At a rural health system in Wisconsin, officials and medical experts began drawing up protocols for the once unthinkable practice of deciding which patients should get care. The chief quality officer of a major New York hospital network double- and triple-checked his system’s stockpile of emergency equipment, grimly recalling the last time he had to count how many ventilators he had left. In Arizona, a battle-weary doctor watched in horror as people flooded airports and flocked to stores for Black Friday sales, knowing it was only a matter of time before some of them wound up in his emergency room.

Days after millions of Americans ignored health guidance to avoid travel and large Thanksgiving gatherings, it’s still too soon to tell how many people became infected with the coronavirus over the course of the holiday weekend. But as travelers head home to communities already hit hard by the disease, hospitals and health officials across the country are bracing for what scientist Dave O’Connor called “a surge on top of a surge.”

“It is painful to watch,” said O’Connor, a virologist at the University of Wisconsin at Madison. “Like seeing two trains in the distance and knowing they’re about to crash, but you can’t do anything to stop it.”

“Because of the decisions and rationalizations people made to celebrate,” the scientist added, “we’re in for a very dark December.”

The holiday, which is typically one of the busiest travel periods of the year, fell at a particularly dire time in the pandemic. Some 4 million Americans have been diagnosed with the coronavirus in November — twice the previous record, which was set last month. More than 2,000 people are dying every day. Despite that, over a million people passed through U.S. airports the day before Thanksgiving — the highest number of travelers seen since the start of the outbreak.

Many states did not report new case counts over the holiday, and it typically takes about a week for official records to catch up after reporting delays, said Caitlin Rivers, an epidemiologist at the Johns Hopkins Center for Health Security.

But in two to three weeks, she said, “I fully expect on a national level we will see those trends continue of new highs in case counts and hospitalizations and deaths.”

The nation has already notched several bleak milestones over the holiday weekend. On Thanksgiving Day, hospitalizations in the United States exceeded 90,000 people for the first time. The following day, the country hit 13 million cases. At least nine states have seen 1 in every 1,000 residents die of the coronavirus.

Mark Jarret, the chief quality officer for New York’s Northwell Health system, said he understood that many people are tiring of constant vigilance after nine months of isolation and Zoom gatherings and waving at people from six feet away.

“But we’re so close to getting some control,” he said, noting that federal officials are on the verge of authorizing one or more vaccines against the virus next month. “This is not the time to let up. This is the time to put on the best defense we can to prevent further spread, further death.”

Officials urged people who traveled or spent time with people outside their household to stay at home for 14 days to avoid further spread of the virus. Some jurisdictions are moving toward lockdown measures not seen since the spring. Los Angeles County on Friday issued a three-week “safer at home” order, limiting business capacity and prohibiting gatherings other than religious services and protests.

Meanwhile, the December holidays are looming.

“Hopefully people will try to minimize their risks around Christmas, especially if there’s data that show Thanksgiving was really harmful,” O’Connor said.

To Cleavon Gilman, a Navy veteran and emergency room doctor in Yuma, Ariz., the wave of holiday travel was “a slap in the face.”

“It’s as if there’s not a pandemic happening,” he said. “We’re in a war right now, and half the country isn’t on board.”

On Friday, members of the University of Arizona coronavirus modeling team issued an urgent warning to state health officials, projecting that the state will exceed ICU capacity by the beginning of December.

“If action is not immediately taken, then it risks a catastrophe on a scale of the worst natural disaster the state has ever experienced,” the team wrote in a letter to Steven Bailey, chief of the Bureau of Public Health Statistics. “It would be akin to facing a major forest fire without evacuation orders.”

Arizona has no statewide mask mandate, and businesses in many parts of the state, including indoor dining at restaurants, remain open.

Gilman said the intensive care unit at his hospital is full and there’s nowhere to transfer new patients. When he’s home, his mind echoes with the sound of people gasping for breath. He and his colleagues are exhausted, and with cases spiking across the country, he worries there is no way they can handle the surge that will probably follow Thanksgiving celebrations.

In La Crosse, Wis., Gundersen Health System chief executive Scott Rathgaber echoed that fear. “We’ve had to tell our hard-working staff, ‘There’s no one out there to come rescue us,’” he said.

Like many in his college town, Rathgaber is anxious about what will happen when students who spent the holiday with their families return to campus. Though the University of Wisconsin and other schools shifted classes online for the remainder of the semester, he anticipates students who have jobs and apartments in La Crosse will return to town.

“We had trouble the first time the students came back,” Rathgaber said, noting that the start of college classes in September preceded outbreaks in nursing homes and a spike in deaths in La Crosse County. “I will continue to implore, to beg people to take this seriously.”

Gundersen has already more than tripled the size of the covid-19 ward at its main hospital, and even before this week it was almost entirely full. Physicians from the system’s rural clinics have been reassigned to La Crosse to help in the ICU. Staff who may have been exposed to the virus are being called back before completing their 14-day quarantine. And Rathgaber now attends regular meetings with ethicists and end-of-life caregivers to figure out Gundersen’s triage protocol if the hospital becomes overwhelmed.

“We’re not at a breaking point, but we are getting there,” Rathgaber said. “I’m concerned about what the next two weeks will bring.”