Recent reports demonstrate that some level of protective immunity can be acquired in humans against distinct heterosubtypic influenza infections (McMichael et al., 1983; Sridhar et al., 2013), and animal studies show that this protection can be mediated by memory CD8+ T cells targeting conserved antigens such as the IAV nucleoprotein (NP; Yewdell et al., 1985; Slütter et al., 2013). This evidence concerns the gene CD8A and influenza.