Previous studies on cellular immune response after influenza immunisation include a wide range of immune markers representing different cell types and signalling pathways, for example, interferon (IFN)-γ and tumour necrosis factor (TNF), secreted by T helper (Th) 1; interleukin (IL)-4, IL-5, IL-9 IL-10 and IL-13, secreted by Th2-cells; IL-2 and IL-12, secreted by cytotoxic T lymphocytes (CTL); and granzyme B (GZMB), a marker of T-cell-mediated cytotoxicity [13,14,15,16]. This evidence concerns the gene GZMB and influenza.