FIGURE 1.

SARS‐CoV‐2‐specific T‐cell response identifies previously infected individuals. IFN‐γ (A) and IL‐2 (B) release in response to the SARS‐CoV‐2 S‐/NP‐/M‐combined peptide pool was measured in 102 evaluable, non‐vaccinated participants, subdivided into those with prior COVID‐19‐positive PCR test result (blue, n = 13–15), or those with no prior positive COVID‐19 test, termed ‘unknown/naïve’ (orange, n = 86–87). Statistical analyses indicate the results of a Kruskal–Wallis test (**** p < 0·0001). (C) The SARS‐CoV‐2‐specific IL‐2⁺ T‐cell response was correlated with the IFN‐γ⁺ response, subdivided by participant status. The anti‐SARS‐CoV‐2 RBD IgG antibody titre was correlated with the magnitude of IFN‐γ⁺ T‐cell response (D) and IL‐2⁺ T‐cell response (E); results of regression analyses are indicated. Sensitivity and specificity read‐outs for IFN‐γ (F) and IL‐2 (G) were defined by receiver operating characteristic curves (optimal cut‐off for IFN‐γ 22·7 pg/ml; IL‐2 23·31 pg/ml). The area under the curve (AUC) and associated P value are indicated