Bay Area health officers Thursday laid out a list of conditions they say must be met before their regionwide requirement for everyone to wear face masks in indoor public places can end.

Those conditions are reaching the U.S. Centers for Disease Control & Prevention’s yellow “moderate” tier for COVID-19 transmission for at least three weeks, having low and stable hospitalization rates and either having 80% of the total population fully vaccinated or the shots authorized for kids age 5-11 for eight weeks.

The big question looming now is when will Bay Area counties meet the requirements to shed indoor masks? The answer is not for awhile and it appears fairly complicated.

The affected jurisdictions are Santa Clara, Alameda, Contra Costa, San Francisco, San Mateo, Marin, Napa, Sonoma counties and the City of Berkeley. Solano County didn’t join the other eight Bay Area counties in requiring masks indoors for everyone.

Most of those Bay Area health departments issued the masking requirements for their respective jurisdictions on Aug. 3, following a sharp rise in cases, hospitalizations, and deaths over the summer from the highly infectious delta variant.

With that case surge now receding, and with the Bay Area having some of the highest vaccination rates in the country, the health officers here said it’s time to plan for lifting the mask order.

“Masks and vaccines together have protected residents of Alameda County and the Bay Area during the summer wave” said Alameda County Health Officer Dr. Nicholas Moss. “While we expect COVID-19 and flu to circulate this winter, with more people well-protected from severe illness by vaccination we will be able to loosen mask requirements safely.”

But mask requirements won’t end for everyone. California’s health guidance for the use of face coverings may remain in effect after local masking requirements are lifted, meaning that people who are not fully vaccinated for COVID-19 must continue to wear masks in businesses and indoor public spaces.

The state also requires face coverings for everyone, regardless of vaccination status, in health care facilities, public transit and adult and senior care facilities. California’s masking guidelines in K-12 schools would also not be affected by changes to local health orders.

So how do Bay Area counties stack up under Thursday’s new mask metric?

  • Transmission: The CDC has four color-coded transmission tiers based on the total number of new cases per 100,000 people and percentage of positive tests for COVID-19 in the last seven days. The red high tier is for 100 or more cases and 10% or more positive, the orange substantial tier is for 50-99 cases and 8-9% positive, the yellow moderate tier is 10-49 cases and 5-75 positive and the blue low tier is below 10 cases and 5% positive. Among the nine Bay Area counties, Napa and Solano have high and the rest substantial transmission.
  • Hospitalization: The health officers did not provide a firm metric, saying only that it’s “in the judgment of the health officer.”
  • Vaccination: Though the Bay Area has high vaccination levels, they’re still short of 80% of their total populations fully vaccinated. The total population of fully vaccinated for local counties Thursday according to the CDC was 77% in Marin, 74% in Santa Clara and San Francisco, 72% in San Mateo, 70% in Alameda and Contra Costa and 67% in Sonoma and Napa.
    Alternatively, federal health authorities are scheduled to consider an application from Pfizer-BioNTech to grant emergency use of its COVID-19 vaccine for 5- to 11-year-olds on Oct. 26. If recommended by that committee and a similar one for the CDC, those agencies could authorize the vaccines for young children later this fall and the Bay Area mask orders could lift eight weeks after that.

Santa Clara County Health Officer Dr. Sara Cody said Thursday that the mask orders will likely lift county by county rather than all at once.

“It may be that one county reaches the metric before another adjacent county,” Cody said. “So we’ll probably be lifting masking requirement at different times, because hospitalization and transmission rates differ by county as well as vaccination rates.”

So when is that likely to happen?

“I think it’s going to be hard to say,” Cody said. “We have to meet all three metrics.”

County residents can easily track their county progress on transmission and vaccination, which the CDC reports on a dashboard, and counties plan to add total population vaccination rates to their own websites, Cody said. The hospitalization metric is a judgment call by the health officer and isn’t easily tracked, she said, but will be based on capacity.

“In Santa Clara County, our hospital capacity is robust, so that metric will be simple to meet,” Cody said. “The metric that’s most important and most challenging is the vaccination metric.”

Lifting a local indoor mask mandate would not prevent businesses, nonprofits, churches or others with public indoor spaces from imposing their own requirements. As COVID-19 easily spreads through airborne droplets, face coverings remain highly powerful in preventing its spread.

The Bay Area counties’ approach differed from that of Santa Cruz County, which lifted its indoor mask mandate Sept. 28 based solely on reaching the CDC’s moderate COVID-19 transmission level, which is based on local case rates and the percentage of positive tests for the virus.

The same day Santa Cruz County lifted its mask requirement, the CDC bumped the county’s transmission level back up to the orange “substantial” level. But county officials said they would not reimpose the mask order.

Cody said “we do not have a shared metric across the region for re-imposing the indoor masking requirement.”

“Some of the things we’ll all be looking out for is the emergence of a new variant, how the vaccines do over time with new variants emerging and things like that,” Cody said.

Medical experts at the University of California-San Francisco said Wednesday before the health officers made their announcement that they favored additional metrics beyond the CDC transmission rates based on hospitalization and vaccination rates.

“As a safety measure, along with vaccination, face coverings have been key to our success in the Bay Area in reducing transmission and protecting public health,” said San Mateo County Health Officer Dr. Scott Morrow. “As we look toward lifting the mandate, it’s vital for everyone who has not gotten vaccinated to consider getting vaccinated right away.”

Staff Writers Julia Prodis Sulek and Harriet Rowan contributed to this report.