Severity of adverse reactions is associated with T-cell response in mRNA-1273 vaccinated health care workers.

Knowledge about mRNA-1273 elicited T-cell response is limited. We investigated adverse reactions and interferon gamma release by specific T-cells among mRNA-1273 vaccinated health care workers. Seven to 13 weeks after complete vaccination low levels of specific T-cells were detected not correlating with antibody response. Severity of symptoms after first and number of symptoms after second immunization were associated with T-cell response. Assessment of T-cell response in addition to antibody response is crucial because even few specific T-cells could add to protection against infection. Investigation of mRNA-1273 induced inflammatory processes might help improve reactogenicity and immunogenicity.