“Because remember, we all did internships,” Swisher says. “We all did our rotations in medical school and you don’t forget this stuff, it’s like riding a bike in a lot of ways. We might be a little rusty at it.”

Instead of surgery, these doctors are spending their days in training sessions.

But these measures still may not be enough. Researchers believe prolonged exposure to the virus itself puts doctors at higher risk of becoming seriously ill, and hospitals need to plan more time off for front-line health care workers, says Dr. Ashish Jha, professor of global health at the Harvard T.H. Chan School of Public Health.

“Our best understanding of the high rates of infection is really because of a combination of inadequate PPE,” he says, referring to personal protective equipment like masks, gowns and gloves, “and fatigue and just long, long work hours. People start getting tired and they just end up being a little bit less vigilant and can make mistakes.”

This is especially worrying, he says, “because it creates a cascade where once health care workers start getting sick, everybody else has to work more hours, which increases their risk.”

Preventing this vicious cycle is going to be difficult. At San Francisco General Hospital, doctors who have a health condition that puts them at risk of becoming particularly ill from COVID-19 are encouraged to stay home. Current contingency plans for filling the gaps as others become ill generally involve other physicians working more hours.

“People are volunteering their extra time to be part of the backup system, should residents get sick,” says Grace Taylor, a third-year resident doctor in the ER.

“We're talking about changing the length of people's shifts,” she adds, to allow residents to work longer than the current 80 hours per week limit.

Administrators say they are trying to be mindful of overtime for shift workers like doctors and nurses. “We do everything we can not to mandate overtime,” says Susan Ehrlich, CEO of SFGH. “We only do it in the most extreme of circumstances.”

At Sutter hospitals, Dr. Swisher says they are actively thinking about how to reduce contact with COVID-19 patients.

“Clearly limiting exposure is important,” he says. “We try to do that by limiting peoples’ actual presence and rotating people out and make sure they can rest.”

But, he adds, they haven’t figured out exactly how to do that yet.