Assessing the Value of T cell Monitoring in the General Population of Children and Adolescents - Insights From the Ciao Corona Cohort Study

Objectives: Serological monitoring of SARS-CoV-2 antibodies in children and adolescents has been crucial for pandemic surveillance and response, while the role of T cell response monitoring remains uncertain. This study aimed to assess the potential of T cell response monitoring in children and adolescents during the COVID-19 pandemic. Methods: We compared antibody and T cell-mediated immune responses in a subpopulation (n = 109) of children and adolescents from the Ciao Corona cohort study. Participants were followed up over 6 months, from November/December 2021 to June/July 2022, during the Delta and Omicron waves in Switzerland. Results: Circulating, virus-specific T cell responses in children and adolescents were generally low and heterogeneous. T cell-mediated responses were not consistent with SARS-CoV-2 infection status, with responses detectable in some seronegative individuals and not detectable in a considerable number of seropositive participants. Conclusion: Circulating, virus-specific T cell responses to SARS-CoV-2 in children and adolescents from the general population offer limited additional insight. Monitoring humoral immunity is likely a more cost-effective approach and should be the primary focus of immunological surveillance in the general paediatric population.