Myocarditis and pericarditis are rare adverse reactions, more commonly seen in young males after receiving the second dose of an mRNA vaccine. However, the benefits of vaccination heavily outweigh the risk of these side effects. In addition, vaccination boosters are effective against the newest, more infective variants. Therefore we expect more vaccines to be administered in the following years. The objective of this study is to review the current understanding of the mechanism, diagnosis, and treatment of myocarditis and pericarditis. Proposed mechanisms include molecular mimicry against the S protein and hypersensitivity reactions with mRNA vaccines and platelet aggregation and thrombus formation in cardiac blood vessels with adenoviral vaccines. Diagnosis of myocarditis is based on clinical findings, cardiac enzymes, ECG, MRI, and echocardiographic findings. Management includes NSAIDs and cardiovascular support in selected cases with ventricular dysfunction. Most patients have a mild presentation with preservation of cardiac function and recover entirely within seven days; the average hospital stay is three days. Long-term complications are infrequent.
Keywords: COVID-19; COVID-19 vaccines; Molecular mimicry; Myocarditis.
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