Similarly, the proportion of infection-elicited TNFα+, IL2+ and polyfunctional CD4+ T-cells was significantly higher among influenza A/H3N2-infected (p = 0.038, 0.017 and 0.041 respectively) and influenza B-infected patients (p = 0.002, 0.048 and 0.004 respectively) than in vaccine recipients (Fig. 3 and Supplementary Fig. S4 online). Here, IL2 is linked to infection.