Measurement of binding antibodies to SARS-CoV-2 variants elicited by natural infection and COVID-19 vaccines in a sub-Saharan African population
Data on immune responses to COVID-19 vaccination in West and Central Africa remain limited, particularly across SARS-CoV-2 variants and vaccine platforms. Using the InVITE cohort in the Democratic Republic of Congo, Guinea, Liberia, and Mali, we evaluated anti-spike (anti-S) antibody binding to nine SARS-CoV-2 variants in 96 participants equally selected from pre-vaccination assay defined seropositive and seronegative groups. Participants received mRNA, adenovirus-vectored, or inactivated virus vaccines. Anti-S binding was measured before vaccination and two months after completion of the primary series using a Meso Scale Discovery 10-plex assay. Before vaccination, antibody binding was significantly higher against pre-Omicron variants (Ancestral, Alpha, Beta, and Delta) than Omicron variants in both seronegative (fold change [FC] 3.85, 99% CI 3.45–4.17) and seropositive (FC 3.57, 99% CI 3.33–3.84) participants. Seropositive individuals showed greater binding than seronegative individuals across all variants. Two months post-vaccination, mRNA vaccines elicited higher antibody binding than adenovirus-vectored or inactivated vaccines, whereas no significant differences were observed between adenovirus-vectored and inactivated vaccines. Antibody binding remained higher against pre-Omicron than Omicron variants across all vaccine platforms and serostatus groups. These findings provide rare data on variant-specific vaccine-elicited antibody binding responses in West and Central African populations with distinct demographic, epidemiologic, and immunologic background. Trial registration: Registration ClinicalTrials.gov: NCT05096091, Registration date: 10-26-2021, Clinical trial registry: https://clinicaltrials.gov/study/NCT05096091?term=NCT05096091rank=1#study-overview .