Airline crew members wear full hazmat suits as they arrive at Los Angeles International Airport this week. The Transportation Security Administration reported nearly 1.1 million people passed through airport security checkpoints Wednesday, the agency’s highest screening volume since March 16. (Etienne Laurent/EPA-EFE/REX/Shutterstock)

Americans endured a gloomy Thanksgiving on Thursday, as coronavirus cases continued to surge while questions swirled about how to interpret results from a top vaccine candidate.

Despite pleas from top government leaders and scientists for Americans to scale back Thanksgiving gatherings this year, it appeared that a large number still tried to gather with loved ones.

The Transportation Security Administration reported that nearly 1.1 million people passed through airport security checkpoints Wednesday, the agency’s highest screening volume since March 16.

Those travelers still represented fewer than half of the 2.6 million screenings that TSA agents conducted on the day before Thanksgiving last year. Combined with auto and rail, AAA predicted that as many as 50 million Americans will have been on the move by the end of the weekend, raising concerns that coronavirus cases will continue to flare in the coming weeks.

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With some states and big cities suspending reporting of new cases for the holiday, many medical experts predict that the country will not know until next week just how rapidly the virus is spreading. By Thursday evening, however, the United States had already reported more than 127,000 new cases and more than 1,300 additional deaths from those locations that continued to report data.

On Tuesday and Wednesday, the nation topped 2,000 deaths for the first time since May 6. Wednesday was the 33rd consecutive day the United States set a record in its seven-day average of reported cases, according to data compiled by The Washington Post. Nearly 90,000 people are in hospitals with covid-19, the illness caused by the coronavirus, another record.

As has been largely the case since the Nov. 3 election, President Trump mostly kept quiet amid the deepening crisis on Thanksgiving, except to applaud the 5-to-4 Supreme Court decision that blocked limits on religious worship services in coronavirus hot spots that had been imposed by New York Gov. Andrew M. Cuomo (D).

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“HAPPY THANKSGIVING,” Trump wrote on Twitter early Thursday while referencing the court decision, which was reached after new Justice Amy Coney Barrett sided with four other conservative justices.

Later in the day, Trump issued a Thanksgiving proclamation that compared Americans’ battle against the virus to adversity that European settlers faced 400 years ago.

“We have leveraged our strengths to make significant breakthroughs that will end this crisis,” the White House statement said, referring to “groundbreaking therapeutics and life-saving vaccines.”

President-elect Joe Biden, meanwhile, released a video in which he and his wife, Jill, called on Americans to stick close to home during the holiday. The Bidens also called on the nation to remember the more than 262,000 Americans who have died from covid-19.

“We might not be able to join our hands around a table with our loved ones, but we can come together as a nation,” the president-elect said. “I know better days are coming.”

But on Thursday, confusion and new questions persisted about the vaccine that pharmaceutical company AstraZeneca is developing with the University of Oxford, which is viewed as one of three early candidates for FDA approval.

AstraZeneca said Monday that its vaccine was 70 percent effective overall, with the most hopeful segment of data — a 90 percent effective vaccine — reported in a group of fewer than 3,000 people who received only half the initial dose of the two-dose regimen. The full two-dose regimen, the one being tested in a large clinical trial in the United States, was 62 percent effective.

Although the vaccine appeared less efficacious than candidates being developed by Moderna and jointly by Pfizer and BioNTech, the news was welcomed by physicians and scientists. The AstraZeneca vaccine appeared effective and had advantages — it is less expensive and easier to distribute because it can be stored long-term at standard refrigerator temperatures.

Then, a company executive late Monday disclosed to Reuters that the half-dose regimen wasn’t planned. Instead, it was an error that was noticed when participants who received that dose reported fewer of the short-term reactions that were expected, such as a sore arm or fatigue.

That news, arriving hours after company leaders and Oxford scientists disclosed results without mentioning the stumble that led to the half-dose regimen, raised criticism about a lack of transparency and questions about whether the 90 percent results would hold up.

The company has not disclosed details of the 131 study participants who developed covid-19, including whether they received a placebo or the vaccine. Such data is pivotal in understanding the effectiveness of a vaccine.

“It’s very confusing at this point,” Ira Longini, a biostatistician involved in vaccine trials at the University of Florida, said in an email. “We need to see all the numbers. . . . It’s not good statistical practice to publicly release ad hoc calculations without a completely transparent presentation of all the results.”

The next day, Moncef Slaoui, scientific leader of Operation Warp Speed, the Trump administration’s vaccine effort, disclosed that people older than 55 were not included among the study participants for whom the vaccine proved 90 percent effective. Older people are considered crucial to study because they are at elevated risk for severe illness from the coronavirus. He added that the two efficacy results were “overlapping statistically,” making it possible, though unlikely, that random chance could account for the difference.

“We need to understand what’s behind it scientifically,” Slaoui said.

AstraZeneca chief executive Pascal Soriot told Bloomberg News that the company would probably run a new trial to test the half-dose regimen, but added that the new trial is not expected to delay regulatory approval in the United Kingdom and the European Union.

“Now that we’ve found what looks like a better efficacy, we have to validate this, so we need to do an additional study,” Soriot said.

At an evening news conference in London, Patrick Vallance, the British government’s chief scientific adviser, said he remained optimistic that the vaccine was still on track for final scrutiny from government regulators.

“Headline results: This vaccine works, and that’s very exciting and it’s going to be put forward for approval,” Vallance said. “The regulators will need to look at it and decide, and that will be true for all of the vaccines.”

David Benkeser, a biostatistics expert at Emory University’s Rollins School of Public Health, said in an email that remaining questions about the vaccine could be answered by modifying the ongoing trial in the United States.

“The more details I hear about these trials, the more challenging their interpretation gets,” Benkeser said. “But overall, the results are still encouraging. A vaccine with 60 to 70 percent efficacy, a good safety profile, tenable cold chain, and inexpensive manufacturing costs is still, by all accounts, a good vaccine.”

Even amid widespread speculation that the FDA could approve at least one of the vaccine candidates before Christmas, the Centers for Disease Control and Prevention and state health departments braced for deaths to increase in the coming weeks.

One model used by the CDC projects a death toll of more than 3,000 people a day by the third week of December, when the nation is likely to eclipse 300,000 total deaths since the pandemic began.

The nation’s governors have cited the rising death toll — and concerns about a critical shortage of hospital intensive care beds — as one reason they are issuing new orders to try to slow the spread of the virus.

In Pennsylvania, Gov. Tom Wolf (D) took the unusual step of shutting down liquor sales in bars and restaurants the night before Thanksgiving, effectively eliminating one of the biggest bar nights of the year.

On Thursday morning, Cuomo blasted the Supreme Court’s new conservative majority for ruling against his restrictions on religious gatherings, even as he stressed that the ruling is not a final legal decision because the matter will be passed down to an appeals court.

“I think this was really just an opportunity for the court to express its philosophy and politics. It doesn’t have any practical effect,” Cuomo said. “I fully respect religion, and if there’s a time in life when we need it, the time is now, but we want to make sure we keep people safe at the same time.”

New York did try to offer the nation one semblance of normalcy. The annual Macy’s Thanksgiving Day Parade was broadcast nationally, although the parade was confined to just one block and some of the show was taped beforehand.

There were no visible spectators, but the parade ended with the traditional arrival of Santa Claus and Mrs. Claus.

Santa did not wear a mask, while Mrs. Claus waved to the camera while wearing a face covering.

Karla Adam and Paulina Villegas contributed to this report.

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