Seroepidemiology of the Seasonal Human Coronaviruses NL63, 229E, OC43 and HKU1 in France

Background The seasonal human coronaviruses (HCoV) NL63, 229E, OC43, and HKU1 are globally endemic, yet the majority of HCoV infections remain undiagnosed. Methods In a cross-sectional study, 2389 serum samples were collected from children and adults in France in 2020. In a longitudinal cohort study, 2520 samples were collected from 898 French individuals followed up between 2020 and 2021. Antibodies to HCoVs were measured using a bead-based multiplex assay. Results The rate of waning of anti-HCoV spike immunoglobulin G antibodies was estimated as 0.22–0.47 year−1 for children, and 0.13–0.27 year−1 for adults. Seroreversion was estimated as 0.31–1.37 year−1 in children and 0.19–0.72 year−1 in adults. The estimated seroconversion rate in children was consistent with 20%–39% of children being infected every year with each HCoV. Conclusions The high force of infection in children indicates that HCoVs may be responsible for a substantial proportion of fever episodes experienced by children.