COVID-19 mRNA Vaccination, ABO Blood Type and the Severity of Self-Reported Reactogenicity in a Large Healthcare System: A Brief Report of a Cross-Sectional Study.

Introduction It has been anecdotally observed that ABO blood type may have an impact on the severity of the side-effects experienced by those receiving mRNA vaccination for COVID-19.  Methods As part of a larger study, a retrospective cross-sectional survey was made available to approximately 33,000 front-line healthcare workers, students and volunteers who were offered voluntary vaccination in a state-wide healthcare system during phase one of the state's vaccine roll-out. A secondary endpoint of the survey was to determine if there was any relationship between vaccination reactogenicity and ABO blood type.  Results 4009 responses were received - a 12.15% response rate. 3700 respondents answered the blood type question, and of those, 2878 knew their blood type. By Kruskal-Wallis test, there was no statistically significant association between any blood type and any side effect for either of the COVID-19 mRNA vaccines.  Conclusions COVID-19 mRNA vaccination may cause significant reactogenicity. However, ABO blood type does not appear to be a predictor of vaccine reactogenicity.