Incidence of Severe Acute Respiratory Syndrome Coronavirus 2 Neutralizing Antibodies in a Rural Community in Western Kenya during the First 24 Months of the Coronavirus Disease 2019 Pandemic.

Seroreactivity to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) antigens was commonly reported in African settings during the early stages of the coronavirus disease 2019 pandemic. Severe acute respiratory syndrome coronavirus 2 neutralizing antibodies (nAbs) are not only correlated with functional protection from disease but also are highly specific responses to the virus. These responses were used to investigate the evolution of virus exposure in a community-based, longitudinal cohort of 504 individuals in rural Western Kenya. Eluates from dried blood spots collected every 3 months from January 2020 to September 2021 were tested for nAbs using a commercial kit. Only 10 individuals developed SARS-CoV-2 nAbs, all of which were clustered in December 2020 (wildtype virus) and September 2021 (delta variant). After seroconversion, all patients seroreverted within 2 months. Despite reports of widespread viral exposure in Western Kenya from 2020 to 2021, the paucity of nAbs highlights the limited natural immunity present when vaccines became available in late 2021 in Kenya.