CITF-funded SeroTracker carried out a living systematic review of 968 seroprevalence studies that included 9.3 million participants in 74 countries. Their findings, published in PLOS One, suggest that the general population median seroprevalence worldwide was low (4.5%), but found important differences when comparing infection rates from diagnostic testing.
In this systematic review and meta-analysis, researchers from SeroTracker, along with several CITF members, searched online data bases, as well as government websites and media outlets, for studies reporting seroprevalence from January 1st 2020 to December 31st 2020. The review included studies that reported a sample size, study date, location, and seroprevalence estimate. Statistical analysis was used to correct for differences in tests used to measure the presence of antibodies and for aggregating results among specific subpopulations. A ratio of seroprevalence to PCR confirmed infections was also calculated.
A total of 968 unique seroprevalence studies, from 605 publications, were found. These included 9.3 million participants from 74 countries. The majority of studies were carried out at a regional level (36%) with 12% at a national level, and most reported population wide estimates (61%) as opposed to specific populations. The median test corrected estimate for population wide seroprevalence was 4.5%. In high income countries the median corrected estimate for population wide seroprevalence was 4.1%, whereas in low-middle income countries the median seroprevalence ranges from 0.6% (Southeast Asia, East Asia and Oceania) to 19.5% (South Asia).
Regarding specific subpopulations, the review found a median corrected seroprevalence estimate of 3.6% among health care workers and care givers, 7.5% in essential non-healthcare workers, 41.7% in people living in slums, and 59.2% among people living in assisted living and long term care facilities.
The median ratio of serologically confirmed infections to PCR cases was 18.1 to 1. Meaning that for each person with a positive PCR, there are 18.1 with positive serology tests.
This literature review and meta-analysis is an extensive compilation of serology data, which provides essential information for public policy. Seroprevalence remained low during the time frame of the review, indicating the need to maintain public health measures until vaccination efforts have achieved heard immunity.
SeroTracker was initiated in early April 2020 to serve the COVID-19 Immunity Task Force’s need for global serological testing data. It is hosted at the University of Calgary’s Centre for Health Informatics but is a global collaboration of 20 researchers, data scientists, and economists from six universities in the UK, Canada, and the United States. Visit the interactive dashboard at https://serotracker.com/en/Explore.
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Bobrovitz N, Arora RK, Cao C, Boucher E, Liu M, Donnici C, Yanes-Lane M, Whelan M, Perlman-Arrow S, Chen J, Rahim H, Ilincic N, Segal M, Duarte N, Van Wyk J, Yan T, Atmaja A, Rocco S, Joseph A, Penny L, Clifton DA, Williamson T, Yansouni CP, Evans TG, Chevrier J, Papenburg J, Cheng MP. Global seroprevalence of SARS-CoV-2 antibodies: A systematic review and meta-analysis. PLOS ONE. 16(6): e0252617. doi: 10.1371/journal.pone.0252617.