233 staffers at 2 San Francisco hospitals tested positive for coronavirus in July

At two major San Francisco hospitals, at least 233 staff members — most of them fully vaccinated — tested positive for the coronavirus in July, and most, according to a hospital official, involved the highly contagious delta variant.

Some of the cases were asymptomatic, most involved mild to moderate symptoms and only two required hospitalization, officials said. The infections were determined to be delta-related because most samples in San Francisco were tested for the variant, which is now dominant in the city.

About 75% to 80% of the more than 50 infected staff members at Zuckerberg San Francisco General Hospital were fully vaccinated, Dr. Lukejohn Day, the hospital’s chief medical officer, said in an interview Saturday. The University of California, San Francisco Medical Center said in a statement issued Friday that 153 of its 183 infected staff members had been fully vaccinated.

The statement from the UCSF Medical Center said two of the infected staff members required hospitalization. None of the infected staff members at San Francisco General have been hospitalized and most had mild to moderate symptoms, Day said. The asymptomatic cases were discovered through contact tracing.

Without vaccinations, Day said, the hospitalization rate would be much worse.

“We’re concerned right now that we’re on the rise of a surge here in San Francisco and the Bay Area,” Day said. “But what we’re seeing is very much what the data from the vaccines showed us: You can still get COVID, potentially. But if you do get it, it’s not severe at all.”

On July 11, San Francisco ordered that workers in high-risk workplaces, including hospitals, be vaccinated by Sept. 15. The UCSF statement said the hospital was “doubling down on our efforts to protect our staff. This includes requiring all employees and trainees to comply with the new UC-systemwide COVID-19 vaccination mandate, with limited exceptions for medical or religious exemptions.”

Staff members at both hospitals have continued to wear personal protective equipment, Day said. But the number of infected staffers reported in July is about as many as during the peak of the winter surge.

“We’re nervous that we could potentially exceed it,” Day said.