Health workers in protective gear peer from a tent which was constructed to test people for the coronavirus disease (COVID-19) outside the Brooklyn Hospital Center in Brooklyn, New York City, March 27. — REUTERS/ANDREW KELLY

JEFF JENSEN, a critical-care doctor in Rochester, Minnesota, volunteered last spring to bolster New York City’s medical workers during its coronavirus disease 2019 (COVID-19) crisis. The 51-year-old spent two weeks in an ad hoc intensive-care unit at a Brooklyn public hospital.

Now, the pandemic rages in Jensen’s own back yard, but he expects no reinforcements. A nationwide surge of the virus threatens to overwhelm America’s health-care workforce.

“We haven’t extended the request, but I’m confident that there’s no one that could come to help,” said Jensen, who splits his time between Mayo Clinic Rochester and Mayo Clinic Health System in La Crosse, Wisconsin. “They would be busy taking care of the local issues in their community.”

Earlier waves of the pandemic were geographically concentrated: the Northeast in the spring, then Florida, Texas and Arizona in the summer. Today’s cases and hospitalizations are widespread, increasing in 49 states in the past week. COVID cases are reaching records in the US, with the seven-day average climbing to a high of 134,197 Thursday, according to Johns Hopkins University data. One-in-5,000 Americans is currently hospitalized with the virus, the most ever in data aggregated by the Covid Tracking Project.

Without enough workers to care for the ill, hospitals will face brutal triage decisions about which patients can be saved. They may run out of space, forcing the sick to suffer in hallways and improvised intensive care units. And the months of psychic strain on doctors and nurses will redouble.

“Right now, it’s bad everywhere,” said Pete Aftosmes, a vice president at Premier, Inc., which provides purchasing, technology and consulting services to more than 4,000 hospitals. “It’s getting pretty dire at this point.”

Health systems are seeing higher turnover and attrition, and more vacant positions that take longer to fill. Before the pandemic, Premier’s clients typically had 2,500 open requests for clinical staff. That grew to about 9,000 this year, and recently spiked to almost 20,000.

Demand is highest for nurses, who make up the largest part of the clinical workforce. As a result, pay rates are increasing for those willing to travel to areas with the highest demand. Aftosmes said some hospitals are paying as much as $80 to $150 an hour to fill nursing positions. The typical hourly wage for registered nurses is about $35.

Several factors have diminished the supply of clinicians. Some nurses with children can’t work while schools are closed or choose to stay home because they care for elderly relatives at risk for the virus. Others near the end of their careers have opted for early retirement rather than risk exposure.

Staff are also out sick with COVID-19 or quarantining after being exposed. In one health system Premier works with, Aftosmes said 30% of the clinical staff was sidelined for those reasons.

National data on labor constraints at hospitals is hard to find, but information from states and anecdotal reports show it’s putting a ceiling on hospital capacity.

In Minnesota, the number of available beds reported to the state has fluctuated, with some signs of recent declines, according to data analyzed by the COVID-19 Hospitalization Tracking Project at the University of Minnesota’s Carlson School of Management. Intensive-care beds showed a similar drop.

Hospitals report their capacity in “staffed beds” — not just the number of physical beds, but the number that they have workers to operate. The changes in Minnesota likely reflect staff on hand, said Archelle Georgiou, one of the leads on the tracking project. “Certainly beds don’t disappear,” she said.

Having fewer nurses, doctors, respiratory therapists and other clinicians can hurt patient care, said Carlos del Rio, executive associate dean at Emory School of Medicine and Grady Health System in Atlanta.

Intensive-care units typically have a ratio of one nurse for two patients. With a lot of patients and not enough staff, he said, nurses might take on four or five patients. “The moment you do that, the quality of care goes down,” he said.

There’s an $18 billion market for health-care staffing, with travel nurses and other professionals taking temporary assignments. Hospitals in rural areas or markets where they have trouble getting people to permanently relocate are particularly reliant on travel staff.

The country’s largest health-care staffing agency, AMN Healthcare Services, Inc., is seeing record demand for nurses. Health systems “are dealing with increasing worker burnout, unanticipated attrition, and the needs of health-care professionals to have time off, after months of stress and strain,” AMN Chief Executive Officer Susan Salka told analysts this month.

Vacancy rates that would typically be around 5% are now closer to 10%, said Landry Seedig, an executive who leads the nursing and allied solutions business at AMN Healthcare. Some hospitals are offering double pay for overtime or bonuses to get the staff they need. “The intent is to attract nurses by paying top dollar,” Mr. Seedig said in an interview. And the need is urgent. “They’re not asking for a nurse four weeks from now,” he said. “They’re asking for a nurse to get here tomorrow.”

Hospitals across the Midwest and West have begun to take steps to preserve capacity as COVID-19 admissions mount.

In North Dakota, Governor Doug Burgum suggested this week that asymptomatic nurses who test positive for COVID-19 could continue to care for Covid patients. The North Dakota Nurses Association resisted, saying the policy wasn’t a long-term fix for shortages.

Federal medical teams have supported hospitals and long-term care facilities in Wisconsin, Montana, Minnesota and Texas in recent weeks. Hospitals in Oregon, Missouri, Illinois, Ohio and Iowa have begun postponing some elective surgeries, according to local media reports.

Health systems in Michigan warned they may have to do the same. Governor Gretchen Whitmer said Covid patients are expected to double in two weeks and at the current rate some hospitals will run short of protective gear. 

Some worry what the coming wave of COVID hospitalizations will do to a labor force that’s already worn down from months of treating virus patients, sometimes with inadequate supplies. Even before the pandemic, rates of burnout among health-care workers were high.

“There is cause to be concerned about this workforce,” said Katie Boston-Leary, nursing practice and work environment director at the American Nurses Association. Some nurses, she said, “never really took a breath. In some cases, there wasn’t really a lull. The COVID cases never stopped.”

It’s poised to get worse. With COVID cases on the rise everywhere at once, the country doesn’t have the cushion it had in the spring and summer, Ms. Boston-Leary said.

“This is different,” she said. “This is scary.”

Mr. Jensen, the Minnesota doctor, said the effect of exhaustion and infections occurring in the community is evident.

“We just don’t have enough nurses or nurses’ assistants to take care of patients,” he said. “Not just COVID patients, but patients in general.” — Bloomberg