Global reports of myocarditis following COVID-19 vaccination: A systematic review and meta-analysis

Background and aims: Recent media reports of myocarditis after receiving COVID-19 vaccines, particularly the messenger RNA (mRNA) vaccines, are causing public concern. This review summarizes information from published case series and case reports, emphasizing patient and disease characteristics, investigation, and clinical outcomes, to provide a comprehensive picture of the condition. Methods: A systematic literature search of PubMed and Google scholar was conducted from inception to April 27, 2022. Individuals who develop myocarditis after receiving the COVID-19 vaccine, regardless of the type of vaccine and dose, were included in the study. Results: Sixty-two studies, including 218 cases, participated in the current systematic review. The median age was 29.2 years; 92.2% were male and 7.8% were female. 72.4% of patients received the Pfizer-BioNTech (BNT162b2) vaccine, 23.8% of patients received the Moderna COVID-19 Vaccine (mRNA-1273), and the rest of the 3.5% received other types of COVID-19 vaccine. Furthermore, most myocarditis cases (82.1%) occurred after the second vaccine dose, after a median time interval of 3.5 days. The most frequently reported symptoms were chest pain, myalgia/body aches and fever. Troponin levels were consistently elevated in 98.6% of patients. The admission ECG was abnormal in 88.5% of cases, and the left LVEF was lower than 50% in 21.5% of cases. Most patients (92.6%) resolved symptoms and recovered, and only three patients died. Conclusion: These findings may help public health policy to consider myocarditis in the context of the benefits of COVID-19 vaccination.