IFNG and influenza: In a study in Uganda, pre‐existing IFN‐γ producing NK cells in an activated immune microenvironment were associated with lower viral loads and subsequently reduced antibody titres after YF‐17D vaccination.38 NK cell IFN‐γ responses to YFV correlated with increased in vitro responsiveness of less differentiated NK cells to innate cytokines such as IL‐12 after vaccination30 suggesting that, as for influenza vaccines, YF‐17D‐induced accessory cell‐derived cytokines may also induce development of CIML NK cells.