CXCR5+PD-1+++ cTfh cells expanded after seasonal influenza vaccination in our UK cohort, confirming their responsiveness to immunization (Fig. 7, A and B; Carr et al., 2016; Heit et al., 2017) and the presence of HA-specific T cells within this population was confirmed (Fig. S2, D and E). The gene discussed is CXCR5; the disease is influenza.