An Oil-in-Water adjuvant significantly increased influenza A/H7N9 split virus Vaccine-Induced circulating follicular helper T (cTFH) cells and antibody responses

cT activation is associated with HAI and Neut responses in recipients of MF59-adjuvanted influenza A/H7N9 vaccine relative to unadjuvanted vaccine. Future studies should focus on optimizing the cT response and use cT as an early biomarker of serological response to vaccination. This trial was registered at clinicaltrials.gov, trial number NCT01938742.