Dozens of health-care workers have fallen ill with covid-19, and more are quarantined after exposure to the virus, an expected but worrisome development as the U.S. health system girds for an anticipated surge in infections.

From hotspots such as the Kirkland, Wash., nursing home where nearly four dozen staffers tested positive for the coronavirus, to outbreaks in Massachusetts, Pennsylvania, California and elsewhere, the virus is picking off doctors, nurses and others needed in the rapidly expanding crisis.

“We all suspect it’s the tip of the iceberg,” said Liam Yore, a board member of the Washington state chapter of the American College of Emergency Physicians.

EvergreenHealth in Kirkland, Wash. has already seen more than 100 cases of COVID-19. Their ICU director explains how they are working to save lives. (Tim Matsui/The Washington Post)

“The risk to our health-care workers is one of the great vulnerabilities of our health-care system in an epidemic like this,” he said. “Most ERs and health-care systems are running at capacity in normal times.”

Gauging how badly providers have been hit is difficult because no nationwide data has been released by the Centers for Disease Control and Prevention, medical associations or health-care worker unions. A federal official who was not authorized to talk with the media, and so spoke on the condition of anonymity, said the government has received reports of more than 60 infections among health-care workers. More than a dozen are related to travel. Authorities are investigating how the others happened.

In previous outbreaks of infectious disease, and in other countries where the current pandemic arrived earlier, health-care workers have experienced a disproportionate share of infections. They have been put at risk in the United States not only by the nature of their jobs, but by shortages of protective equipment such as N95 face masks and government bungling of the testing program, which was delayed for weeks while the virus spread around the country undetected.

At the EvergreenHealth hospital in Kirkland, Wash. — just a few miles from the nursing home at the center of the U.S. outbreak — and in Paterson, N.J., two emergency physicians are hospitalized in critical condition with covid-19, according to their professional association. It is unclear whether the doctors, in their 40s and 70s respectively, were infected at their hospitals or in their communities, the American College of Emergency Physicians said.

“As emergency physicians, we know the risks of our calling,” the group’s president, William Jaquis, said in the statement.

In Pittsfield, Mass., 160 employees of Berkshire Medical Center have been quarantined at home after exposure to patients who tested positive, forcing the medical center to hire 54 temporary nurses, who began arriving Friday, according to news reports.

A providerhas tested positive at Johns Hopkins Hospital in Baltimore. In another case, a former employee ofNYU Winthrop Hospital in Mineola, N.Y., flew from New York to Florida last week while awaiting results of a coronavirus test that ultimately showed he was infected, a spokeswoman told The Washington Post. In Philadelphia, St. Christopher’s Hospital for Children shut its intensive-care unit to new patients and closed a trauma unitafter a physician tested positive, the Philadelphia Inquirer reported.

Bonnie Castillo, head of the 150,000-member National Nurses United, the largest nurses union, said the shortage of protective equipment is the most critical issue for those workers.

“Nurses take risks every day because they’re willing to do that, they’re called to do that, and they want to do that,” she said. “When you’re being sent out there with one of the most highly contagious viruses without your tools and your weapons and without a coordinated plan, it’s frightening.”

Caregivers outside hospitals and nursing homes may be even more vulnerable.

A 36-year-old firefighter and emergency medical technician in Santa Cruz, Calif., was denied a test early this month because he didn’t meet the strict government criteria then in force. He tested positive for the virus late last week.

“This, to me, was the failure of the public health system,” said his wife, who also has tested positive and spoke on the condition of anonymity because she fears that her family will be unfairly blamed for exposing others. “This was a decision made because there weren’t enough tests to prioritize my husband.”

On March 9 the couple learned that one of the EMT’s co-workers had tested positive after being hospitalized. At that point, based on their contact with someone with a confirmed infection, they both were tested.

“As EMTs, they are going into these vulnerable communities, going into convalescent homes, literally responding to and interacting with the most vulnerable people,” she said.

Eight firefighters in nearby San Jose also have tested positive for the virus in recent days, according to news accounts. In Kirkland, 42 of 100 members of the fire department and a few police officers were quarantined, some after responding to 911 calls from the Life Care Center nursing home.

Others caught the virus as it spread through the community, said a spokeswoman for the city. Five firefighters remained in quarantine Monday, and one has tested positive for the virus.

A Life Care health worker in her 40s was one of the first known people to test positive in Seattle’s King County, as public health officials announced Feb. 29. A third of the 180-member staff remained out Friday with covid-19 symptoms, said Timothy Killian, a Life Care spokesman.

King County officials said Tuesday that a county public health staffer involved in the coronavirus response has tested positive. But officials warned that hundreds were already infected, and “we can expect that anyone we come into contact with may be infected because there is wide-spread infection in our community.”

“It’s critical to minimize the number of people who get seriously ill at the same time,” county health officials said in a statement. “If too many people get sick all at once, this will put too much of a burden on our health care system. If that happens, people at highest risk — people over 60, and with underlying health conditions — may not be able to get the care they need if they get seriously ill.”

Because testing has lagged,health-care workers often have no way to know whether people walking through the door with respiratory symptoms are suffering from the flu or covid-19, providers said. Even when precautions are taken, the virus has found its way into health-care facilities.

At a Veterans Affairs hospital in Tucson, 23 people with respiratory symptoms were brought to an outpatient clinic with no protections for staffers except masks, said a doctor who works at the facility. She spoke on the condition of anonymity because she is not authorized to discuss care with the news media.

“They’re not doing the testing,” she said. “They marched them through the hospital to my clinic. They put masks on them but nothing else.”

Marcelo Venegas, a doctor at an urgent-care center in Queens, woke up Thursday morning with symptoms consistent with covid-19, including shortness of breath and a low-grade fever. His flu test came back negative, and a coronavirus test is still pending. He is now is quarantined at home in Teaneck, N.J., until at least Friday.

Venegas saw two patients with confirmed covid-19 infections and more than a dozen others whom he suspected had the virus. Many were under 50 and had negative tests for the flu. Venegas said he wanted to test at least 20 people for coronavirus but didn’t bother because he knew they would not fit the tight eligibility criteria.

He said he’d called in sick only twice before in eight years on the job. “Being sick is daunting,” he said. “I’m never sick.”

During Monday’s briefing on the pandemic, Vice President Pence stressed that health-care workers and people older than 65 would receive priority as the government increases the number of testing sites.

“We’re putting a real priority on our extraordinary health-care workers,” Pence said.

But the risks of caring for infectious, seriously ill people under the pressure of a pandemic are almost impossible to avoid. In hard-hit Italy, for example, 20 percent of health-care professionals in the Lombardy region have become infected with the virus, according to an update Friday in the Lancet medical journal. In China, 3,387 health-care workers were infected by Feb. 24, almost all in Hubei province, the center of the outbreak, according to Chinese health authorities.

In the 2003 SARS outbreak in Toronto, most cases were acquired in hospitals. Of the 44 people who died, two were nurses and one was a doctor. During the Ebola outbreak of 2014-2016, more than 8 percent of Liberian health-care workers died.

“If there are large numbers of health-care workers exposed, how do we manage that and keep them out of health-care facilities?” asked former CDC director Tom Frieden. “. . . You eliminate your ability to respond.”

Lena H. Sun contributed to this report.