BACKGROUND: On October, 2020, after the first wave of COVID-19, only 8290 confirmed cases were reported in Kinshasa, Democratic Republic of the Congo, but the real prevalence remains unknown. To guide public health policies, we aimed to describe the prevalence of SARS-CoV-2 IgG antibodies in the general population in Kinshasa.
METHODS: We conducted a cross-sectional, household-based serosurvey between October 22, 2020, and November 8, 2020. Participants were interviewed at home and tested for antibodies against SARS-CoV-2 spike and nucleocapsid proteins in a Luminex based assay. A positive serology was defined as a sample that reacted with both SARS-CoV-2 proteins (100% sensitivity, 99.7% specificity). The overall weighted, age-standardized prevalence was estimated and the infection-to-case ratio was calculated to determine the proportion of undiagnosed SARS-CoV-2 infections.
RESULTS: A total of 1233 participants from 292 households were included (mean age, 32.4 years; 764 [61.2%] were women). The overall weighted, age-standardized SARS-CoV-2 seroprevalence was 16.6% (95% CI 14.0-19.5). The estimated infection-to-case ratio was 292:1. Prevalence was higher among participants ≥ 40 years than among those ˂18 years (21.2% vs 14.9%, respectively; p˂0.05). It was also higher in participants who reported hospitalization than among those who did not (29.8% vs 16.0%, respectively; p˂0.05). However, differences were not significant in the multivariate model (p=0.1).
CONCLUSION: The prevalence of SARS-CoV-2 is much higher than the number of COVID-19 cases reported. These results justify the organization of a sequential series of serosurveys by public health authorities to adapt response measures to the dynamics of the pandemic.