SAN FRANCISCO, Aug. 3 (Xinhua) -- Starting from Tuesday, U.S. San Francisco Bay Area residents are once again required to wear masks for all in public indoor settings, regardless of vaccination status, to help stem transmission of the highly contagious Delta variant of the coronavirus.
Health officers for seven of the nine counties in the region -- Alameda, Contra Costa, Marin, San Francisco, San Mateo, Santa Clara, Sonoma, and the city of Berkeley announced the restriction on Monday.
The order affects more than 7 million residents in the region. Solano and Napa counties did not join in the new mask mandate.
"Indoor masking is a temporary measure that will help us deal with the Delta variant, which is causing a sharp increase in cases and we know increases in hospitalizations and deaths will follow," said Naveena Bobba, San Francisco's acting health officer.
The Bay Area has been averaging more than 1,400 cases a day over the past several days, surpassing the peak of last year's summer surge in mid-August, according to a report by the San Francisco Chronicle on Tuesday.
Regional hospitalizations have not yet reached last summer's peak but are not far off -- 815 people were in the hospital with COVID-19 on July 28 last year, compared with 713 on Sunday, the report said.
COVID-19 deaths in the Bay Area at about five a day, are well below last summer's peak of 20 a day.
Health officials emphasized that vaccination remains the best measure against the spread of COVID-19, but that masks are a strong tool while many people are unvaccinated.