Some days, early in the coronavirus pandemic, John Matland would break down in tears during his drive to work at Staten Island University Hospital in New York.

New York City was the epicenter of the pandemic, and the days of frontline hospital workers like Matland were filled with sick and dying patients. No one knew how deadly COVID-19 really was, or how many asymptomatic people were unknowingly contributing to its spread.

Matland, a longtime CAT scan technologist, had a single N95 mask he was forced to reuse. Still, he showed up every day, entering vent room after vent room of the sick …