As daily covid-19 deaths climb to levels not seen since early in the pandemic, nine states have hit one more grim marker: more than 1 in every 1,000 people dead of coronavirus-related causes.

The list reflects the far-reaching toll of the crisis, spanning early hot spots, Southern states hit hard in the summer and rural parts of the country with increasingly strained hospitals. And it is growing.

On Friday, South Dakota became the latest state to see at least one covid-19 death for every 1,000 residents, joining New York, New Jersey, Massachusetts, Connecticut, Louisiana, Rhode Island, Mississippi and North Dakota. The country also surpassed 13 million known coronavirus cases during a holiday season upended by the pandemic. Even with travel significantly down from last year, millions went through airport checkpoints in the days leading up to Thanksgiving, and governors on Friday urged people not to let down their guard amid Black Friday shopping.

Thanksgiving’s contributions to the spread of the virus may not be apparent until next week, when reporting becomes more regular again and when people who may have gotten infected at family gatherings receive their test results. Officials’ calls to minimize travel and large get-togethers came as powerful tools to fight the virus move closer to reality — the Federal Aviation Administration said Friday that it was supporting “the first mass air shipment” of a coronavirus vaccine — but also as the country struggles to respond to a cold-weather viral surge.

That wave and the consequent strain on hospitals have prompted a new round of painful business closures and stay-at-home orders. Los Angeles County, home to 10 million people, on Friday announced new rules — set to take effect Monday and last for three weeks — limiting business capacity and banning all gatherings of people outside one’s household, with exceptions for church services and protests. The county has already restricted restaurants to takeout, drive-through and delivery, and California has imposed curfews forbidding “nonessential activities” overnight for most of its population.

With lawmakers at the federal level deadlocked on a new economic aid package, President Trump tweeted Friday night: “The restaurant business is being absolutely decimated. Congress should step up and help. Time is of the essence!”

Some long-reluctant Republican governors have recently adopted statewide mask orders and stricter social distancing measures. But leaders’ actions vary widely.

In South Dakota, for instance, Gov. Kristi L. Noem (R) remains resistant to a statewide mask mandate. She has also given her blessing to mass gatherings, encouraging people to come out over the summer for a nearly 500,000-person motorcycle rally that many experts feared would be a superspreader of the virus.

Within weeks of the 10-day rally, the Dakotas, along with Wyoming, Minnesota and Montana, had the highest new infections per capita in the country, though experts say it is impossible to know how many of those cases stemmed from the event, given failures to track and contact-trace attendees.

While Noem attributed spiking cases in the wake of the gathering to increased testing — echoing Trump’s statements about the United States as a whole — that cannot account for the recent surge, and current covid-19 hospitalizations in South Dakota also rose dramatically. Hospitalizations in the state exploded in September after remaining close to or below 100, peaking earlier this month at more than 600.

The crush of patients now straining the health-care system in South Dakota is emblematic of the pandemic’s worsening onslaught throughout the country as winter approaches, sending more people indoors, where the virus is more likely to spread. The country logged more than 2,200 new deaths Wednesday, the highest daily increase since May 6.

The United States’ record-setting daily case numbers are an undercount of the virus’s actual reach: A new study from researchers at the Centers for Disease Control and Prevention estimates that only about 1 in 8 coronavirus infections nationwide were reported through the end of September. While roughly 7.2 million infections were reported in that time frame, the CDC estimates that the true number may have been closer to 52.9 million.

Health officials asked people who gathered with others for Thanksgiving to get tested for the virus. Anthony S. Fauci, director of the National Institute of Allergy and Infectious Diseases, predicted that Christmas and New Year’s celebrations will need to be as subdued as Thanksgiving.

“If the surge takes a turn of continuing to go up and you have the sustained greater than 100,000 infections a day and 1,300 deaths per day and the count keeps going up and up … I don’t see it being any different during the Christmas and New Year’s holidays than during Thanksgiving,” he told USA Today in an article published Friday.

Superspreader events are the leading cause of coronavirus transmission in the U.S. Here’s what they entail, and why they are so dangerous. (The Washington Post)

Hope may be in sight, with vaccines pending regulatory approval — though getting any greenlighted shots into millions of people’s arms is no easy task. The Friday air shipment announced by the FAA, which says it created a coronavirus air transport team in October, marked one step forward in that complex process.

The Wall Street Journal reported that United Airlines Holdings Inc. began flying doses of Pfizer’s vaccine to be ready for distribution if it wins government approval. Pfizer and its German partner BioNTech last week became the first companies to seek emergency authorization for a coronavirus vaccine. Between that and a shot created by Moderna, U.S. officials say they expect about 20 million people to be inoculated nationwide in December.

Pfizer did not immediately respond to an inquiry Friday night. United Airlines did not address the reported transport Friday but said in a statement that it has been working to “support a vaccine distribution effort on a global scale.”

Questions are swirling, meanwhile, about the coronavirus vaccine developed by pharmaceutical company AstraZeneca with the University of Oxford, one of three early contenders for approval from the Food and Drug Administration. Critics suggested the company was less than transparent and wondered whether its results would stand up to scrutiny.

AstraZeneca chief executive Pascal Soriot told Bloomberg News that his company was likely to run a new trial to test the most positive portion of its data, which reported 90 percent effectiveness when a small group of people mistakenly received only half the initial dose of a two-dose regimen.

Katherine O’Brien, director of immunization, vaccines and biologicals for the World Health Organization, said that while AstraZeneca’s data shows promise, there are many ways the findings could still be undercut. She said experts need access to the underlying data to draw conclusions about the trial’s results.

“It’s too early for us to say anything about what we make of the data and what is needed next,” O’Brien said Friday at a news conference. “What we really need to see is more than a press release.”

AstraZeneca narrowly avoided another significant problem when suspected North Korean hackers tried to gain access to the company’s internal systems in recent weeks, Reuters reported. The attempts are not believed to have been successful.

Until a vaccine is widely available, government officials across the United States are scrambling to impose new restrictions to curtail the spread while avoiding wholesale shutdowns like those in the spring. In the past week, Nevada, New York and the D.C. area, among other regions, have seen tightened rules on public gatherings.

Some jurisdictions implemented especially stringent rules for Thanksgiving weekend, including San Antonio and Bexar County, Tex., where residents are not allowed to gather outside their homes between 10 p.m. and 5 a.m. unless they are traveling to or from a business. In Pennsylvania, Gov. Tom Wolf (D) shut down liquor sales in bars and restaurants on Wednesday night, putting the kibosh on a popular annual nightlife event.

Florida Gov. Ron DeSantis (R), in contrast, on Tuesday extended an executive order that bans city and county governments from enforcing mask ordinances or limits on restaurant capacity.

But most governors have been striking a cautious tone, urging residents to wear masks and maintain social distance from others, despite pandemic fatigue.

“Please support Ohio businesses on #BlackFriday!” tweeted Ohio Gov. Mike DeWine (R). “Online, delivery, or contactless pickup are your safest shopping options, but if you do shop in person, remember that social distancing/mask-wearing are essential! These measures will help prevent #COVID19 spread while you shop.”

Across the Atlantic, the United Kingdom reported hopeful news about the spread of the virus there. British officials estimated that the virus’s reproduction rate, known as R0 and pronounced “r-naught,” was below 1 and that the number of new infections was falling by up to 2 percent per day. R0 measures how many other people a person with the virus infects on average, and it sheds light on whether an outbreak is worsening in a particular area.

Other countries have announced the loosening of restrictions, including Ireland, which will reopen stores, restaurants and gyms next week. Italy is allowing more movement in five regions after hospitalizations gradually declined over the past few days. Officials in France and Britain have said they will ease the rules for the holiday season.

Maria Van Kerkhove, the WHO’s technical lead on the coronavirus, warned that countries should not become lax, even if their case numbers are falling.

“What we don’t want to see is situations where you’re moving from a so-called lockdown state to bringing the virus under control to moving to a so-called lockdown state,” she said at the news conference.

The news was less optimistic elsewhere, including one of the last countries to record a coronavirus infection: the Polynesian island nation of Samoa, which confirmed its first case in a man who had recently returned from Australia.

Iran reported a record number of new infections and partly closed government offices, while Germany became the 12th country to surpass 1 million cases. German Chancellor Angela Merkel is advocating for a European Union-wide ban on ski tourism around Christmas, but other nations have resisted.

Jacqueline Dupree, Lena H. Sun, Brittany Shammas and Miriam Berger contributed to this report.