First “snap-shot” meta-analysis to estimate the prevalence of serum antibodies to SARS-CoV-2 in humans

Background COVID-19 is arguably the number-one public health concern worldwide, and efforts are now escalating to control its spread. Objective In this study, we undertake a meta-analysis to estimate the global and regional anti-SARS-CoV-2 seroprevalence rates in humans and assess whether seroprevalence associates with geographical, climatic and socio-demographic factors. Data sources We systematically reviewed PubMed, Scopus, Embase, medRxiv and bioRxiv for peer-reviewed articles or preprints (up to 14 August 2020). Study eligibility criteria Population-based studies describing prevalence of anti-SARS-CoV-2 serum antibodies in general people. Participants general people who were tested for prevalence of anti-SARS-CoV-2 serum antibodies. Interventions There were no interventions. Methods We used random-effects model to estimate pooled seroprevalence, and then extrapolated these findings to the global population (for 2020). Sub-group and meta-regression analyses explored potential sources of heterogeneity in the data and relationships between seroprevalence and socio-demographic, geographical and climatic factors. Results In total, 47 serological studies involving 399,265 people from 23 countries met the inclusion criteria. The pooled seroprevalence of SARS-CoV-2 in general people was estimated at 3.38% (95% CI, 3.05%–3.72%; 15,879/399,265). On a regional basis, we determined seroprevalence estimates of 5.27% (3.97–6.57%) in Northern Europe; 4.41% (2.20–6.61%) in Southern Europe; 4.41% (3.03– 5.79%) in North America; 3.17% (1.96–4.38%) in Western Europe; 2.02% (1.56–2.49%) in the Eastern Asia; and 1.45% (0.95–1.94%) in South America. Extrapolating to the 2020 world population, we estimated that 263,565,606 individuals had been exposed or infected with SARS-CoV-2 at the first wave of the pandemic. A significantly higher seroprevalence was related to higher income levels and human development indices, higher geographical latitudes and lower mean environmental temperatures. Interpretation This study reinforces that SARS-CoV-2 infection is a very rapidly-spreading communicable disease and calls for routine surveys to constantly monitor temporal changes in seroprevalence around the globe.