LAUSR

Abstract Purpose New York State (NYS) is an epicenter of the SARS-CoV-2 pandemic in the United States. Reliable estimates of cumulative incidence in the population are critical to tracking the extent of transmission and informing policies. Methods We conducted a statewide seroprevalence study among a 15,101 patron convenience sample at 99 grocery stores in 26 counties throughout NYS. SARS-CoV-2 cumulative incidence was estimated from antibody reactivity by first post-stratification weighting then adjusting by antibody test characteristics. The percent diagnosed was estimated by dividing diagnoses by estimated infection-experienced adults. Results Based on 1,887 of 15,101 reactive results (12.5%), estimated cumulative incidence through March 29 was 14.0% (95% CI: 13.3-14.7%), corresponding to 2,139,300 (95% CI: 2,035,800-2,242,800) infection-experienced adults. Cumulative incidence was highest in New York City (NYC) 22.7% (95% CI: 21.5-24.0%) and higher among Hispanic/Latino (29.2%), non-Hispanic black/African American (20.2%), and non-Hispanic Asian (12.4%) than non-Hispanic white adults (8.1%, p<.0001). An estimated 8.9% (95% CI: 8.4-9.3%) of infections in NYS were diagnosed, with diagnosis highest among adults ≥55 years (11.3%, 95% CI: 10.4-12.2%). Conclusions From the largest US serosurvey to date, we estimated > 2 million adult New York residents were infected through late March, with substantial disparities, although cumulative incidence remained below herd immunity thresholds. Monitoring, testing, and contact tracing remain essential public health strategies.