Seroprevalence of SARS-CoV-2 antibodies in the general population of
Bamako, Mali, and factors associated with infection: a population-based
cross-sectional study
Abstract
Background: The seroepidemiological characteristics of SARS-CoV-2
infection in Mali are not yet well understood. This study assessed
SARS-CoV-2 antibody seroprevalence and factors associated with infection
in the general population of Bamako, the capital city and epicenter of
COVID-19, to determine the magnitude of the pandemic and contribute to
control strategies improvement in Mali. Methods: A cross-sectional
survey was conducted in September 2022 to collect data on
sociodemographic information, clinical characteristics, comorbid
factors, and blood samples. ELISA was performed to determine anti-Spike
(S) and anti-RBD antibody levels, and RT-PCR to confirm SARS-CoV-2
infection in oropharyngeal swabs. A total of 3601 participants were
enrolled in RedCap. Result: the mean age of participants was 33.5±15.9
years old; the sex ratio female: male was 3.6:1. The most representative
were the 20–29 (28.9%, n=1043) and the 30–39 (26.9%, n=967)
years-old. The COVID-19 vaccine coverage among the participants was
35.8%, with vaccines from Covidshield AstraZeneca (AZ, 13.4%), Johnson
and Johnson (J&J, 16.7%), Sinovac (3.9%), and BioNTech Pfizer
(1.8%). Overall, S protein and RBD antibodies seroprevalence was
remarkably high in the general population (98% and 97%, respectively).
Factors such as youth (1–9 years old) and male sex were associated with
lower antibody responses against S and RBD, whereas previous exposure to
patients with COVID-19 and receiving the COVID-19 vaccine were
associated with increased odds of antibody responses. Conclusion: This
serosurvey demonstrated the high seroprevalence of SARS-CoV-2 antibodies
and highlighted the factors that may influence antibody responses,
clearly underlining an underestimation of the pandemic in Mali.