background: Viral transmission and disease dynamics of COVID-19 in sub-Saharan Africa are still not well understood. This study aims to provide further insight into the epidemiology of COVID-19 in Malawi by estimating the SARS-CoV-2 prevalence and immunity after SARS-CoV-2 infection in a hospital-based setting.
methods: We conducted a hospital-based, convenience sampling, cross-sectional survey for SARS-CoV-2 in Lilongwe, Malawi. Participants answered a questionnaire and were tested for SARS-CoV-2 infection using ELISA and RT-PCR. To estimate immunity, a surrogate virus neutralization test was performed in all seropositive samples. Poisson regression was performed to assess the association of SARS-CoV-2 point p... More
background: Viral transmission and disease dynamics of COVID-19 in sub-Saharan Africa are still not well understood. This study aims to provide further insight into the epidemiology of COVID-19 in Malawi by estimating the SARS-CoV-2 prevalence and immunity after SARS-CoV-2 infection in a hospital-based setting.
methods: We conducted a hospital-based, convenience sampling, cross-sectional survey for SARS-CoV-2 in Lilongwe, Malawi. Participants answered a questionnaire and were tested for SARS-CoV-2 infection using ELISA and RT-PCR. To estimate immunity, a surrogate virus neutralization test was performed in all seropositive samples. Poisson regression was performed to assess the association of SARS-CoV-2 point prevalence and demographic and behavioral variables.
results: A total of 930 participants were included in the study. We found a combined point prevalence of 10.1% (95% CI 8.4-12.3). Separately analyzed, the RT-PCR positivity was 2.0 % (95% CI 1.2-3.4), and the seropositivity was 9.3% (CI 95% 7.6-11.4). Of the tested seropositive samples, 90.1% (95% CI 81.2%-95.1%) were also tested positive in the surrogate virus neutralization assay. We found a high rate of asymptomatic SARS-CoV-2 infection (45.7%). SARS-CoV-2 point prevalence was significantly associated with being health care worker (PR 1.7; 95% CI 1.1-2.5).
conclusions: Our study suggests that official data underestimate the true magnitude of COVID-19 transmission. Performance of sVNT to estimate immunity in Malawi is feasible and revealed a considerable rate of post-infection immunity in our cohort. Subclinical infection and transmission are probably a game-changer with regards to surveillance, mitigation and vaccination strategies.
background: GIZ German Development and RKI Germany supported this study.
