The global prevalence and association between the risk of myocarditis and mRNA-based COVID-19 vaccination: A network meta-analysis [version 1; peer review: awaiting peer review]

Background: Cases of myocarditis development have been reported after administration of messenger ribonucleic acid (mRNA)-based coronavirus disease (COVID-19) vaccines. However, the reports vary among the studies, and the types of mRNA vaccines with potential to cause myocarditis remain unidentified. The objective was to assess the cumulative prevalence of myocarditis and determine the association between myocarditis and mRNA-based COVID-19 vaccination. Methods: We performed a network meta-analysis by searching articles in PubMed, Scopus, and Web of Science. Information on the prevalence of myocarditis after the mRNA-based COVID-19 vaccination was collected from each study. Analysis was performed by calculating the pooled prevalence rate, and the association was determined using the Z-test. Data networking was performed using the Bayesian method. Results: A total of 18 papers was included in our analysis. We found that the cumulative prevalence of myocarditis was 1.7, 1.9, 1.2, and 1.1 per 100,000 population after vaccination with different types of mRNA-based COVID-19 vaccines, namely all mRNA COVID-19 vaccines, BNT162b1, mRNA-1273, and the combination of BNT162b1 and mRNA-1273, respectively. Moreover, the results revealed that BNT162b1 vaccination increased the risk of myocarditis by 1.64- and 1.71-folds compared to mRNA-1273 and the combination of BNT162b2 and mRNA-1273, respectively. Similar risks of developing myocarditis were observed after mRNA-1273 and the combination of BNT162b1 and mRNA-1273 vaccination. Conclusions: Our findings suggest the cumulative prevalence of myocarditis after mRNA-based COVID-19 vaccination with maximum prevalence was observed after BNT162b2 administration. BNT162b2 was associated with a higher risk of developing myocarditis than the other mRNA-based COVID-19 vaccines.