Here’s what you need to know:
As the United States continues breaking record after record — over 194,000 new cases in a single day on Friday, more than 82,000 people hospitalized — some states and cities are hoping nightly curfews will help stop the coronavirus from leaping person to person at bars, parties and other nocturnal events.
California is the latest to issue an overnight curfew, a measure more often imposed to calm public unrest than for the sake of public health.
Gov. Gavin Newsom of California, a Democrat, issued the order for most of the state’s counties on Thursday, requiring that, beginning Saturday, people not leave their homes between 10 p.m. and 5 a.m. except for essential reasons, and that restaurants close for dining then as well. Gov. Mike DeWine of Ohio, a Republican, issued a similar curfew that went into effect on Thursday.
At the local level, some areas have also imposed curfews, such as Pueblo, Colo., and Miami-Dade County, Fla., while several cities, including New York and Chicago, have shut down bars and restaurants at 10 p.m.
The measures also show how widely the response to the virus can vary by state. None of the states where the virus is spreading at the fastest rates — South Dakota, North Dakota, Wyoming, Iowa and Nebraska — have issued curfews, even as governors of some of those states have begun to require face masks indoors for the first time.
The changes come as the virus has, in the past week, killed more than 1,300 people and infected more than 166,000 new people each day, on average as of Thursday.
Public health officials have repeatedly warned that the virus can spread more easily at late-night gatherings as people shout, sing, get closer to each other or, perhaps, flout the rules as they drink. In June, health officials in Ada County, Idaho, which includes Boise, determined that half of the area’s newly sick were people who had likely gotten the virus from bars and nightclubs.
“The rules for when bars are open are supposed to be that you can come down with your group and you don’t interact with others,” said Mayor Nicholas Gradisar of Pueblo, Colo., a city of about 112,000 people where a curfew has been extended to Nov. 27. But people sometimes don’t follow those rules after they have been drinking, he added. “That’s how this virus spreads.”
Public health experts also caution that it can take several weeks for measures like mask mandates, restaurant closings and restrictions on gathering to influence people’s behavior and start to flatten the epidemic curve. The effect may be delayed because the incubation period for the disease is up to 14 days, so some proportion of the public is already infected.
A spokesman for Mr. DeWine said he believed Ohio’s three-week curfew “can make a dent” in the state’s rising cases while letting bars and restaurants continue to make money by serving people earlier in the evening.
Dr. Mark Ghaly, the secretary of California Health and Human Services, said that the state’s curfew was targeted to stop the most harmful behaviors.
“We’ve seen in the past that Covid goes from zero to 60 miles per hour very quickly,” he said at a news conference on Thursday. “We know that those who are out, who might be engaging in higher-risk behaviors, that those infections can quickly spread to other settings.”
The drug maker Pfizer said on Friday that it had submitted an application to the Food and Drug Administration to authorize its coronavirus vaccine for emergency use, setting in motion an accelerated regulatory process that could allow the first Americans to get a vaccine by the middle of December.
Pfizer and its German partner, BioNTech, announced on Wednesday that the vaccine was safe and 95 percent effective, and that it also worked well in older people and in preventing severe Covid-19. Another front-runner, Moderna, said on Monday that its vaccine, which uses similar technology, was 94.5 percent effective and that the company also expected to apply soon for emergency authorization.
An emergency authorization would allow limited groups of Americans to get the vaccines before the F.D.A. has completed the typical monthslong approval process. Agency officials have made clear through new guidelines that their bar for emergency authorization will be high.
The F.D.A. regulators plan to take about three weeks to review Pfizer’s vaccine, which spans thousands of pages, before an outside panel of experts meets to review the application. That meeting has been scheduled for Dec. 10.