Always overworked and underpaid, now more than ever, how we treat our healthcare workers will define the nation’s survivability of the coronavirus crisis.

The global wave of Covid-19 is about to crash all over the country—and the weak point in what happens next is the nation’s healthcare workers. Or rather, the health of the nation’s healthcare workers.

The collision of two problems—the slow roll-out of tests for the virus and low supplies of face masks and other protective gear—have left hospital officials unable to say for sure how many nurses, physicians, and other employees might already have been exposed via contact with patients. That has led to hundreds of healthcare workers being sent home for just-in-case quarantines. This has added stress to already overworked medical systems in the states that first experienced community transmission, including Washington, California, Massachusetts, and New York.

Experts in preparedness and infection prevention are worried about maintaining a delicate balance during this expanding crisis, trying to keep healthcare workers safe without depriving hospitals of so many workers that they cannot care for the patients who are coming their way.

“Hospitals are already short-staffed, and we are in a severe flu season,” says Saskia Popescu, an epidemiologist and infection-prevention specialist at HonorHealth in Phoenix. “We have to be practical about what we can and can’t do.”

During the last global virus epidemic, caused by the SARS virus in 2003, 21 percent of the victims were healthcare workers.

Just last week, Berkshire Medical Center, a 300-bed hospital in western Massachusetts, was forced to send home more than 50 of its 800 nurses, after they were exposed to the hospital’s first Covid-19 patient. And scenarios like that are now playing out all over the country.

Healthcare workers are being sent home because the CDC’s strict testing guidelines and the low availability of the kits themselves mean they also can’t be tested. Without a test, and with Covid-19 research just getting started, there’s no way to know whether this move will prevent them from spreading a serious illness—or compel them to spend 14 days on an unwanted vacation from an institution that really needs them.

Exacerbating the problem is that there is not enough protective gear to go around to keep healthcare workers on the job, because most masks and gowns come from China and India, and there those supply line have been effectively cut off.

Infection prevention has a dual role in hospitals: It keeps health care workers safe, and it also keeps them from inadvertently carrying pathogens from one patient to another. Wearing all the gear keeps them from being infected, and swapping out each piece of equipment every time they come out of a patient’s room keeps down pathogen transport.

But that adds up to a lot of masks, gowns, goggles, and gloves. So some people at health care institutions are rethinking the balance between those two tasks, evaluating whether some gear can be worn longer without incurring greater risks. Experts in Singapore, which reformed its health care system after SARS, have thought through the possibilities. Eli Perencevich, an infectious-disease physician and professor at the University of Iowa Carver College of Medicine and the Iowa City Veterans Administration says. “We’ve learned from Singapore colleagues that it’s possible to keep an N95 respirator and goggles on for a few patients, possibly even a full shift if they are not contaminated.”

The Trump administration says it will be making such gear available to state governors from strategic emergency contingency supplies, and will mandate increased domestic production, but is the move too little too late?

“All of this takes time,” Perencevich says, “It takes weeks to prepare for this. And my theory is that some places don’t have weeks.” But how well hospitals protect their health care workers will be crucial in determining how well or badly American medicine handles Covid-19, when the coming wave breaks.