Seroprevalence of SARS-CoV-2-Specific IgG Antibodies Among Adults Living in Connecticut: Post-Infection Prevalence (PIP) Study

Mahajan, Shiwani; Srinivasan, Rajesh; Redlich, Carrie A.; Huston, Sara K.; Anastasio, Kelly M.; Cashman, Lisa; Massey, Dorothy S.; Dugan, Andrew; Witters, Dan; Marlar, Jenny; Li, Shu-Xia; Lin, Zhenqiu; Hodge, Domonique; Chattopadhyay, Manas; Adams, Mark D.; Lee, Charles; Rao, Lokinendi V.; Stewart, Chris; Kuppusamy, Karthik; Ko, Albert I.; Krumholz, Harlan M.

BACKGROUND: A seroprevalence study can estimate the percentage of people with SARS-CoV-2 antibodies in the general population, however, most existing reports have used a convenience sample, which may bias their estimates. METHODS: We sought a representative sample of Connecticut residents, aged ≥18 years and residing in non-congregate settings, who completed a survey between June 4 and June 23, 2020 and underwent serology testing for SARS-CoV-2-specific IgG antibodies between June 10 and July 29, 2020. We also oversampled non-Hispanic Black and Hispanic subpopulations. We estimated the seroprevalence of SARS-CoV-2-specific IgG antibodies and the prevalence of symptomatic illness and self-reported adherence to risk mitigation behaviors among this population. RESULTS: Of the 567 respondents (mean age 50 [±17] years; 53% women; 75% non-Hispanic White individuals) included at the state-level, 23 respondents tested positive for SARS-CoV-2-specific antibodies, resulting in weighted seroprevalence of 4.0 (90% confidence interval [CI] 2.0–6.0). The weighted seroprevalence for the oversampled non-Hispanic Black and Hispanic populations was 6.4% (90% CI 0.9–11.9) and 19.9% (90% CI 13.2–26.6), respectively. The majority of respondents at the state-level reported following risk mitigation behaviors: 73% avoided public places, 75% avoided gatherings of families or friends, and 97% wore a facemask, at least part of the time. CONCLUSIONS: These estimates indicate that the vast majority of people in Connecticut lack antibodies against SARS-CoV-2 and there is variation by race/ethnicity. There is a need for continued adherence to risk mitigation behaviors among Connecticut residents to prevent resurgence of COVID-19 in this region.