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.