The following are key points to remember from a viewpoint on myocarditis after the BNT162b2 messenger RNA (mRNA) severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) vaccine, reporting low incidence and mild severity:

1. The risks of acute myocarditis associated with SARS-CoV-2 mRNA vaccination, especially in male teenagers, have raised great concern and garnered intense media attention.
2. Myocarditis in general practice, independent of vaccination, is most common in young men and resolves spontaneously in at least half of patients, but may lead to dilated cardiomyopathy, heart transplantation, or death in up to a quarter of cases.
3. Historically, myocarditis has been reported as a rare adverse event after vaccinations, especially smallpox, influenza, and hepatitis B vaccinations and in the pre–coronavirus disease 2019 (COVID-19) era. Among 620,195 reports filed at the United States Vaccine Adverse Event Reporting System (VAERS) between 1990 and 2018, 0.1% were attributable to myopericarditis.
4. By July 2021, the Centers for Disease Control and Prevention (CDC) reported a likely association between the SARS-CoV-2 mRNA vaccines and cases of myocarditis and pericarditis; the reported CDC myocarditis/pericarditis rate was low, approximately 12.6 cases per million second-dose mRNA vaccine among individuals aged 12–39 years.
5. Almost all confirmed cases of acute myocarditis associated with COVID-19 vaccination with follow-up showed resolution of symptoms; and among those who had follow-up electrocardiogram/echocardiography and laboratory testing, most had returned to normal status.
6. By contrast, the incidence of COVID-19 infection-associated cardiac injury or myocarditis is estimated to be 100 times higher (1,000–1,400 per 100,000 people with COVID-19) than that of SARS-CoV-2 mRNA-vaccine-related myocarditis. Moreover, in contrast to the overall mild presentation and good outcome of vaccine-associated myocarditis, COVID-19 is associated with a higher risk of cardiovascular complications.
7. Two recent studies reported retrospective data on cases of presumed myocarditis that were detected after receipt of the BNT162b2 mRNA vaccine (Pfizer–BioNTech) in Israel. Witberg and colleagues identified 54 cases of myocarditis among >2.5 million vaccinated persons listed in the database of health care organizations with an overall estimated incidence of myocarditis up to 42 days after at least one dose of vaccine of 2.13 cases per 100,000 persons (95% confidence interval, 1.6–2.7).
8. Mevorach et al., reported 136 definite or probable cases of myocarditis during the surveillance of approximately 5.1 million persons receiving two doses of the BNT162b2 mRNA vaccine, with an incidence of 0.6 cases per 100,000 people within 21 days after the first dose and 3.8 cases per 100,000 people within 21 days after the second dose.
9. The mechanism of acute myocarditis associated with COVID-19 vaccination is not known but may be related to mRNA sequence that encodes for the spike protein of SARS-CoV-2, or to the immune response that follows vaccination. The propensity of young adults to develop myocarditis following the second dose of vaccine supports the hypothesis of the vaccine-associated maladaptive immune response, related to sex hormone differences, causing cardiac injury.
10. Available data suggest that the risk of acute myocarditis associated with COVID-19 vaccination is very low, although more common in young male patients. Furthermore, vaccine-related myocarditis is self-limiting in most cases. These data should reassure physicians, patients, the general population, and media, as the benefit–risk assessment for SARS-CoV-2 mRNA vaccination shows a highly favorable balance for vaccination across all age and sex groups.

Clinical Topics: Cardiac Surgery, Cardiovascular Care Team, Congenital Heart Disease and Pediatric Cardiology, COVID-19 Hub, Heart Failure and Cardiomyopathies, Invasive Cardiovascular Angiography and Intervention, Noninvasive Imaging, Pericardial Disease, Prevention, Cardiac Surgery and Arrhythmias, Cardiac Surgery and CHD and Pediatrics, Cardiac Surgery and Heart Failure, CHD and Pediatrics and Arrhythmias, CHD and Pediatrics and Imaging, CHD and Pediatrics and Interventions, CHD and Pediatrics and Prevention, CHD and Pediatrics and Quality Improvement, Acute Heart Failure, Heart Transplant, Interventions and Imaging, Echocardiography/Ultrasound

Keywords: Adolescent, Adverse Drug Reaction Reporting Systems, Cardiomyopathy, Dilated, COVID-19, COVID-19 Vaccines, Echocardiography, Electrocardiography, Heart Failure, Heart Transplantation, Immunity, Mass Vaccination, Myocarditis, Pericarditis, Primary Prevention, Risk Assessment, RNA, Messenger, SARS-CoV-2, Spike Glycoprotein, Coronavirus, Vaccination, Young Adult

< Back to Listings