Covid-19 Live Updates: Latest News and Analysis

Under 10 percent of Americans have coronavirus antibodies, a study finds.

Less than 10 percent of people in the United States have antibodies to the coronavirus, suggesting that the nation is even further from herd immunity than was previously estimated, according to a study published on Friday in The Lancet.

The study looked at blood samples from 28,500 patients on dialysis in 46 states, the first such nationwide analysis.

The results roughly matched those of an analysis to be released next week by the Centers for Disease Control and Prevention, which found that about 10 percent of blood samples from sites across the country contained antibodies to the virus.

Dr. Robert R. Redfield, the director of the C.D.C., was referring to that analysis when he told a congressional committee this week that 90 percent of people in the country were still vulnerable to the virus, a C.D.C. spokeswoman said.

An accurate estimate of the country’s immunity is important because President Trump, in collaboration with his new medical adviser, Dr. Scott Atlas, has tentatively promoted the idea of reaching herd immunity by canceling lockdowns, mask-wearing campaigns and social-distancing mandates. The plan would be to let the virus wash through the population while trying to protect the people deemed most vulnerable.

Most public health experts say that such a policy would lead to hundreds of thousands of additional deaths, as it is impossible to protect all Americans who are elderly or have underlying conditions like diabetes and heart disease that render a person more likely to become seriously ill or to die.

The study of dialysis patients, done by scientists from Stanford University, found wide variances in antibody levels around the country. In the New York metropolitan area, including New Jersey, antibody levels were higher than 25 percent of samples tested. In the western United States, they were below 5 percent.

Over all, the researchers estimated the prevalence to be about 9.3 percent.

The implication, Dr. Redfield said in a statement, is that most people in the country are still susceptible to the virus and therefore should continue to take steps such as wearing masks, staying six feet away from other people, washing hands frequently, staying home when sick and “being smart about crowds.”

More than 130,000 coronavirus cases have been identified at American colleges over the course of the pandemic, according to a New York Times survey. That figure has grown by tens of thousands since early September as fall classes have continued despite major uncontrolled outbreaks.

Infections have emerged at large public universities, elite private schools and community colleges. Of more than 1,600 colleges surveyed by The Times, more than 1,300 reported at least one case and at least 35 colleges had more than 1,000 infections.

Read more: See the full list of colleges with coronavirus cases.

Although some schools did not reopen this fall and others shifted online after a brief return to campus, many have forged ahead with a highly unusual semester. But as clusters have continued to emerge in residence halls, in fraternity houses and on sports teams, the outbreaks have upended campus life.

Brigham Young University ended visiting hours at its dorms and stopped intramural sports as infection numbers grew. The University of Colorado’s flagship campus shifted to online classes in hopes of controlling an outbreak. And in Wisconsin, where college towns are contributing to a statewide spike in cases, Lt. Gov. Mandela Barnes gave a radio address pleading with students to wear masks.

“College isn’t just about your coursework 24/7. Believe me, I get it,” Mr. Barnes said. “But in order for you to participate in all the things that make college so memorable, you all need to wear masks anytime you leave the dorm room or your apartment.”

  • After the pandemic prevented many high school students from taking college admissions tests for months, the SAT added a September date for the first time in decades, and more than 334,000 students registered to sit the exam on Saturday. Now, at least half won’t be able to take it. Nearly four in 10 testing sites told the College Board that they would be closed because of concerns about the spread of the coronavirus.

Navajo Nation reinstates a full weekend lockdown as cases surge again.

The Navajo Nation, the largest Native American reservation, has reinstated a full weekend lockdown to try to contain new spikes in infections.

The reservation recently experienced a stretch of weeks with few or no new virus cases on some days, but then new clusters were detected, and new daily cases reached 42 on Thursday, followed by 26 on Friday.

Jonathan Nez, the Navajo Nation’s president, said that contact tracers had found the new clusters to be connected to Navajo citizens who had contracted the virus after traveling off the reservation. All three of the states the nation is spread over — Arizona, New Mexico and Utah — are enduring high or rising rates of infection, and only New Mexico has a statewide mask requirement.

“Please do not hold family gatherings, and please do not travel to hot spots off the Navajo Nation,” Mr. Nez said in a statement after the new clusters were disclosed.

“I feel sorry for Americans,” said U Myint Oo, a member of Parliament in Myanmar, a poor country struggling with open ethnic warfare and a coronavirus outbreak that could overload its hospitals. “But we can’t help the U.S. because we are a very small country.”

The same sentiment prevails in Canada.

“Personally, it’s like watching the decline of the Roman Empire,” said Mike Bradley, the mayor of Sarnia, a Canadian city on the border with Michigan.

Bali, the engine of Indonesia’s tourism industry, has long attracted domestic and foreign tourists with its wide beaches, scenic rice fields, religious ceremonies and an active volcano.

Mr. Koster, who previously promoted inhaling the steam of a traditional alcoholic beverage as a treatment for Covid-19, said this week that he was “horrified” by the spread of the illness in his household. He urged people to take the virus seriously, saying: “If anyone says that the coronavirus is a conspiracy, it is not true.”

The governor said last month that more than 75,000 people on the island were out of work. Many hotel workers have returned to their home villages, where they can help their families grow food. Others, who don’t have access to farmland, are struggling to feed themselves.

Since reopening to domestic travelers at the end of July, Bali’s reported cases have more than doubled to 8,389 and the number of deaths has risen more than fivefold to 245. The central government has said it will not open the island to foreign tourists until at least the end of the year.

The French Open adjusts ambitious plans amid the country’s surging caseload.

The French Open tennis tournament begins on Sunday in Paris, where residents have spent the past couple of months enjoying long afternoons and evenings at cafes, being able to visit some of the world’s best-known museums, and attending school in person.

Given that, French Open organizers aimed to make their event more lenient than the recently completed U.S. Open in New York, where players remained largely isolated and closely watched, while ticket-buying spectators were prohibited.

But with cases of coronavirus spiking in France, government officials have reintroduced strict limits on the size of gatherings. Now, just 1,000 fans are expected each day at Roland Garros, the jewel-box facility in western Paris that hosts the Grand Slam event.

Yet differences between how players are living in Paris and their stay in the United States are notable.

Most U.S. Open players spent as many as four weeks isolated in a Long Island hotel. The athletes were allowed to rent a private home, but not to leave except to play and train.

In Paris, all players — even players who own homes in the city — must stay in two hotels, which they are sharing with members of the public, though the players and their entourages are on separate floors.

Already, organizers have eliminated a coach and at least seven players for either testing positive or being exposed to a coach who did.

But there are not strict rules on where players can venture or eat in Paris. They are merely encouraged to take personal responsibility and respect social distancing guidelines.

As if working mothers did not have enough to worry about, experts are sounding the alarm that progress toward gender equality may be a casualty of the pandemic.

Reporting was contributed by Hannah Beech, Emma Bubola, Karen Crouse, Matthew Futterman, Mike Ives, Donald G. McNeil Jr., Richard C. Paddock, Simon Romero, Adam Satariano, Mitch Smith, Amanda Taub and Sui-Lee Wee.