Figure 6.

Cross-sectional and longitudinal analysis of S1-specific memory T cell responses in COVID-19 patients

(A–C) Dynamics of S1-specific memory IL-2, IFN-γ, and IL-2/IFN-γ-producing T cells with the corresponding second order polynomial fitting curve (in black).

(D–F) T cells were measured in control (n = 11), COVID-19 samples at five study periods: 14–30 days (n = 11), 31–90 (n = 9), 91–180 days (n = 19), 181–365 (n = 28), and 366–452 (n = 6) days after symptom onset, as well as vaccine samples after first (n = 15) and second (n = 11) dose. For each time interval, the proportion of positive samples is indicated below the X axis.

(G–I) For longitudinal analysis, samples were taken at two (n = 10) or more (n = 5) time points and further comparisons were made between paired samples (n = 8) at two time points ranging from 6 to 15 months (TP1: 181–300 and TP2: 301–452 days after symptoms onset; right panel). The results were expressed as the number of spots per 300,000 seeded cells after subtracting the background spots of the negative control. The horizontal black lines indicate the median value and 95% CI of the group. The cutoff value (dashed red line) was set at the highest number of specific T cell spots for the negative controls (>7 to nine spots/300,000 seeded cells depending on the T cell population). The cutoff-value is not visible in some graphs because it is very close to the X axis. Mann-Whitney U test. ∗∗p ≤ 0.01, ∗∗∗p ≤ 0.001, and ∗∗∗∗p ≤ 0.0001. See also Figures S4, S5 and S6.