Figure. Incidence of SARS-CoV-2 Infection in the Presence of Spike-Specific T Cells in Seronegative Children in England.

Infection in children confirmed by polymerase chain reaction test; spike-specific cellular responses determined by interferon-γ enzyme-linked immunospot assay. The proportion of the cohort testing positive was calculated as a proportion of the whole cohort at each time point. Children with a positive test in the surveillance period before the SARS-CoV-2 Omicron (BA.1) wave (December 1, 2021, to January 31, 2022) were excluded from analysis of infection during the Omicron wave. PBMC indicates peripheral blood mononuclear cell; SFC, spot-forming cell.