Charity Duplessis, 47, a nurse at Allegheny General, said she has had trouble sleeping and worries the stress will burn her out just as her career is starting. She got her nursing degree in May. “I hear call bells in my sleep,” she said.

Claire Zangerle, chief nurse executive at Allegheny Health Network, said 1,100 nurse positions are open at Allegheny General and 13 other hospitals, up from 300 at this time last year. Ms. Zangerle said she has been giving nurses more flexible schedules and lobbying state lawmakers to use Covid-19 relief funds to pay healthcare workers.

“I can tell you every single day, every hour of the day, I’m trying to figure out how to help my nurses,” she said.

More than 1,000 hospitals have been reporting daily critical staffing shortages in recent weeks, according to federal data. The healthcare sector has lost nearly 500,000 workers since February 2020, according to estimates from the Bureau of Labor Statistics.