IL2 and susceptibility to pneumonia measurement: Regarding the cytokine profile of S-specific T-cells, post-COVID-19 patients with pneumonia and vaccinated subjects produced similar levels of TH1 cytokines, in particular IFNγ, IL-2, TNFα, and MIP-1β, which were significantly higher than in post-COVID-19 patients with mild symptoms (Figure 3A–E).