Myocarditis, Pericarditis Rare in Young Men After COVID-19 Vaccination With Moderna Vaccine


While the vaccines continue to provide critical, evidence-based protection against the coronavirus, rare cases of myocarditis and pericarditis have been reported.

The Moderna mRNA vaccine may be more likely to cause myocarditis in men aged 12 to 29 years than other vaccines, requiring more surveillance of patients following the administration of booster shots.1 In the United States, cases of myocarditis are 1 to 2 per 100,000 people, regardless of age, with COVID-19 vaccinations only causing 0.2 cases per million people and only causing 1.4 cases of pericarditis per million people.1

Jorge Moreno, MD, assistant professor of medicine at the Yale School of Medicine, although not involved in the study, noted in a discussion with Medical News Today that the data show that cases of myocarditis and pericarditis from COVID-19 vaccinations are quite rare.2

“COVID-19, the illness, can also [cause] myocarditis, and that is much more likely than the vaccine itself [causing it],” said Moreno in the interview.2

Additionally, dosing was relevant to case numbers as well. Following patients receiving 2 doses of the Moderna vaccine, cases for anyone between the age of 12 to 39 dropped if administered 31 days following the second dose .1 For men aged 18 to 29 years, the dosing interval may need to increase to 56 days or later to ensure a decreased risk of these conditions developing.1

Often caused by viral infections such as COVID-19, myocarditis is the inflammation of the heart muscle and pericarditis is the inflammation of the 2 layered sac surrounding the heart.2 Symptoms of both diseases are present as persistent chest pain, shortness of breath, palpitations, or all 3.1 Most people recover from mild cases, but some cases of myocarditis or pericarditis have become dangerous.1

During research assessing the correlation between reported cases of myocarditis and pericarditis and vaccinations, investigators at the University of Alberta went through 46 studies and analyzed 8000 reported cases. Based on their findings, they then narrowed the age range to being between the ages of 0 to 39 years. Subsequently, they observed that cases for males over the age of 40 years were “very low to none,” according to the data.2

While the study authors noted that the data made clear that the time between dosing of the Moderna mRNA vaccine should be prolonged, they also observed that the data did not make clear if young men should avoid the Moderna vaccine entirely and be advised to get the Pfizer mRNA vaccines.1

“The FDA and the CDC here in the US did not find that the difference was substantial enough to make that recommendation [for young men to avoid the Pfizer vaccine],” Morena said in the press release.2

The study authors also noted the importance of better communication of the risks and benefits of the vaccine for young men and their families, along with more access to non-mRNA vaccine alternatives.1 Although more research regarding personal risk factors and pre-existing conditions should be done to assess potential risk further, the authors explained that due to the evolving nature of COVID-19, study findings remain limited to the investigators’ understanding of mechanistic studies and how easily diagnosable the diseases are. Additionally, although pericarditis and myocarditis often coexist, myocarditis is more easily identifiable and diagnosed using imaging and troponin protein level testing.1

The authors also noted that long term follow-up may help investigators further understand the natural history, disease recurrence, and risks of COVID-19 even with its evolving nature. To address this, multicenter prospective studies could guide researchers to understand why the vaccines cause these rare cases of heart inflammation.1


  1. Incidence, risk factors, natural history, and hypothesised mechanisms of myocarditis and pericarditis following covid-19 vaccination: living evidence syntheses and review. BMJ website. July 13, 2022. Accessed July 28, 2022.
  2. New evidence finds heart conditions extremely rare after COVID-19 vaccination. Medical News Today. July 19, 2022. Accessed July 28, 2022.
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