Taken together with the significant positive correlation between frailty and plasma IL-6 observed in the parent vaccine trial (Figs. 1  Fig. 5), these results suggest that ILT2+CD57+ Dim NK-cells, increased by frailty-related inflammation, support the induction of antibodies against A/H3N2 following high-dose seasonal influenza vaccination in older adults. Here, IL6 is linked to influenza.