Elite athletes on regular training show more pronounced induction of vaccine-specific T-cells and antibodies after tetravalent influenza vaccination than controls

•Regular training in elite athletes does not adversely affect vaccination responses.•Influenza-specific T-cell responses are more pronounced in elite athletes.•Influenza-specific neutralizing antibodies are more pronounced in elite athletes.•Local side-effects after vaccination were mild and did not differ in both groups. Compliance of elite athletes with vaccination recommendations is low mainly based on concerns about side-effects and perceived poor vaccine efficacy due to continued physical training. We therefore employed seasonal influenza vaccination to investigate the effect of regular physical training on vaccine-induced cellular and humoral immunity in elite athletes and controls. Lymphocyte subpopulations and vaccine-specific T-cells were quantified and functionally characterized from 45 athletes and 25 controls before, and 1, 2 and 26 weeks after vaccination. Moreover, influenza-specific antibodies and their neutralizing function were quantified. Both groups showed a significant increase in vaccine-reactive CD4 T-cell levels which peaked one week after vaccination (p