Vaccine-Induced Specific Cellular and Humoral Immunity after MRNA-Based COVID-19 Vaccination in Athletes and Controls.

PURPOSE High-performance sports training has been associated with immunomodulatory activity on vaccine-induced immunity in athletes. To date, it is unknown, whether training in athletes may affect immunogenicity of mRNA-based vaccines, as the vaccine antigen is produced in the muscle. METHODS In an observational study, 57 athletes and 57 controls were recruited before and 2 weeks after the second vaccination with a COVID-19 mRNA vaccine. Spike-specific IgG-antibodies were quantified using ELISA. Quantitative and functional characterization of SARS-CoV-2-specific T-cells was carried out from whole blood using flow-cytometry. Adverse events within the first seven days after the first and the second vaccination were self-reported using a diary. RESULTS Levels of anti-spike IgG antibodies were similar in athletes (5766 (IQR 4923) BAU/ml) and controls (6677 (IQR 6741) BAU/ml, p = 0.317), which also held true for neutralizing activity (p = 0.185). In contrast, athletes reached significantly lower levels of spike-specific CD4 (p = 0.0001) and CD8 T-cells (p = 0.025). While most individuals from both groups had spike-specific CD4 T-cell levels above detection limit, the percentage of individuals with detectable CD8 T-cells was significantly lower among athletes (23/57 (40.4%)) as compared to controls (35/57 (61.4%), p = 0.039). Cytokine-expression profiling showed no major differences between the groups, whereas the expression of CTLA-4 was significantly lower in spike-specific CD4 T-cells of athletes. Overall, adverse events were similar among the groups except for more athletes reporting swelling at the injection site and headache. CONCLUSIONS COVID-19 mRNA vaccination was well tolerated and induced a strong humoral and cellular immune-response in both athletes and controls. The significantly lower levels of vaccine-specific T-cells with less CD8 T-cell responders among athletes may indicate mRNA vaccine-specific alterations in immune-responses related to high-performance sports training. Key Words: ANTIBODIES, IMMUNOGENICITY, SARS-COV-2, T CELLS, VACCINATION.