Background: COVID-19 vaccines have greatly decreased both rate of morbidity and mortality of the COVID-19 infection, but studies have reported myocarditis in patients after vaccination especially with mRNA vaccines. The purpose of this study is to identify if there is a significant correlation between COVID-19 vaccines and myocarditis.
Methods: We systematically searched PubMed, Web of Science, Scopus, Ovid, Google Scholar and did grey search of other databases using the following keywords and terms: “Myocarditis (“Myocarditis”[Mesh]) OR “Chagas Cardiomyopathy”[Mesh]) AND “COVID-19 Vaccines”[Mesh].
Results: A total of 42 related articles were found out of 357 articles after excluding duplicates and irrelevant articles, 3 cohort were eligible for the meta-analysis. 26 were case reports, 12 were case series and one was a letter which were included in the systematic review. Case reports, series and the letter had 143 patients, 132were male, 105 had myocarditis, 13 had acute myocarditis, and 4 fulminant myocarditis. The mean age of patients who developed myocarditis was (26.4±10.7) years, most frequent vaccine was Pfizer-BioNTech (117), then 16 Moderna, 6 Pfizer and Moderna and 3 Johnson & Johnson. Mean time to symptoms appearance was 2.8 days mostly after the second dose of the vaccine. Mean hospitalization time was 11.41 (days). Most clinical presentations were cough, chest pain and fever. Laboratory tests revealed increased C-reactive protein, increased troponin with all cardiac markers in most patients. Cardiac magnetic resonance imaging (MRI) revealed late gadolinium enhancement with myocardial edema and cardiomegaly. Also, electrocardiograms revealed ST-segment elevation in most patients. In the three cohort studies included in the meta-analysis, 546 patients had myocarditis out of 130158303 of the vaccinated group and 24 patients developed myocarditis out of 884828 of the non-vaccinated control group. We found statistically significant association between decreased incidence of myocarditis and receiving COVID-19 vaccines compared with the control group (RR= 0.15, 95% CI = 0.10 to 0.23, p value <0.00001).The incidence of myocarditis was 4.19 per 1 million of the people who received the vaccines.
Conclusions: No significant association was found between COVID-19 vaccines and incidence of myocarditis. The cause may result from immunologic or systemic association with COVID-19 vaccines which needs further studies to understand this pathogenesis.