In a joint statement on Friday, Bay Area health officials in seven counties and the city of Berkeley urged residents to consider wearing masks in indoors regardless of their vaccination status to slow the spread of the highly transmissible Covid-19 delta variant.

While fully vaccinated people are generally well-protected from serious illness from Covid-19, including its delta variants, the recommendation for everyone to wear masks while in indoor public places such as grocery or retail stores, theaters, and family entertainment centers is intended as an “added layer of protection for unvaccinated residents,” read the statement from officials in Alameda, Contra Costa, Marin, San Francisco, San Mateo, Santa Clara, Sonoma and Berkeley. Health officials from Napa and Solano counties did not join the others in the mask recommendation.

The announcement comes as Covid-19 cases are rising locally, with San Francisco health officials projecting new daily cases to reach an average of at least 80 new cases per day. On Thursday, Los Angeles health officials announced masks will be required indoors starting Sunday for all people regardless of vaccination status. That is the only California county to bring back a mask mandate since the statewide tier system and mask mandate was dropped for vaccinated people on June 15.

Health officials are urging businesses to adopt universal masking requirements for customers in indoor areas to provide better protection, but the recommendation is not yet a mandated requirement. Workplaces are still required to adhere to Cal/OSHA requirements around masking while fully vaccinated employees are also encouraged to wear masks indoors if their employer has not confirmed the vaccination status of everyone present, health officials added.

Universal mask-wearing indoors is a way to ensure easy verification that all unvaccinated people in those settings are safer, health officials said, adding, “vaccines are safe, effective, free, and widely available to everyone 12 and older.” People are fully vaccinated two weeks after their second dose for the Pfizer and Moderna vaccines, or two weeks after a single dose of the Johnson & Johnson vaccine.

Delta variants of Covid-19 have become the dominant strain in California, comprising 43% of all sequenced specimens statewide last month and representing 58% of new infections across the country, according to the Centers for Disease Control.

“We are asking our residents to collectively come together again in this effort to stem the rising cases until we can assess how our hospital capacity will be