Thus, IFN-γ-producing CD8+ T cells in R1, CD4+ T cells in R2 and NK cells in R3 ‘survival’ groups were markedly (and significantly) increased when compared with patients who died following H7N9 infection, suggesting that different immune responses at different times might be associated with recovery when compared with patients who died from H7N9 disease. This evidence concerns the gene IFNG and infection.