Prevalence of SARS-CoV-2 antibodies in the Republic of Congo in mid-2021.

Objectives: To estimate the seroprevalence of severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) antibodies in the general population in the Republic of Congo. Methods: In this cross-sectional study, conducted from June to July 2021, participants were recruited from the general population in three districts in the Republic of Congo. Eligible participants were tested for anti-SARS-CoV-2 antibodies using a rapid diagnostic assay. Results: Overall, 31.8% [95% confidence interval (CI) 29.5-34.0] of the 1669 participants tested positive for anti-SARS-CoV-2 antibodies. Higher prevalence was observed in the rural region (37.3%, 95% CI 31.0-44.1%) than the urban region (30.9%, 95% CI 28.5-33.3); however, the difference was not significant. The risk of testing positive for anti-SARS-CoV-2 antibodies increased significantly with age, ranging from 22.5% (95% CI 18.1-27.5) in 15-24 year olds to 47.9% (95% CI 39.3-56.5) in 55-64 year olds. Conclusions: The antibody levels observed in this survey correlate with a moderate rate of virus circulation, which correlates with the low number of confirmed cases of coronavirus disease 2019 in the Republic of Congo.

Trend of expansion of SARS-CoV-2 infection and COVID-19 burden in Gabon (Central Africa) in mid-2021, based on a serological survey.

Objective: To estimate the seroprevalence of anti-SARS-CoV-2 antibodies in the general population in Gabon, Central Africa. Methods: From May to July 2021, a cross-sectional study involving participants recruited in the general population in three districts in Gabon was conducted. Eligible participants who provided written informed consent were tested for anti-SARS-CoV-2 antibodies using a simple rapid diagnostic assay. Results: Overall, 1609 participants were recruited, 1361 (84.6%) from urban sites and 248 (15.4%) from a rural area. The estimated overall seroprevalence was 13.1% (95% CI 11.4-14.8%). The risk of seropositivity increased with age, and the prevalence in the different age groups ranged from 12.9% (8.0-19.4%) in those aged 15-24 years to 23.3% (14.2-34.6%) in those ≥ 65 years old. A higher prevalence was found in the rural population (17.3%; 12.8-22.6%) compared with urban regions (12.3%; 10.6-14.1%). Being a woman was also associated with higher risk of infection (p < 0.001). Conclusions: This seroprevalence survey revealed a moderate seroprevalence in Gabon, illustrating a relatively low rate of circulation of the virus in the country and correlating with low numbers of confirmed cases and deaths reported to date.