The United States appears to have avoided the worst-case coronavirus scenarios that officials feared would overwhelm hospitals in the aftermath of Christmas and New Year’s gatherings. But experts caution that the threat from the virus has not diminished and could intensify with the emergence of new variants.

Even as hospitalizations begin to stabilize, they do so from record heights. The country’s hospitals averaged more than 130,000 covid-19 patients a day over seven days this month, far exceeding summer and spring surges. The death toll from cases contracted before and after the holidays will stretch into February. Authorities reported nearly 4,500 deaths Wednesday, a new single-day record.

Cases skyrocketed at the start of 2021, approaching a seven-day daily average of 250,000 around Jan. 10 before declining. But the toll on the health-care system was softer than expected.

Hospitals had braced for enormous spikes in patients that could have forced rationing care, exhausted already limited beds and sparked a nationwide shortage of health-care workers. But officials across the country said those dire predictions — a wave of severe Christmas cases weeks after a rapid increase from Thanksgiving — did not materialize in most places.

“The surge on top of a surge that could have happened didn’t really happen,” said Erin Bromage, a biology professor at the University of Massachusetts at Dartmouth. “We dodged a bullet, and we’ve done better than we could have, but we are still in a pretty terrible spot.”

Anthony S. Fauci, the nation’s top infectious-disease expert, said at a White House briefing Thursday that cases appeared to be plateauing, but he warned that it could be a temporary slowdown.

On Jan. 20, Anthony S. Fauci, the nation's top infectious disease expert, reflected on his time under former president Donald Trump. (The Washington Post)

Hospital leaders and experts are still on edge. Variants of the coronavirus, including the B.1.1.7 strain, which originated in the United Kingdom and is believed to be 50 to 70 percent more contagious, could result in further case spikes in cold-weather months, when people are more likely to be indoors. And the availability of the coronavirus vaccines, while offering lifesaving protection to millions, could also lead to a false sense of complacency, particularly as they can be difficult to obtain.

“It’s like a pot of boiling water, so the temperature may have been turned down some, but it’s still dangerously hot,” said Carmela Coyle, chief executive of the California Hospital Association. “Plateauing is not a good thing.”

Infections soared in the aftermath of Thanksgiving, leading some to fear an even greater surge after back-to-back Christmas and New Year’s celebrations, where people would gather with family and friends, then travel back home, potentially spreading the virus with each step. The Transportation Security Administration recorded its highest number of airline travelers since the pandemic began around Christmas, exceeding 1 million daily.

Experts have floated several theories for why the holiday season dealt less damage than expected. Some people may have changed their behavior after seeing the Thanksgiving spike, such as by celebrating outdoors, limiting gatherings to immediate family or quarantining before Christmas. More people who have contracted the virus could be receiving treatment at home while the sickest patients are hospitalized.

Robert Kaplan, a medical professor at Stanford University who was among those raising alarms about a holiday surge, said hospitalizations appear to be dipping in states that already had high caseloads and rising in those that had lower caseloads.

“There may be some places in the country where there are fewer people eligible to get sick, because they’ve already been infected,” Kaplan said.

Los Angeles County faces one of the worst crises, with officials taking steps to conserve oxygen needed to treat covid-19 patients struggling to breathe and 11 percent of intensive care beds still available.

Researchers and county health officials released new projections Wednesday offering some good news: Hospitalizations have leveled off with enough ventilators to treat patients, and declines in admissions are projected, even under conservative estimates.

The bad news: Even with declining caseloads, the stress on hospitals will be so high that bed shortages will continue. Those who have been admitted are coming in with more severe cases of covid-19 and are more likely to die.

About 1 in 8 hospitalized covid-19 patients in Los Angeles died from September to November — a figure that doubled to 1 in 4 after Nov. 3.

Roger Lewis, who leads the Los Angeles County Department of Health Services modeling team, said the figures suggest hospitals are being more selective in whom they admit.

“With that level of hospital demand, clinicians are forced to be very careful to reserve hospital resources for patients who clearly need it to ensure that resource is available to those whose life depends on it,” Lewis said. “Decisions are being made now to send people home with instructions to come back rather than admitting as a precaution.”

Nicholas Testa, chief physician executive of Dignity Health, which operates four hospitals in Los Angeles County and two in neighboring San Bernardino County, said the hospitals experienced a Christmas surge, with admissions peaking 15 days after the holiday. He said the health system managed the increase in part because the lengths of stays have been shorter, and county and state officials have offered additional resources. Still, hospitals teetered on the brink of rationing care.

“We got as close to the edge of care as I ever want to be,” Testa said. “When you get to what’s called crisis care is when you have to start making decisions about [who gets] ICU beds and ventilators. We did not get to that point, thank God. It came pretty darn close.”

The American Hospital Association says others reported similar experiences.

“No one should be fooled that we are in an easy period right now,” said Nancy Foster, the group’s vice president for quality and patient safety policy. “The cold, hard data says we were on the brink in many places, many communities across the country.”

California appears to be in a stronger position statewide as Northern California avoids the brunt of crisis. Mark Ghaly, the state’s top health official, on Tuesday hailed an 8.5 percent decline in hospitalizations and 2.8 percent decline in ICU admissions over two weeks as a sign that the post-holiday surge was “not as bad” as projected.

President-elect Joe Biden attended a vigil for coronavirus victims the evening before his inauguration on Jan. 19. (The Washington Post)

Arizona has been another major coronavirus hot spot, reporting the nation’s highest per capita rates of new cases, hospitalizations and deaths through January. The hospitalization rate now stands at 65 per 100,000 residents, a slight decline from the start of the month.

Marjorie Bessel, chief clinical officer for Banner Health, Arizona’s largest health system, said the Jan. 11 peak, even if lower than expected, left hospital workers toiling in crowded conditions under enormous stress. Hospitals forced patients to share their rooms and repurposed labs and other areas, while corporate office staff were redeployed to the front lines.

“Yes, it could have been worse, and yes, it could have been better if there was more mitigation and more enforcement of mitigation,” said Bessel, who has criticized Gov. Doug Ducey (R) for declining to implement new restrictions to slow the virus’s spread. “Let’s just hope the worst is truly behind us, and we can continue to spend the next many, many months recovering from what we just went through.”

Parts of the country that weren’t as hard hit as the southwest heading into the Christmas season avoided a new crisis.

“We’re past the surge that could have come from Christmas and New Year’s,” Illinois Gov. J.B. Pritzker (D) said recently after lifting restrictions. “I say that with some trepidation, because you know, there’s always the possibility that we’ll see an upsurge from that. But I think with one incubation period past New Year’s Day, New Year’s Eve, our numbers look like good news.”

Louisville Mayor Greg Fischer (D) told residents at a recent town hall that hospitals avoided “extreme stress” in the holiday aftermath. In an interview, he said weekly cases hit 4,100 last week, a slight increase from a previous high, but the newly infected were disproportionately young and less likely to be hospitalized.

“We are seeing case counts spike, but we are not seeing a massive run to the hospitals,” Fischer said.

In Pennsylvania, the University of Pittsburgh Medical Center system prepared for hospitalizations across all of its facilities to approach 3,000 in January, more than twice the 1,200 mid-December peak. Instead, they have been declining to about 600 this week — a potential sign that residents learned lessons after a Thanksgiving spike.

“We prepared for the worst, but we deal with what exactly the realities are today,” said Donald Yealy, senior medical director at the system. “I would not be surprised if there was one final increase left. I don’t expect covid-19 infection and illness to just evaporate.”

About 3,900 deaths were reported Friday in the United States, suggesting Wednesday’s peak may not be an anomaly. The seven-day average of deaths in the weeks after Thanksgiving hovered around 2,500.

“We are getting, in some way, numb to the numbers,” said John Brownstein, chief innovation officer at Boston Children’s Hospital. “The numbers of hospitalizations, cases and death are still incredibly high. Even if we see a pullback, those numbers are still incredibly scary.”