BackgroundStudies reporting estimates of the seroprevalence of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) antibodies have rapidly emerged. We aimed to synthesize seroprevalence data to better estimate the burden of SARS-CoV-2 infection, identify high-risk groups, and inform public health decision making.MethodsIn this systematic review and meta-analysis, we searched publication databases, preprint servers, and grey literature sources for seroepidemiological study reports, from January 1, 2020 to August 28, 2020. We included studies that reported a sample size, study date, location, and seroprevalence estimate. Estimates were corrected for imperfect test accuracy with Bayesian measurement error models. We conducted meta-analysis to identify demographic differences in the prevalence of SARS-CoV-2 antibodies, and meta-regression to identify study-level factors associated with seroprevalence. We compared region-specific seroprevalence data to confirmed cumulative incidence. PROSPERO: CRD42020183634.FindingsWe identified 338 seroprevalence studies including 2.3 million participants in 50 countries. Seroprevalence was low in the general population (median 3.2%, IQR 1.0-6.4%) and slightly higher in at-risk populations (median 5.4%, IQR 1.5-18.4%). Median seroprevalence varied by WHO Global Burden of Disease region (p < 0.01), from 1.0% in Southeast Asia, East Asia and Oceania to 18.8% in South Asia. National studies had lower seroprevalence estimates than local (p = 0.02) studies. Compared to White persons, Black persons (prevalence ratio [RR] 2.34, 95% CI 1.60-3.43) and Asian persons (RR 1.56, 95% CI 1.22-2.01) were more likely to be seropositive. Seroprevalence was higher among people ages 18-64 compared to 65 and over (RR 1.26, 95% CI 1.04-1.52). Health care workers had a 1.74x (95% CI: 1.18-2.58) higher risk compared to the general population. There was no difference in seroprevalence between sexes. There were 123 studies (36%) at low or moderate risk of bias. Seroprevalence estimates from national studies were median 11.9 (IQR 8.0 - 16.6) times higher than the corresponding SARS-CoV-2 cumulative incidence.InterpretationMost of the population remains susceptible to SARS-CoV-2 infection. Public health measures must be improved to protect disproportionately affected groups, including non-White people and adults. Measures taken in SE Asia, E Asia and Oceania, and Latin America and Caribbean may have been more effective in controlling virus transmission than measures taken in other regions.FundingPublic Health Agency of Canada through the COVID-19 Immunity Task Force.