Fading SARS-CoV-2 humoral and sustained cellular immunity in
convalescent children and adolescents
Abstract
Cross-reactive cellular and humoral immunity can substantially
contribute to antiviral defense against SARS-CoV-2 variants of concern
(VOC). While the adult SARS-CoV-2 cellular and humoral immunity and its
cross-recognition potential against VOC is broadly analyzed, similar
data regarding the pediatric population are missing. In this study, we
perform an analysis of the humoral and cellular SARS-CoV-2 response
immune of 32 convalescent COVID-19 children (children), 27 convalescent
vaccinated adults(C+V+) and 7 unvaccinated convalescent adults (C+V-).
SARS-CoV-2 reactive T cell response is analyzed via multiparametric
flowcytometry and humoral immunity is addressed via pseudovirus
neutralization assay. Similarly to adults, a significant loss of
neutralizing capacity against delta and omicron VOC was observed 6
months after SARS-CoV-2 infection. While SAR-CoV-2 neutralizing capacity
was comparable among children and C+V- against all VOC, children
demonstrated as expected an inferior humoral response when compared to
C+V+. Nevertheless, children generated SARS-CoV-2 reactive T cells with
broad cross-recognition potential. When compared to V+C+, children
presented even comparable frequencies of WT-reactive CD4+ and CD8+ T
cells with high avidity. Our results suggest that following SARS-CoV-2
infection children generate a humoral SARS-CoV-2 response with
neutralizing potential comparable to unvaccinated COVID-19 convalescent
adults as well a sustained SARS-CoV-2 cellular response cross-reactive
to VOC.