SARS-CoV-2 infections in children and young people

Felsenstein, Susanna; Hedrich, Christian M.

Though recent reports link SARS-CoV-2 infections with hyper-inflammatory states in children, most children experience no/mild symptoms, and hospitalization and mortality rates are low in the age group. As symptoms are usually mild and seroconversion occurs at low frequencies, it remains unclear whether children significantly contribute to community transmission. Several hypotheses try to explain age-related differences in disease presentation and severity. Possible reasons for milder presentations in children as compared to adults include frequent contact to seasonal coronaviruses, presence of cross-reactive antibodies, and/or co-clearance with other viruses. Increased expression of ACE2 in young people may facilitate virus infection, while limiting inflammation and reducing the risk of severe disease. Further potential factors include recent vaccinations and a more diverse memory T cell repertoire. This manuscript reviews age-related host factors that may protect children from COVID-19 and complications associated, and addresses the confusion around seropositivity and immunity.