A new preprint study analized data on myocarditis and pericarditis caused by the first dose of mRNA COVID-19 vaccine in the Jan 1, 2021 – Feb 11, 2022 period, collected from the EudraVigilance database and combined with the European Centre for Disease Prevention and Control’s (ECDC) vaccination tracker database.
It found that the Pfizer and Moderna vaccines produced a myocarditis standarized morbidity ratio (SMR) meaning, the number of cases compared with the background incidence, greater than 1, with the Moderna vaccine having a greater SMR than Pfizer’s.
The SMR for pericarditis after the Pfizer vaccine was greater than 1 when considering the lowest background incidence but smaller than 1 when considering the highest background incidence, meaning that there was not a clear relation between pericarditis and Pfizer vaccine administration. However, the Moderna vaccine produced a SMR >1 when compared with both, lowest and highest background incidence.
The authors conclude that the analysis supports an excess risk of myocarditis following the first dose of the mRNA COVID-19 vaccine, but the direction of the relationship between pericarditis and mRNA COVID-19 vaccine remains unclear, and that future research is needed to calculate age and sex standardized reporting rates, stratified OE analyses, as well as analyses following the second or more doses of mRNA COVID-19 vaccine.