Despite not proliferating after vaccination, γδ T cells in elderly individuals receiving the inactivated vaccine did increase perforin production and, after in vitro restimulation, proliferated and produced IFNγ and IL‐4.84 Similarly, the γδ T‐cell response in the nasal mucosa was attenuated in cigarette smokers relative to non‐smokers,85 suggesting these cells may represent a correlate for why smokers respond less well to influenza vaccination. The gene discussed is IFNG; the disease is influenza.