Analysis of Cell Immunity for Children Infected with SARS-CoV-2 and Those Vaccinated against SARS-CoV-2 Using T-SPOT.COVID.

Cellular immunity is critical for the regulation of viral diseases, including coronavirus disease 2019 (COVID-19), and is generally considered immature in childhood. However, the details of cellular immunity against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection among children are unclear. We assessed cellular immunity in eight children post-vaccination against SARS-CoV-2 and 11 children after SARS-CoV-2 infection using the T-SPOT.COVID assay for the spike (S) and nucleocapsid (N) proteins. In the vaccinated group, the T-SPOT.COVID assay for the S protein yielded positive results in seven children. In the post-infection group, the assay for the N protein was positive for 5 of 11 children, with 3 of these 5 children requiring hospitalization, including 2 who needed mechanical ventilation. The T-SPOT.COVID assay is thus valuable for assessing cellular immunity against SARS-CoV-2, and most children infected with SARS-CoV-2 may not develop such immunity unless the disease severity is significant.