Seven Bay Area counties on Monday jointly announced renewed indoor mask requirements, regardless of vaccination status, to limit spread of the highly contagious delta variant of COVID-19.
The public health offices of Alameda, Contra Costa, Marin, San Francisco, San Mateo, Santa Clara and Sonoma counties, along with the city of Berkeley, joined Sacramento, Los Angeles and Yolo counties in making masks mandatory in indoor public settings, with limited exceptions.
Those 10 counties combine for more than 19 million residents — about half of California’s total population of 39.5 million.
“We must act now to protect ourselves, our loved ones and our community. If you are eligible to get a COVID-19 vaccine and have not yet done so, please do not wait any longer,” Contra Costa County health officer Dr. Chris Farnitano said in a prepared statement.
The Bay Area orders take effect Tuesday. There is no set end date or condition, as health officials say they will monitor local conditions.
The changes in mask rules come in light of revised guidelines from the Centers for Disease Control and Prevention, which updated its recommendations last week.
The California Department of Public Health also updated its state-level guidance last week to recommend, but not require, universal indoor masking. The state dropped its statewide mandate for the fully vaccinated on June 15, in line with CDC guidance at the time.
Los Angeles, the nation’s most populous county at 10 million residents, returned to a mask mandate July 17. Sacramento and Yolo counties did so last week, shortly after the new federal recommendations.
Elsewhere in the Sacramento area, El Dorado and Placer counties had not as of Monday morning moved toward mask mandates, nor has the Yuba-Sutter bicounty region.
The CDC reversed course on masks due to evidence suggesting that some of the fully vaccinated who contract “breakthrough” infections of the delta variant, while rare, may maintain the ability to transmit the virus to others.
COVID-19 activity has been surging for several weeks in California, where health officials say delta made up more than 80% of sampled cases in July.
The federal agency’s guidelines recommend universal masking in areas with more than 50 weekly cases per 100,000 residents, or about 7.1 per day.
Forty-seven of California’s 58 counties making up a vast majority of the state’s population were above that threshold as of Monday, according to CDPH, including all counties in the greater Bay Area except Monterey.
Alameda, Contra Costa, Los Angeles, Sacramento, San Francisco, Sonoma and Yolo counties — as well as California as a whole — are all at more than double the threshold.