The number of Americans hospitalized with covid-19 reached more than 126,000 this week — the highest level in a year. But this wave of the pandemic looks different from what came before, with dueling variants on the move.

This time, a majority of patients counted as covid cases in some hospitals were initially admitted for other reasons, their covid infections discovered incidentally. And hospital staffs are stretched more than ever, with nearly 1 in 4 medical centers reporting this week they have a “critical” staffing shortage, the highest proportion of the pandemic.

In Los Angeles, where the fast-spreading omicron variant reigns, roughly two-thirds of covid patients in the county’s public hospitals were initially admitted for other causes, officials said Wednesday.

But at CoxHealth in Springfield, Mo., where officials say the older delta variant remains a ferocious threat, the coronavirus remains the immediate cause for 81 percent of covid hospitalizations.

“We are planning on a pretty scary scenario: volumes increasing and being short-staffed,” said Steve Edwards, the hospital’s CEO, warning that omicron could soon arrive and sicken his workers.

The latest coronavirus variant has taken over as the dominant strain in the U.S. Here’s what we know about omicron. (Monica Rodman, Sarah Hashemi/The Washington Post)

Many hospitals are reporting record surges of covid cases even as staff shortages hit their highest levels nationally during the pandemic, according to federal health data reviewed by The Washington Post — a one-two punch that is forcing hospitals to turn away ambulances, cancel procedures and warn would-be patients to stay away because they can’t promise prompt care.

While most hospitalized patients are adults, the number of pediatric covid inpatients has doubled since Christmas to a seven-day average of 3,800 children.

But the emerging picture varies dramatically from one region to the next, according to interviews with hospital leaders and health workers across 18 states. It ranges from omicron epicenters such as New York City, where many patients aren’t aware they’re infected until testing positive while visiting the hospital for other procedures, to Michigan and Minnesota, where health workers continue to treat patients fighting for survival against the more severe delta variant.

The Centers for Disease Control and Prevention projects that delta may have accounted for as much as 41 percent of covid cases across parts of the Midwest last week and as little as 1 percent of cases in Texas and surrounding states, although the CDC has repeatedly revised its national map of variant spread in recent weeks, struggling to keep up with the fast-moving omicron.

In Rhode Island this week, 54 percent of hospitals reported a “critical” staff shortage. But just 20 percent of Florida and Texas hospitals reported similar shortages, according to data collected by the Department of Health and Human Services.

Around the nation, front-line workers said the surge of cases and hospitalizations — coupled with the continued frustration of treating patients who refuse to get vaccinated or who berate health workers for encouraging them to take protections — has left the system vulnerable to the omicron wave, particularly because the delta variant never really left.

“It’s putting a further strain on an already incredibly strained nursing workforce,” said Kevin Romanchik, an emergency room and critical care nurse who works for the University of Michigan Health System, warning that the rising demands are “directly impacting our ability to care for patients in a safe manner.”

The fragile situation has prompted dozens of health-care organizations to take out full-page newspaper ads in Illinois, Minnesota and Wisconsin begging residents to get vaccinated, wear masks and take other precautions to avoid contracting covid.

“We now have more COVID-19 patients in our hospitals than ever before. And the overwhelming majority are unvaccinated,” read one ad sponsored by Cleveland-area health systems last month.

Just last summer, staff at several of those Cleveland health systems hoped they had nearly beat back the pandemic; at University Hospitals, the daily count of covid patients dwindled to a few dozen in July. But infections steadily rebounded, with 343 cases at the hospital by Dec. 14, driven by delta — and then jumped again, hitting an all-time high of 505 cases last week, as omicron raced through the region.

“We were coping with our delta surge, and omicron spread like wildfire,” said Keith Armitage, an infectious-disease doctor at University Hospitals.

Armitage said there were 486 covid patients in his hospital Wednesday, which he said represented “three buckets” of roughly equal size.

“First … patients admitted primarily due to an illness, covid-19,” Armitage said.

Second, “patients who have an underlying condition like heart failure, asthma, [chronic obstructive pulmonary disease], who get covid-19, which causes an exacerbation of their underlying condition,” Armitage said. “The third bucket is people who come in for something completely unrelated” and then test positive in the hospital.

The fact that patients are showing up at hospitals with other ailments and injuries only to test positive later for covid is another indicator that omicron causes less serious illness, especially in people who are vaccinated, experts say.

Armitage said he was heartened that omicron was leading to milder cases compared with prior variants, which he ascribed to more widespread access to vaccines and omicron’s more limited ability to attack the lungs. But Armitage warned that focusing on omicron’s relatively milder symptoms ignored the “net effect” of so many cases.

Given “how crowded the ER is, and how full the hospital beds are … the short-term concern on the health-care system is highly justified,” he said.

A changing picture

Hospitals are not required to publicly report how many patients are admitted with covid as the primary diagnosis, and many organizations contacted by The Post — including large, multistate health systems such as Dignity Health in the West, Advocate Aurora Health in the Midwest and Mayo Clinic, with campuses around the nation — said they had not been monitoring that breakdown or could not easily produce it. Hospital associations in Minnesota, Ohio, Vermont and other states also said they were not tracking why patients needed to be hospitalized for covid.

But amid omicron’s rapid advance, some hospitals have taken a fresh look at why patients are again filling their wards, trying to better understand the care and equipment necessary to fight the new surge, after earlier outbreaks sparked scrambles to find ventilators and secure other lifesaving interventions.

Katie Veron Taylor, medical director of infection prevention at Our Lady of the Lake hospital in Baton Rouge on Wednesday calculated that about one-third of the hospital’s 115 covid patients had asymptomatic or mild cases and had been admitted for unrelated reasons.

“Am I worried about those? Not really,” she said. “It does make me wonder how many incidental cases we had of delta, and I don’t think we were really focused on that back then.”

Jackson Health System in Miami on Wednesday announced that the hospital had 468 covid patients, although about 50 percent were admitted primarily for reasons not related to covid. The total caseload slightly exceeds the hospital’s prior peak of 445 covid patients in August, when the delta variant was surging in Miami-Dade County, hospital spokeswoman Lidia Amoretti wrote in an email — but nearly three-quarters of those patients were admitted primarily for covid.

Officials at CarePoint, which operates three hospitals in northern New Jersey, say their surge of covid patients has included a significant increase in those with secondary diagnoses. Such patients make up slightly less than half of patients on the hospitals’ wards. Some are completely unrelated, such as a girl who fell on a playground and broke her arm but tested positive with mild symptoms of covid.

As evidence has mounted that many people infected with omicron were initially hospitalized for other reasons, critics have argued that health-care leaders and federal officials have obfuscated why hospitalization numbers have risen in recent weeks.

“Looks like the conspiracy theorists who are now banned from Twitter were right all along, the official numbers were fake,” Tucker Carlson said on his eponymous Fox News show this week. “Those kids were in the hospital for broken bones and appendicitis, not covid.”

More than a dozen hospital leaders who spoke to The Post said much of the scrutiny over why covid patients are being hospitalized is misplaced.

“While it’s easy to say, oh, these admissions are not related to covid, it’s not quite the whole story,” said John Rimmer, CarePoint’s chief medical officer and emergency department director, adding that the virus may have worsened a preexisting medical condition such as asthma or diabetes, leading to patients’ hospitalization.

Rimmer and colleagues also listed examples of coronavirus-infected patients needing to be hospitalized at CarePoint — eventually. One older woman was admitted after she woke up in the middle of the night, dizzy from her coronavirus-induced fever, and then fell over, breaking her hip. A diabetic patient was hospitalized for high blood sugar after failing to take insulin while feeling sick from covid.

‘Finite resources’

The surging number of cases has collided with a separate trend: a worsening hospital staffing crunch that is exhausting workers, fueling rising staff turnover and leading to delays in care.

Hospitals have warned that more of their workers are falling ill with infections from omicron, constraining their capacity to care for patients. That prompted the CDC last month to accelerate the timeline for health workers to return after infections, saying that infected workers could return immediately in a “crisis” situation.

Meanwhile, nurse unions this week asked a federal appeals court to force the Occupational Safety and Health Administration to issue permanent workplace safety standards to protect health workers from covid, saying that some staff members have quit because they feel at risk.

“Ventilators, needles or syringes … those things can be ordered and restocked,” said Romanchik, the University of Michigan nurse. “Nurses and the care we provide are finite resources. We’re not just a number at the bottom line that you can replace.”

On Jan. 13, the Supreme Court blocked the Biden administration from enforcing a vaccination-or-testing requirement for large employers. Here’s what to know. (Julie Yoon/The Washington Post)

Health-care organizations throughout the nation have reported growing staffing challenges as the pandemic persists. Across the West, 28 percent of hospitals told federal officials they had critical staffing shortages this week — the region’s highest level of the pandemic. The Midwest (22 percent) and the Northeast (17 percent) also reported their largest shares of hospitals experiencing staffing crises since the start of the pandemic.

In Vermont, where 52 percent of hospitals reported a critical staffing shortage, the problem stemmed from a “crisis of rural health equity” that predated covid, one researcher said.

“Vermont entered the pandemic with long-standing workforce shortages, and the last several months have only exacerbated the challenges facing health systems,” said Anne N. Sosin, a health policy researcher at the Nelson A. Rockefeller Center at Dartmouth College.

Sosin said Vermont’s hospitals had persistently struggled to recruit specialists and other staff, and she was concerned that workers who quit during the pandemic could not be easily replaced.

“When we lose health-care workers from our rural region, it’s not clear that we’ll be able to fill those positions again,” she said.

But in Rhode Island — which reported the nation’s worst staffing shortage — health workers characterized the shortfalls as unprecedented.

“I’ve never seen this before, in the five years I’ve worked here,” said Brooke Huminski, a clinical social worker at Butler Hospital in Providence, R.I.

According to Huminski, the hospital had four social workers to assess patients in the hospital’s psychiatric emergency room during evening shifts — but after departures and an inability to find replacements during the past year, she’s the only one left.

“That’s created a problem — now the doctors need to pick up more of the work, which is interfering with patient flow … and of course, raising my own stress levels a bit,” she said.

Meanwhile, health workers are attempting to respond to the coronavirus surge even as the fast-spreading omicron variant encroaches on their personal lives. Huminski’s vaccinated 98-year-old grandfather was admitted to a hospital Tuesday after being diagnosed with covid for the first time.

“It’s a weird time to be worrying about him and also trying to function,” Huminski said.

Laurie McGinley contributed to this report.