SARS-CoV-2 seroprevalence worldwide: a systematic review and meta-analysis

Rostami, A.; Sepidarkish, M.; Leeflang, M.; Riahi, S.M.; Shiadeh, M. Nourollahpour; Esfandyari, S.; Mokdad, A.H.; Hotez, P.J.; Gasser, R.B.

BACKGROUND: COVID-19 is arguably the most important public health concern in 2020 worldwide, and efforts are now escalating to suppress or eliminate its spread. OBJECTIVE: In this study, we undertook a meta-analysis to estimate the global and regional SARS-CoV-2 seroprevalence rates in humans, and to assess whether seroprevalence associates with geographical, climatic and socio-demographic factors. DATA SOURCES: We systematically reviewed PubMed, Scopus, Embase, medRxiv and bioRxiv databases for preprints or peer-reviewed articles (up to 14 August 2020). STUDY ELIGIBILITY CRITERIA: Population-based studies describing the prevalence of anti-SARS-CoV-2 (IgG and/or IgM) serum antibodies. PARTICIPANTS: People of different socio-economic and ethnic backgrounds – from the general population – whose prior COVID-19 status was unknown were tested for the presence of anti-SARS-CoV-2 serum antibodies. INTERVENTIONS: There were no interventions. METHODS: We used a random-effects model to estimate pooled seroprevalence, and then extrapolated the findings to the global population (for 2020). Subgroup and meta-regression analyses explored potential sources of heterogeneity in the data, and relationships between seroprevalence and socio-demographic, geographical and/or climatic factors. RESULTS: In total, 47 studies involving 399,265 people from 23 countries met the inclusion criteria. Heterogeneity (I(2) = 99.4%, P < 0.001) was seen among studies; the SARS-CoV-2 seroprevalence in the general population varied from 0.37% to 22.1%, with a pooled estimate of 3.38% (95% CI, 3.05%–3.72%; 15,879/399,265). On a regional level, seroprevalence varied from 1.45% (0.95–1.94%; South America) to 5.27% (3.97–6.57%; Northern Europe, although some variation appeared to relate to the serological assay used. The findings suggested an association of seroprevalence with income levels, human development indices, geographical latitudes and/or climate. Extrapolating to the 2020 world population, we estimated that 263.5 million individuals had been exposed or infected at the time of this study. CONCLUSION: This study showed that SARS-CoV-2 seroprevalence varied markedly among geographic regions, as might be expected early in a pandemic. Longitudinal surveys to continually monitor seroprevalence around the globe will be critical to support prevention and control efforts, and might indicate levels of endemic stability or instability in particular countries and regions. A. Rostami, Clin Microbiol Infect 2020.