Lewis HC, Ware H, Whelan MG, Subissi L, Li Z, Ma X, Nardone A, Valenciano M, Cheng B, Noel KC, Cao C. SARS-CoV-2 infection in Africa: A systematic review and meta-analysis of standardised seroprevalence studies, from January 2020 to December 2021. medRxiv. 2022. doi: https://doi.org/10.1101/2022.02.14.22270934
The results and/or conclusions contained in the research do not necessarily reflect the views of all CITF members.
This systemic review, released in a preprint that has not yet been peer reviewed, estimated that seroprevalence in Africa (due to infection or vaccination) rose from 3% in Q2 2020 to 65.1% in Q3 2021. The review was conducted in partnership between SeroTracker (a CITF-funded initiative) and the World Health Organization UNITY initiative. When looking at the ratio of seroprevalence from infection to confirmed cases, there was a very wide spread across countries ranging from 10:1 to 958:1, meaning that many infections go by undetected.
- In this meta-analysis, seroprevalence from infection or vaccination across Africa rose from 3.0% as of mid-2020 to 65.1% as of mid-2021.
- The ratio of infections to reported cases varied widely, from 10:1 to 958:1, with the highest under-ascertainment found in Nigeria (958:1, July 2021) and Malawi (696:1, October 2020), and the lowest in Sierra Leone (57:1, March 2021) and South Africa (10:1, November 2020).
- Most studies sampled blood donors (45%, n=68) or the general population (by sampling random households or communities that agree to participate) (45%, n=68).
- The most common test used to measure seroprevalence was the Wantai SARS-CoV-2 Total Ab ELISA procured by WHO for standardization (27%, n=41), other Enzyme Linked Immunosorbent Assays (ELISA) (33%, n=50), or Chemiluminescent Assays (CLIA) (25%, n=37).
To determine the seroprevalence of SARS-CoV-2 in Africa, a systematic review and meta-analysis was conducted. A total of 54 full texts, comprising 151 unique studies published during the search dates of 1 January 2020 to 30 December 2021, were identified. This included published studies, pre-prints, and results from WHO UNITY study collaborators who had not yet made results available to the general public. From the total 151 studies identified, 41% (22/54) of the WHO African Continent Member States are represented, which make up 71% of the continent’s population.
This study provides timely information on seroprevalence in Africa. Case ascertainment ratios demonstrate large differences between reported cases and infections, highlighting the need for efficient surveillance systems as well as timely seroprevalence studies.