Characteristics of SARS‐CoV‐2 positive individuals in California from two periods during notable decline in incident infection

INTRODUCTION Between February and May 2021, the weekly case rate of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) declined in California from 270 to 32.9 cases per 100 000 individuals. 1 The cause of the dramatic decline is likely multifactorial but greatly influenced by population-level immunity due to prior infection and increasing vaccination coverage (see Figure 1). Data extrapolated from U.S. COVID Risk & Vaccine Tracker2 SARS-CoV-2, however, continues to be transmitted heterogeneously among different subsets of the population. 3 The recent resurgence (from 17 to 173 cases per 100 000 individuals between June and August in California) 1 and fears that SARS-CoV-2 variants 4 may escape immunity warrant continued epidemic monitoring. METHODS We conducted a retrospective cohort study among individuals presenting for SARS-CoV-2 polymerase chain reaction (PCR) testing to one of 150 drive-through publicly accessible commercial sites in California at two periods: (a) February 23-March 3, 2021, and (b) between April 15 and 30 2021. SARS-CoV-2 positive SARS-CoV-2 positivity Positivity ratio Feb Apr Feb Apr Feb Apr Feb vs Apr Feb Apr Feb Apr Feb Apr Feb vs Apr Total 24 929 30 119 1907 907 7.6% 3.0% 2.5 27 978 31 763 772 672 2.8% 2.1% 1.3 Age