Until now, San Francisco, Marin, Sonoma and Alameda counties had allowed people to take their masks off in offices, gyms and religious gathering spaces like churches, provided everyone was fully vaccinated.
The counties had negotiated with the state to preserve those exemptions after California’s reinstatement of a universal mask mandate earlier this month.
But with data clearly showing that omicron is infecting vaccinated people in significant numbers, the exemptions are now gone. The counties’ new orders take effect at 12:01 a.m. on Thursday.
“When we see numbers like this, it’s time to respond,” said Dr. Matt Willis, Marin County public health officer.
Contra Costa County made a similar move to revoke mask exemptions on Tuesday. All nine Bay Area counties now are fully aligned with California’s indoor mandate.
Fully vaccinated people are at greater risk of infection than ever before in the pandemic. In California, case counts for fully vaccinated people stood at 13.6 cases per 100,000 and 70.5 cases per 100,000 unvaccinated for the week ending Dec. 19. Just one month earlier, the weekly average figures were 5.4 per 100,000 for vaccinated and 38.4 per 100,000 for unvaccinated.
And the latest rates are before omicron slipped into Christmas gatherings and sent infection rates even higher. In Sonoma County, holiday gatherings are the cause of 40% of new cases where the source of infection is known, according to county health officer Dr. Sundari Mase.
San Francisco reported its highest single-day case total ever on Tuesday — 805, according to state data and Chronicle analysis, which tends to differ slightly from the city’s official figures.
Actual numbers are certain to be higher because many people are taking home antigen tests and not reporting the results.
Hospitals are not overwhelmed yet, according to Contra Costa County Director of Public Health Dr. Ori Tzvieli, but they are getting more calls.
“What I’m concerned about is two to three weeks down the road when even more people have COVID,” he said.
Dr. Karen Relucio, the Napa County health officer, said hospitalizations remain stable and manageable so far.
“We have good capacity. We’re not at the highest level we’ve seen before,” she said.
Dr. Caesar Djavaherian, co-founder of the San Francisco-based care provider Carbon Health, said his company’s clinics typically see 40 to 50 patients a day but are now seeing roughly double that — and most of it is COVID.
“Clinics are getting overrun,” he said. “The wave is real.”
Asked about the mood among health care providers in the Bay Area, he said, “It’s 100% exhaustion.” Not only are care providers coping with potential exposures or infections in their own families, but on top of that they are seeing a flood of patients.
Health workers are trained to prioritize patients, but it “wears you down as a provider,” Djavaherian said, adding, “The degree of stress out there, especially for health care workers, is incredibly high.”
Experts urged people to take as many precautions as possible — get vaccinated, boosted, wear masks, gather only in small groups and do rapid tests beforehand — though a testing shortage obviously makes that difficult, and the tests are also not foolproof in terms of accurately detecting positive cases.
“At this point with omicron surging the way that it is, I would not recommend New Year’s celebrations unless they are small,” said Dr. Sara Cody, the Santa Clara County health officer. “Small, intimate gatherings are the way to gather this New Year. It’s not the time to go to a large gathering.”
Mase, of Sonoma County, went further. She recommended that those who are not vaccinated avoid holiday gatherings and travel. For those, vaccinated and unvaccinated, who choose to gather, she recommended well-fitting masks for everyone — and not cloth masks.
Dr. Bob Wachter, chair of the department of medicine at UCSF, said in a Twitter thread Wednesday that while things are hard now, significant improvements could be around the corner.
“By early February, we could be in a place where COVID is, in fact, ‘like the flu’ – with the vast majority of the U.S. protected through vaccines or recent infections, folks at higher risk having ready access to an oral treatment that markedly lowers their risk,” he wrote — though he added that this was by no means a certainty.
Chronicle staff writers Erin Allday and Nami Sumida contributed to this report.
Kate Galbraith is a San Francisco Chronicle staff writer. Email: kgalbraith@sfchronicle.com Twitter: @kategalbraith