Official case counts suggest Africa has not seen the expected burden of COVID-19 as predicted by international health agencies, and the proportion of asymptomatic patients, disease severity, and mortality burden differ significantly in Africa from what has been observed elsewhere. Testing for SARS-CoV-2 was extremely limited early in the pandemic and likely led to under-reporting of cases leaving important gaps in our understanding of transmission and disease characteristics in the African context. SARS-CoV-2 antibody prevalence and serologic response data could help quantify the burden of COVID-19 disease in Africa to address this knowledge gap and guide future outbreak response, adapted to the local context. However, such data are widely lacking in Africa. We conducted a cross-sectional seroprevalence survey among 1,192 individuals seeking COVID-19 screening and testing in central Cameroon using the Innovita antibody-based rapid diagnostic. Overall immunoglobulin prevalence was 32%, IgM prevalence was 20%, and IgG prevalence was 24%. IgM positivity gradually increased, peaking around symptom day 20. IgG positivity was similar, gradually increasing over the first 10 days of symptoms, then increasing rapidly to 30 days and beyond. These findings highlight the importance of diagnostic testing and asymptomatic SARS-CoV-2 transmission in Cameroon, which likely resulted in artificially low case counts. Rapid antibody tests are a useful diagnostic modality for seroprevalence surveys and infection diagnosis starting 5-7 days after symptom onset. These results represent the first step towards better understanding the SARS-CoV-2 immunological response in African populations.

BackgroundInfection with SARS-CoV-2 can lead to a detectable serological immune response even though extent of its protection is still not yet well known. We report long duration and resurgence of SARS-CoV-2 in patients with COVID-19. MethodsWe included a cohort of 99 participants from our non-blinded non-randomized evaluation of COVID-19 tests in Cameroon. Demographic and clinical information was collected from participants including self-reported age, race, ethnicity, and gender. Qualitative data was described as proportions while quantitative data was described with means and accompanying ranges.ResultsDuration of PCR for SARS-CoV-2 positivity was found to range from 4 – 81 days, with mean duration of 32.8 days in patients with PCR-positive. We also identified 4 participants who also had SARS-CoV-2 resurgence within a three-month period. ConclusionThese observations raise questions on clinical decision to release COVID-19 cases from isolation after 14 days.