SARS-CoV-2 Seroprevalence Survey Among District Residents Presenting for Serologic Testing at Three Community Based Test Sites in Washington, DC, July to August, 2020

Sherman, A.; Reuben, J.; David, N. S.; Quasie-Woods, D. P.; Gunn, J. K. L.; Nielson, C. F.; Lloyd, P.; Yohannes, A.; Puckett, M.; Powell, J. A.; Leonard, S.; Iyengar, P.; Johnson-Clarke, F.; Tran, A.; McCarroll, M.; Raj, P.; Davies-Cole, J.; Smith, J.; Ellison, J. A.; Nesbitt, L.

Background The District of Columbia (DC), a major metropolitan area, continues to see community transmission of SARS CoV 2. While serologic testing does not indicate current SARS CoV 2 infection, it can indicate prior infection and help inform local policy and health guidance. The DC Department of Health (DC Health) conducted a community based survey to estimate DC SARS CoV 2 seroprevalence and identify seropositivity associated factors. Methods A mixed-methods cross-sectional serology survey was conducted among a convenience sample of DC residents during July 27 through August 21, 2020. Free serology testing was offered at three public test sites. Participants completed an electronic questionnaire on household and demographic characteristics, COVID like illness (CLI) since January 1, 2020, comorbidities, and SARS-CoV-2 exposures. Univariate and bivariate analyses were conducted to describe the sample population and assess factors associated with seropositivity. Results Among a sample of 671 participants, 51 individuals were seropositive, yielding an estimated seroprevalence of 7.6%. More than half (56.9%) of the seropositive participants reported no prior CLI; nearly half (47.1%) had no prior SARS-CoV-2 testing. Race/ethnicity, prior SARS-CoV-2 testing, prior CLI, employment status, and contact with confirmed COVID-19 cases were associated with seropositivity (P<0.05). Among those reporting prior CLI, loss of taste or smell, duration of CLI, fewer days between CLI and serology test, or prior viral test were associated with seropositivity (P[≤]0.006). Conclusions These findings indicate many seropositive individuals reported no symptoms consistent with CLI since January or any prior SARS-CoV-2 testing. This underscores the potential for cases to go undetected in the community and suggests wider-spread transmission than previously reported in DC.