Prevalence of SARS-CoV-2 antibodies during phased access to vaccination: results from a population-based survey in New York City, September 2020-March 2021.

Repeated serosurveys are an important tool for understanding trends in severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection and vaccination. During 1 September 2020-20 March 2021, the NYC Health Department conducted a population-based SARS-CoV-2 antibody prevalence survey of 2096 NYC adults who either provided a blood specimen or self-reported the results of a previous antibody test. The serosurvey, the second in a series of surveys conducted by the NYC Health Department, aimed to estimate SARS-CoV-2 antibody prevalence across the city and for different groups at higher risk for adverse health outcomes. Weighted citywide prevalence was 23.5% overall (95% confidence interval (CI) 20.1-27.4) and increased from 19.2% (95% CI 14.7-24.6) before coronavirus disease 2019 vaccines were available to 31.3% (95% CI 24.5-39.0) during the early phases of vaccine roll-out. We found no differences in antibody prevalence by age, race/ethnicity, borough, education, marital status, sex, health insurance coverage, self-reported general health or neighbourhood poverty. These results show an overall increase in population-level seropositivity in NYC following the introduction of SARS-CoV-2 vaccines and highlight the importance of repeated serosurveys in understanding the pandemic's progression.

Prevalence of SARS-CoV-2 Antibodies in New York City Adults, June-October 2020: A Population-Based Survey.

BACKGROUND: Serosurveys help to ascertain burden of infection. Prior severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) serosurveys in New York City (NYC) used nonrandom samples. During June-October 2020, the NYC Health Department conducted a population-based survey estimating SARS-CoV-2 antibody prevalence in NYC adults. METHODS: Participants were recruited from the NYC 2020 Community Health Survey. We estimated citywide and stratified antibody prevalence using a hybrid design: serum tested with the DiaSorin LIAISON SARS-CoV-2 S1/S2 IgG assay and self-reported antibody test results were used together. We estimated univariate frequencies and 95% confidence intervals (CI), accounting for complex survey design. Two-sided P values ≤ .05 were statistically significant. RESULTS: There were 1074 respondents; 497 provided blood and 577 provided only a self-reported antibody test result. Weighted prevalence was 24.3% overall (95% CI, 20.7%-28.3%). Latino (30.7%; 95% CI, 24.1%-38.2%; P < .01) and black (30.7%; 95% CI, 21.9%-41.2%; P = .02) respondents had a higher weighted prevalence compared with white respondents (17.4%; 95% CI, 12.5%-23.7%). CONCLUSIONS: By October 2020, nearly 1 in 3 black and 1 in 3 Latino NYC adults had SARS-CoV-2 antibodies, highlighting unequal impacts of the coronavirus disease 2019 (COVID-19) pandemic on black and Latino NYC adults.