Where every Bay Area county stands on metrics to lift COVID-19 indoor mask mandates

All eight Bay Area counties still enforcing an indoor mask mandate are using the same shared metrics that will determine when the mandates will be lifted, and some counties are closer to hitting those metrics than others.

The criteria are as follows:

1. A county reaches the "moderate" (yellow) tier of case rates as determined by the Centers for Disease Control and Prevention's data tracker and remains there for three weeks.

2. The county health officer determines that COVID-19 hospitalizations are "low and stable."

3. 80% of a county's total population is fully vaccinated against COVID-19 or eight weeks have passed since a COVID-19 vaccine has been authorized for children ages 5-11.

Currently, four Bay Area counties — Marin, San Mateo, Alameda and San Francisco — are in the yellow tier. Marin was the first to enter the yellow tier a week and a half ago, and was followed shortly after by San Mateo County. Alameda County was added to the yellow tier last week, and San Francisco joined on Monday.

Of those four counties, only Marin is at the 80% vaccination rate required to lift the mandate. County Health Officer Dr. Matt Willis has even assigned an earliest possible date for when the mask mandate can be lifted (Nov. 3), but noted that any case or hospitalization uptick will set that back.

To qualify for the yellow tier, a county must report fewer than 50 new COVID-19 cases per 100,000 residents over the past seven days. The CDC tracker lists Marin's seven-day case rate at 48.29, meaning any slight case uptick could dislodge the county from the yellow tier and reset the three-week clock that the counties decided upon.

Alameda and San Francisco counties are also teetering with case rates of 48.17 and 46.4, respectively. San Mateo County is a little bit safer with a case rate of 44.35. Those three counties all have total population vaccination rates above 70%, and should hit the 80% threshold once authorization is given for children ages 5-11 to begin receiving doses, a development that could come as soon as this week.

Of course, if it takes weeks for children to become fully vaccinated (doses are given two weeks apart), a county teetering on the case requirement could fall out of the yellow tier while waiting to fulfill vaccination requirement, then have to re-enter the yellow tier and maintain for another three weeks, ensuring mask mandates linger.

Of the four Bay Area counties not in the yellow tier — Contra Costa, Santa Clara, Napa and Sonoma — Santa Clara is the closest one to entering with a seven-day case rate of 53.17. Contra Costa, Napa and Sonoma are further away with case rates of 67.97, 65.34 and 57.86, respectively. All three counties have seen weeks of sustained case decreases and have total population vaccination rates close to 70%, and, as a result, may not hit the 80% benchmark as quickly as other Bay Area counties will once the vaccine is approved for children ages 5-11.

Contra Costa County Health Officer Dr. Chris Farnitano had previously told his board of supervisors that in a best-case scenario, the county will meet metrics by late December or early January.

Solano County has no indoor mask mandate and is not using any of the criteria.