Prevalence of IgG and IgM to SARS-CoV-2 and other human coronaviruses in The Democratic Republic of Congo, Sierra Leone and Uganda: A Longitudinal Study

Abstract Objectives We assessed the prevalence of immunoglobulin G (IgG) and immunoglobulin M (IgM) against four endemic human coronaviruses (HCoVs) and two SARS-CoV-2 antigens, among vaccinated and unvaccinated staff at health care centres in Uganda, Sierra Leone, and the Democratic Republic of Congo (DRC). Methods Government health facility staff who had patient contact in Goma (DRC), Kambia District (Sierra Leone), and Masaka District (Uganda) were enrolled. Questionnaires and blood samples were collected at three timepoints over four months. Blood samples were analysed with the Luminex MAGPIX®. Results Among unvaccinated participants, the prevalence of IgG/IgM antibodies against SARS-CoV-2 RBD or N-protein at enrolment was 70% in Goma (138/196), 89% in Kambia (112/126) and 89% in Masaka (190/213). IgG responses against endemic HCoVs at baseline were not associated with SAR-CoV-2 sero-acquisition during follow-up. Among vaccinated participants, those who had evidence of SARS-CoV-2 IgG/IgM at baseline tended to have higher IgG responses to vaccination compared to those SARS-CoV-2 seronegative at baseline, controlling for the time of sample collection since vaccination. Conclusions The high levels of natural immunity and hybrid immunity should be incorporated into both vaccination policy and prediction models of the impact of subsequent waves of infection in these settings.