Alliance for Pandemic Preparedness

March 3, 2021

Estimation of Secondary Household Attack Rates for Emergent SARS-CoV-2 Variants Detected by Genomic Surveillance at a Community-Based Testing Site in San Francisco

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  • [Pre-print, not peer-reviewed] Some SARS-CoV-2 variants circulating in San Francisco with increasing prevalence may spread more efficiently to household contacts when compared to prior variants. Using SARS-CoV-2 genomic sequencing and epidemiological data collected from a walk-up rapid testing site in San Francisco, household contacts exposed to individuals infected with certain variants (including those with mutations L452R, S13I, and W152C) were more likely to be infected compared to household contacts exposed to lineages lacking these variants (RR=1.3; 95%CI: 1.01-1.64). These lineages of concern comprised 55% of the total sequences from January, compared to 16% in November. Viral loads were similar among persons infected with these variants versus other circulating strains, as was the proportion of individuals with symptoms (61% vs 64%). The authors suggest that the results indicate a modest transmissibility increase associated with these variants appearing on the West Coast.

Peng et al. (Mar 3, 2021). Estimation of Secondary Household Attack Rates for Emergent SARS-CoV-2 Variants Detected by Genomic Surveillance at a Community-Based Testing Site in San Francisco. Pre-print downloaded Mar 3 from https://doi.org/10.1101/2021.03.01.21252705