Lin, Pin-HungPin-HungLinHsiao, Po-JuPo-JuHsiaoPan, Ching-FuChing-FuPanLiu, Ming-TsanMing-TsanLiuJANN-TAY WANGChing, ChiChiChingWu, Fang-YiFang-YiWuLin, Yi-HsuanYi-HsuanLinYang, Yu-ChanYu-ChanYangHsu, Le-YinLe-YinHsuHUNG-CHIH YANGUN-IN WU2023-12-112023-12-112023-09-1500142980https://scholars.lib.ntu.edu.tw/handle/123456789/637661Repeated annual influenza vaccinations have been associated with reduced vaccine-induced antibody responses. This prospective study aimed to explore the role of vaccine antigen-specific regulatory T (Treg) cells in antibody response to repeated annual influenza vaccination. We analyzed pre- and postvaccination hemagglutination inhibition (HI) titers, seroconversion rates, seroprotection rates, vaccine antigen hemagglutinin (HA)-specific Treg cells, and conventional T (Tconv) cells. We compared these parameters between vaccinees with or without vaccine-induced seroconversion. Our multivariate logistic regression revealed that prior vaccination was significantly associated with a decreased likelihood of achieving seroconversion for both H1N1(adjusted OR, 0.03; 95% CI, 0.01-0.13) and H3N2 (adjusted OR, 0.09; 95% CI, 0.03-0.30). Furthermore, individuals who received repeated vaccinations had significantly higher levels of pre-existing HA-specific Treg cells than those who did not. We also found that vaccine-induced fold-increases in HI titers and seroconversion were negatively correlated with pre-existing HA-specific Treg cells and positively correlated with the ratio of Tconv to Treg cells. Overall, our findings suggest that repeated annual influenza vaccination is associated with a lower vaccine-induced antibody response and a higher frequency of vaccine-specific Treg cells. However, a lower frequency of pre-existing Treg cells correlates with a higher postvaccination antibody response.enInfluenza; Regulatory T cells; Repeated vaccination; Seroconversion; Seroprotection[SDGs]SDG3Association of vaccine-specific regulatory T cells with reduced antibody response to repeated influenza vaccinationjournal article10.1002/eji.202350525377137272-s2.0-85173544294https://api.elsevier.com/content/abstract/scopus_id/85173544294