High seroprevalence of SARS-CoV-2 in Burkina-Faso, Ghana and Madagascar in 2021: a population-based study

Abstract

Background The current COVID-19 pandemic affects the entire world population and has serious health, economic and social consequences. Assessing the prevalence of COVID-19 through population-based serological surveys is essential to monitor the progression of the epidemic, especially in African countries where the extent of SARS-CoV-2 spread remains unclear. Methods A two-stage cluster population-based SARS-CoV-2 seroprevalence survey was conducted in Bobo-Dioulasso and in Ouagadougou, Burkina Faso, Fianarantsoa, Madagascar and Kumasi, Ghana between February and June 2021. IgG seropositivity was determined in 2,163 households with a specificity improved SARS-CoV-2 Enzyme-linked Immunosorbent Assay. Population seroprevalence was evaluated using a Bayesian logistic regression model that accounted for test performance and age, sex and neighbourhood of the participants. Results Seroprevalence adjusted for test performance and population characteristics were 55.7% [95% Credible Interval (CrI) 49·0; 62·8] in Bobo-Dioulasso, 37·4% [95% CrI 31·3; 43·5] in Ouagadougou, 41·5% [95% CrI 36·5; 47·2] in Fianarantsoa, and 41·2% [95% CrI 34·5; 49·0] in Kumasi. Within the study population, less than 6% of participants performed a test for acute SARS-CoV-2 infection since the onset of the pandemic. Conclusions High exposure to SARS-CoV-2 was found in the surveyed regions albeit below the herd immunity threshold and with a low rate of previous testing for acute infections. Despite the high seroprevalence in our study population, the duration of protection from naturally acquired immunity remains unclear and new virus variants continue to emerge. This highlights the importance of vaccine deployment and continued preventive measures to protect the population at risk.

Explaining the unexpected COVID-19 trends and potential impact across Africa.

“…53,102 The prevailing social and environmental conditions across Africa likely mean that the spread of SARS-CoV-2 has been rather extensive. This is supported, for example, by the observation of up to 41 % average seroprevalence of SARS-CoV-2 antibodies in randomly sampled individuals across Ghana, 103,104 compared to official figures of approximately 0.54 % for cumulative total infection rate as of September 2022. 1 Similar situations have been reported in other African countries.…”

Knowledge of COVID-19 and the impact on indigents’ access to healthcare in Burkina Faso

“…Difficulties in enumeration and reporting constraints at both local and central level have also contributed to underestimating the number of cases and deaths in these countries. Thus, several large-scale seroprevalence studies have been conducted in this region, revealing a much more considerable spread of SARS-CoV-2 [ 28 ] than what official statistics would suggest. In Burkina Faso, a study conducted in 2021 reported a seroprevalence of 50.6% in Bobo-Dioulasso and 32.6% in Ouagadougou.…”

Morbidity and mortality burden of COVID-19 in rural Madagascar: results from a longitudinal cohort and nested seroprevalence study

“…Our results reveal that seroprevalence was lower in this rural district of Madagascar than in the nearby city of Fianarantsoa (about 1h30 drive from Ifanadiana), where seroprevalence in blood donors was already about 20% by November 2020 [15] and over 40% by February-June 2021 according to a cross-sectional household survey [53]. This is consistent with studies conducted in other African settings, which found that seroprevalence tends to be lower in rural populations than in their urban counterparts [13,54–60], with a few exceptions [61,62].…”

“…However, our study goes further, revealing the substantial heterogeneity in the spatio-temporal patterns of rural infections. Populations in the district living within 5km to roads or large towns had comparable or higher seroprevalence rates to those from urban Fianarantsoa [15,53], which highlights the major role played by population density and road connectivity in the spread of COVID-19 even in rural areas of the developing world where both factors are significantly lower than in urban settings.…”