Figure 2: SARS-CoV-2 specific CD4+ and CD8+ T cell responses increase over time and age.

Correlation of IFNγ responses for CD4⁺ (A) and CD8⁺ (B) T cells against the structural peptide pool with children (red) (n=34) and adults (black) (n=36) (with background IFNγ production to DMSO subtracted), against days post symptom onset. Black dotted lines represent the limit of detection (IFNγ of CD4⁺=0.000167 (A), IFNγ of CD8⁺=0.00011(B)). Fold change of IFNγ CD4⁺ (C) and CD8⁺ (D) T cell responses were calculated as the later time point (mean±stdev: 32.8±35.7 days, range: 9–138) over admission time point responses (mean±stdev: 7.6±4.2, range: 2–15)) in response to the structural, accessory and ORF1ab peptide pools in children and adults from two independent experiments (children n=14, adults n=14). One sample Wilcoxon tests were used for determining significance of fold changes, were *p<0.05. Acute (samples <14 days post symptom onset, mean±stdev: 8.0±3.8, range: 1–14, n=22 children, n=14 adults) (E-G), and convalescent/memory (H-J) (mean±stdev: 70.5±41.9, range: 15–180 days post symptom onset, n=12 children, n=22 adults) IFNγ structural specific (F, I) CD4⁺ and (G, J) CD8⁺ T cell responses and negative controls (n=10). For statistical comparisons between children and adults, or adults and negatives, Mann-Whitney tests were performed, *p<0.05, **p<0.01, ***p<0.001, ****p<0.0001. The magnitude of the acute (from E) and memory (from H) structural IFNγ CD4⁺ (F, I) and CD8⁺ (G, J) T cell response with age. R values are calculated using Spearman’s correlation and *p<0.05, **p<0.01, ***p<0.001, ****p<0.0001. Blue lines of linear regression represent the overall trend, and blue dotted lines show the upper and lower 95% confidence intervals. All data points are individual responses minus paired background IFNγ response to a DMSO control.