Research Alert
Newswise — The kinetics and durability of T cell and antibody responses to SARS-CoV-2 in children have not been well-characterized. We leveraged a longitudinal convalescent cohort of children (N = 30) aged 6 months to 20 years with PCR-confirmed (28/30) or serology-confirmed (2/30) COVID-19 in whom peripheral blood mononuclear cells (PBMC) and sera were archived at approximately 1 month, 6 months, and 12 months post-symptom onset. Nucleocapsid-specific (N) T cell functionality was evaluated utilizing intracellular flow cytometric analysis and combinatorial polyfunctionality analysis of antigen-specific T-cell subsets (COMPASS). CD4+ T cell responses to N declined over time with low cytokine production in children less than 5 years. These data suggest that cell-mediated immunity to natural SARS-CoV-2 infection in children wanes quickly, with the greatest decreases seen in children less than 5 years of age. Conversely, spike-specific (S) CD4+ T cell functionality scores remained stable up to one year after initial infection, and included signals from Th1 cytokines (IFN-γ, IL-2, TNF-α). Consistent with this, anti-S neutralizing antibody titers increased over the course of the study in children greater than 5 years, likely as a result of vaccination. Because children experience more mild disease compared to adults but can carry similar viral loads, our data suggest children may be susceptible to re-infection in the absence of vaccine-induced protection.
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