Estimated Community Seroprevalence of SARS-CoV-2 Antibodies — Two Georgia Counties, April 28–May 3, 2020

Biggs, Holly M.; Harris, Jennifer B.; Breakwell, Lucy; Dahlgren, F. Scott; Abedi, Glen R.; Szablewski, Christine M.; Drobeniuc, Jan; Bustamante, Nirma D.; Almendares, Olivia; Schnall, Amy H.; Gilani, Zunera; Smith, Tiffany; Gieraltowski, Laura; Johnson, Jeffrey A.; Bajema, Kristina L.; McDavid, Kelsey; Schafer, Ilana J.; Sullivan, Vickie; Punkova, Lili; Tejada-Strop, Alexandra; Amiling, Raiza; Mattison, Claire P.; Cortese, Margaret M.; Ford, S. Elizabeth; Paxton, Lynn A.; Drenzek, Cherie; Tate, Jacqueline E.; Brown, Nicole; Chang, Karen T.; Deputy, Nicholas P.; Desamu-Thorpe, Rodel; Gorishek, Chase; Hanchey, Arianna; Melgar, Michael; Monroe, Benjamin P.; Nielsen, Carrie F.; Pellegrini, Gerald J.; Shamout, Mays; Tison, Laura I.; Vagi, Sara; Zacks, Rachael

Transmission of SARS-CoV-2, the virus that causes coronavirus disease 2019 (COVID-19), is ongoing in many communities throughout the United States. Although case-based and syndromic surveillance are critical for monitoring the pandemic, these systems rely on persons obtaining testing or reporting a COVID-19-like illness. Using serologic tests to detect the presence of SARS-CoV-2 antibodies is an adjunctive strategy that estimates the prevalence of past infection in a population. During April 28-May 3, 2020, coinciding with the end of a statewide shelter-in-place order, CDC and the Georgia Department of Public Health conducted a serologic survey in DeKalb and Fulton counties in metropolitan Atlanta to estimate SARS-CoV-2 seroprevalence in the population. A two-stage cluster sampling design was used to randomly select 30 census blocks in each county, with a target of seven participating households per census block. Weighted estimates were calculated to account for the probability of selection and adjusted for age group, sex, and race/ethnicity. A total of 394 households and 696 persons participated and had a serology result; 19 (2.7%) of 696 persons had SARS-CoV-2 antibodies detected. The estimated weighted seroprevalence across these two metropolitan Atlanta counties was 2.5% (95% confidence interval [CI] = 1.4-4.5). Non-Hispanic black participants more commonly had SARS-CoV-2 antibodies than did participants of other racial/ethnic groups (p<0.01). Among persons with SARS-CoV-2 antibodies, 13 (weighted % = 49.9; 95% CI = 24.4-75.5) reported a COVID-19-compatible illness,* six (weighted % = 28.2; 95% CI = 11.9-53.3) sought medical care for a COVID-19-compatible illness, and five (weighted % = 15.7; 95% CI = 5.1-39.4) had been tested for SARS-CoV-2 infection, demonstrating that many of these infections would not have been identified through case-based or syndromic surveillance. The relatively low seroprevalence estimate in this report indicates that most persons in the catchment area had not been infected with SARS-CoV-2 at the time of the survey. Continued preventive measures, including social distancing, consistent and correct use of face coverings, and hand hygiene, remain critical in controlling community spread of SARS-CoV-2.