracks smoking rates), the decline flattened last year.

“The total volume of cigarettes sold in the U.S. typically declines by 3 or 4 percent,” said Adam Spielman, a managing director at Citi who follows the tobacco industry. “But in 2020, volume is flat and that’s a significant change, driven mostly by the fact that people have less things to spend money on right now.”

Smokers also cited stress as a reason for lighting up.

“I’ve had a few people in my practice who have relapsed and they blame Covid,” said Benjamin A. Toll, the director of the Health Tobacco Treatment Program at Medical University of South Carolina. “Part of me feels like this is the excuse of the hour.”

Matt Lundquist, a psychotherapist and founder of Tribeca Therapy in Manhattan said, “When things are scary, people revert to that which is comforting and familiar, like going out to buy a pack of cigarettes.”

Hannah Wise received the first dose of the Pfizer-BioNTech Covid-19 vaccine on Wednesday.
Credit…Hannah Wise

One morning this week, as I was driving 90 minutes down a highway, past frost-covered fields and bright white church steeples, I finally cried. I was on my way to get the vaccine, and after nearly a year of bottling up emotions, they were suddenly pouring out.

I qualified for the vaccine in Missouri’s Phase 1B-Tier 2 because I have Crohn’s disease, an autoimmune illness that affects the intestinal tract, as well as psoriasis and psoriatic arthritis — conditions managed through a rigid medication schedule that suppresses the immune system, leaving people like me particularly vulnerable to severe illness from the coronavirus.

The virus has felt inescapable, as it has for so many people. At work, as an editor at The New York Times, I read story after story about the loss of life and try to find words to help readers understand and process the pandemic’s toll. At home, the virus has laid bare my own health concerns. I moved to Kansas City, Mo., from New York in June, after 100 days alone in my apartment, to be closer to family in case I were to be infected.

Every step outside my apartment has felt like a calculated risk.

Driving east on I-50 toward the Missouri State Fairgrounds in Sedalia, I felt all the emotions of the year bursting forth. Could this be what hope feels like?

Getting a vaccine is far from guaranteed, even for the two million Missourians who qualify. As of Feb. 4, only 6.3 percent of the state’s six million residents have received one vaccine dose.

I set up alerts to see every tweet from Gov. Mike Parson, the Kansas City and Jackson County health departments and nearly every hospital system in the area. A tweet is how I learned about openings at a state-run mass vaccination event.

On Monday, I signed up for my fourth vaccine list. Tuesday afternoon, I got the call: My appointment would be the next day.

Inside the agricultural building turned vaccine clinic, I was one of the youngest patients. Concerned that I’d be turned away at the door because my disability is invisible, I rattled off my conditions as I checked in. But my paperwork was there waiting for me.

Samantha Unkel, 24, who comes from a family of nurses, said she was excited to give me the vaccine. I felt tears welling up again behind my mask. She congratulated me as I took my vaccine selfie.

I’ve felt a physical lightness since the shot. It is a glimmer of joy during a dark and cold winter. Friends who will likely not be vaccinated for many months said that my vaccination cheered them too: evidence of tangible progress.

At the end of February, I hope to drive back for my second dose. My life after the vaccine will look much like my life before. I’ll still be wearing my mask and social distancing, but I’ll do so with less fear.

Pharmacists prepared to administer the AstraZeneca-Oxford Covid-19 vaccine on Thursday in Birmingham, England.
Credit…Oli Scarff/Agence France-Presse — Getty Images

A series of new findings about a vaccine developed by AstraZeneca and the University of Oxford this week show some promising results on several fronts: slowing the spread of the virus, protecting against a more contagious variant and possibly being effective in just one dose.

Researchers reported that a single dose of the AstraZeneca vaccine provided strong protection against Covid-19 even when its second shots were delayed by at least three months. The results help sustain the strategy used by Britain and other countries to prioritize providing as many first doses of vaccines as possible without worrying that people will get their second doses later than initially planned.

The paper also showed that the vaccine has the potential to slow the transmission of the virus itself, though scientists have emphasized that the data are preliminary and that the degree of protection is unknown. Studies so far have been focused on determining whether vaccines could prevent the onset of severe Covid-19.

Another report released later in the week on the vaccine showed it was about as effective against the more contagious virus variant found in Britain as it was against other lineages of the virus. The paper, which has not yet been peer-reviewed, said that the vaccine had 74.6 percent efficacy against the variant, which U.S. officials have warned could become dominant by the spring.

However, as the variant has circulated in Britain, it has gained a new and worrisome mutation — the same mutation that scientists believe explains the vaccine resistance of the variant found in South Africa.

In other news from the past week:

  • Almost half of U.S. states have begun allowing teachers to be vaccinated. How quickly states give shots to teachers from a growing-but-still-limited vaccine supply has become a central point in the debate about how best to reopen school systems. By this week, 24 states and Washington, D.C., were providing shots to teachers of kindergarten through high school students.

  • Moderna is asking U.S. regulators to allow it to increase the amount of vaccine put into each vial by as much as 50 percent. The upstart drugmaker says it can raise the doses per vial to as much as 15 doses from 10. The F.D.A. could decide within a few weeks if the company can up the dosages.

  • The federal government is expected to send one million vaccine doses to about 6,500 retail pharmacies across the United States on Thursday, the beginning of a federal program that will deliver vaccines directly to as many as 40,000 drugstores and grocery stores, Jeffrey D. Zients, the White House’s Covid-19 response coordinator, announced on Tuesday. The federal program will not cut into the doses allocated to states — and over time, it will greatly expand the number of sites where eligible people can get vaccines.

  • New York became the latest state to decide to expand vaccine eligibility beyond health care workers and residents of long-term care facilities. Gov. Andrew M. Cuomo announced on Friday that, as of Feb. 15, the state would allow vaccinations for people with some chronic health conditions that put them at greater risk of severe Covid. The conditions include cancer, heart conditions, lung diseases, liver disease, diabetes and obesity, among others. (The Centers for Disease Control and Prevention’s advisory committee has told pregnant women to consult with their doctors before receiving the vaccine.)

A lab worker, London Pasquarello, opening test samples at Duke University on Wednesday. 
Credit…Pete Kiehart for The New York Times

Scientists have been sounding the alarm about new variants of the coronavirus that carry a handful of tiny mutations, some of which seem to make vaccines less effective.

But the novel coronavirus also has a propensity to mix large chunks of its genome when it makes copies of itself. Unlike the small mutations, which are like typos in the sequence, a phenomenon called recombination resembles a major copy-and-paste error in which the second half of a sentence is completely overwritten with a slightly different version.

A flurry of new studies suggests that recombination may allow the virus to shapeshift in dangerous ways.

The coronavirus mutations that most people have heard about, such as those in the B.1.351 variant first detected in South Africa, are changes in a single “letter” of the virus’s long genetic sequence, or RNA. Because the virus has a robust system for proofreading its RNA code, these small mutations are relatively rare.

Recombination, in contrast, is rife in coronaviruses.

Researchers at Vanderbilt University Medical Center recently studied how things go awry during replication in three coronaviruses, including SARS-CoV-2, which causes Covid. The team found that all three viruses showed “extensive” recombination in the laboratory.

Scientists worry that recombination might allow for different variants of the coronavirus to combine into more dangerous versions inside a person’s body. The B.1.1.7 variant first detected in Britain, for example, had more than a dozen mutations that seemed to appear suddenly.

Nels Elde, an evolutionary geneticist at the University of Utah, said that recombination may have merged mutations from different variants that arose spontaneously within the same person over time or that co-infected someone simultaneously. For now, he said, that idea is speculative: “It’s really hard to see these invisible scars from a recombination event.” And although getting infected with two variants at once is possible, it’s thought to be rare.