San Francisco, and Most of Bay Area, Just a Few Weeks From Herd Immunity

Herd immunity is the unicorn we’re all chasing as a way out of pandemic life, but reaching that point is easier said than done. San Francisco, however, looks like it’s on track to get there faster than any other major metropolitan California city.

What constitutes herd immunity varies widely depending on contagion rates for specific viruses. Given the highly transmissible nature of COVID-19, and the increased transmission of strain mutations, we need about 75 percent to be on the safe side of this health crisis, according to UCSF Dr. George Rutherford, while some experts suggest the goal should be closer to 80 percent.

Nearly 80 percent of San Francisco residents aged 12 and older have received at least one dose of the vaccine and 68 percent have been fully vaccinated. For comparison, Los Angeles County reports that just 65 percent of its population has partially vaccinated and only 54 percent have completed the series. It should be noted that LA County is only reporting vaccination rates for people aged 16 and older.  

San Francisco may be the Bay Area’s urban center, but vaccination rates in neighboring counties matter a lot as they impact overall transmission rates and health outcomes. Thankfully, we’re seeing relatively high rates in all nine of the greater region counties, as shown in the table below:

*Santa Clara County notes an issue with the California Immunization Registry data system, which is contributing to underreported vaccination totals.

Aside from Solano County, which is falling behind the vaccination curve, San Francisco and most of the surrounding Bay Area should be at or very close to herd immunity in the next three weeks if health departments can keep up the current trajectory.