Interest of seroprevalence surveys for the epidemiological surveillance of the SARS‐CoV‐2 pandemic in African populations: Insights from the ARIACOV project in Benin

Abstract

Background Many SARS‐CoV‐2 seroprevalence surveys since the end of 2020 have disqualified the first misconception that Africa had been spared by the pandemic. Through the analysis of three SARS‐CoV‐2 seroprevalence surveys carried out in Benin as part of the ARIACOV project, we argue that the integration of epidemiological serosurveillance of the SARS‐CoV‐2 infection in the national surveillance packages would be of great use to refine the understanding of the COVID‐19 pandemic in Africa. Methods We carried out three repeated cross‐sectional surveys in Benin: two in Cotonou, the economic capital in March and May 2021, and one in Natitingou, a semi‐rural city in the north of the country in August 2021. Total and weighted‐by‐age‐group seroprevalences were estimated and the risk factors for SARS‐CoV‐2 infection were assessed by multivariate logistic regression. Results In Cotonou, a slight increase in overall age‐standardised SARS‐CoV‐2 seroprevalence from 29.77% (95% CI: 23.12%–37.41%) at the first survey to 34.86% (95% CI: 31.57%–38.30%) at the second survey was observed. In Natitingou, the globally adjusted seroprevalence was 33.34% (95% CI: 27.75%–39.44%). A trend of high risk for SARS‐CoV 2 seropositivity was observed in adults over 40 versus the young (less than 18 years old) during the first survey in Cotonou but no longer in the second survey. Conclusions Our results show that, however, rapid organisation of preventive measures aimed at breaking the chains of transmission, they were ultimately unable to prevent a wide spread of the virus in the population. Routine serological surveillance on strategic sentinel sites and/or populations could constitute a cost‐effective compromise to better anticipate the onset of new waves and define public health strategies.

SARS-CoV-2 seroprevalence among Beninese pregnant women in the third year of the pandemic

“…In Benin as of April 2024, 28,036 cases of COVID-19 had been reported [ 1 ]. None of the study participants had been diagnosed with COVID-19 during their pregnancy, and although there is no data on prior COVID-19 diagnosis, it is most likely that COVID-19 cases may have not been entirely captured by routine surveillance systems, as 76.4% of the unvaccinated study participants presented antibodies, which is also in accordance with the seroprevalence studies performed in the general population in Cotonou and Natitingou [ 2 ]. In the same line, a meta-analysis reporting on SARS-CoV-2 global seroprevalence has found that the ratio of seroprevalence to cumulative incidence of confirmed cases reported by the WHO ranged from 82.2:1 in July-September 2020 to 176.7:1 in July-September 2021 in the WHO African region, in comparison to global ratios ranging from 51.3:1 to 10.5:1.…”

“…The underreporting of COVID-19 cases in Benin has already been pointed by SARS-CoV-2 seroprevalence surveys performed at the community level in the country, which found that SARS-CoV-2 seroprevalence was over 30% from March to August 2021 [ 2 ]. In addition, our results, obtained one year afterwards, suggest that SARS-CoV-2 seroprevalence has raised greatly from mid-2021 to mid-2022.…”

“…For sample size calculation, we used the 30% SARS-CoV-2 seroprevalence estimate from the general population-based results from a study conducted in Benin in 2021 [ 2 ]. A sample size of at least 323 women was calculated to be needed to determine the prevalence of infection with a precision of 0.05 and a 95% confidence interval (95% CI).…”

“…However, the true extent of the pandemic may be much higher than officially reported. Serological surveys performed in Benin, in March and May 2021 in Cotonou and in August 2021 in Natitingou, found seroprevalences of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) of 29.8% (Cotonou, March), 34.9% (Cotonou, May) and 33.3% (Natitingou, August) [ 2 ].…”