ABSTRACT
Background: By the end of the third wave of the coronavirus disease 2019 (COVID-19) epidemic (May-October 2021), only 3130 of the 57 268 confirmed cases of coronavirus disease 2019 (COVID-19) in the Democratic Republic of the Congo (DRC) were reported in Kongo Central. This province, and especially its capital city, Matadi, has essential trade and exchanges with Kinshasa, the epicenter of the COVID-19 epidemic in DRC. Kinshasa accounted for 60.0% of all cases during the same period. The true burden of COVID-19 in Matadi is likely underestimated. In this study, we aimed to determine the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) seroprevalence and associated risk factors after the third wave in Matadi. Methods: We conducted a population-based cross-sectional study in October 2021. Consenting participants were interviewed and tested using an enzyme-linked immunosorbent assay commercial kit. We applied univariable and multivariable analysis to evaluate factors associated with seropositivity and adjusted the seroprevalence for the test kit performance. Results: We included 2210 participants from 489 households. Female participants represented 59.1%. The median age was 27 years (interquartile range, 16-45 years). The crude SARS-CoV-2 seroprevalence was 82.3%. Age was identified as the main risk factor as younger age decreased the seropositivity odds. Accounting for clustering at the household level increased the seroprevalence to 83.2%. The seroprevalence increased further to 88.1% (95% confidence interval, 86.2%-90.1%) after correcting for the laboratory test kit performance. Conclusions: The SARS-CoV-2 seroprevalence was very high, contrasting with reported cases. Evidence generated from this population-based survey remains relevant in guiding the local COVID-19 response, especially vaccination strategies.
ABSTRACT
Serologic surveys are important tools for estimating the true burden of COVID-19 in a given population. After the first wave of SARS-CoV-2 infections, a household-based survey conducted in Kinshasa, Democratic Republic of the Congo, estimated >292 infections going undiagnosed for every laboratory-confirmed case. To ascertain the cumulative population exposure in Kinshasa after the second wave of COVID-19, we conducted a prospective population-based cross-sectional study using a highly sensitive and specific ELISA kit. The survey included 2,560 consenting persons from 585 households; 55% were female and 45% male. The overall population-weighted, test kit-adjusted SARS-CoV-2 seroprevalence was 76.5% (95% CI 74.5%-78.5%). The seroprevalence was 4-fold higher than during the first wave, and positivity was associated with age, household average monthly income, and level of education. Evidence generated from this population-based survey can inform COVID-19 response, especially vaccination campaign strategies in the context of vaccine shortages and hesitancy.
Subject(s)
COVID-19 , Male , Female , Humans , COVID-19/epidemiology , SARS-CoV-2 , Seroepidemiologic Studies , Cross-Sectional Studies , Democratic Republic of the Congo/epidemiology , Prospective Studies , Antibodies, ViralABSTRACT
BACKGROUND: In October 2020, after the first wave of coronavirus disease 2019 (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 severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) immunoglobulin G (IgG) antibodies in the general population in Kinshasa. METHODS: We conducted a cross-sectional, household-based serosurvey between 22 October 2020 and 8 November 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%] 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; Pâ <â .05). It was also higher in participants who reported hospitalization than among those who did not (29.8% vs 16.0%, respectively; Pâ <â .05). However, differences were not significant in the multivariate model (Pâ =â .1). CONCLUSIONS: 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.