Alliance for Pandemic Preparedness

June 17, 2020

SARS-CoV-2 Community Transmission During Shelter-in-Place in San Francisco



  • [pre-print, not peer reviewed] All residents and non-residents who work in a densely-populated, majority Latinx San Francisco community were offered SARS-CoV-2 RT-PCR testing (2,598 of 5,174 residents and 1,355 non-resident workers were tested). The estimated SARS-CoV-2 prevalence among residents was 4% among Latinx vs 0.2% among non-Latinx, while estimated prevalence among workers was 10% for Latinx and 0% for non-Latinx workers. Twenty-nine percent of PCRpositive participants remained asymptomatic after two weeks of follow-up. The estimated seroprevalence of SARS-CoV-2 antibodies was 3% among residents and 8% among workers, and estimated cumulative incidence (antibody or PCR positive) was 6%Phylogenetic analysis detected representatives from five globally circulating clades, suggesting multiple independent introductions.  

Chamie et al. (June 17, 2020). SARS-CoV-2 Community Transmission During Shelter-in-Place in San Francisco. Pre-print downloaded June 17 from