For participants with Omicron BA.5 single infection, though no significant difference were found for virus-specific cytokine secreting memory T cell responses among examined time points, the memory T cell responses were slightly higher at T3 than those at T2 and T4 except for the total or IFN-γ+IL-2- T cell responses against the WT peptides (Figure 2A). This evidence concerns the gene IL2 and infection.