Study: Myocarditis is Rare Following Second COVID-19 Vaccine Dose


Greater risk for heart damaged come from coronavirus infection, and patients should not be discouraged from vaccination.

A retrospective case series published in JAMA Cardiology found that although there are rare instances of myocarditis—inflammation of the heart muscle—in younger men following COVID-19 vaccination, the greater risk for heart damage and death comes from COVID-19 infection. Although several recent studies have suggested hypersensitivity myocarditis is a rare adverse reaction to COVID-19 vaccination that health care professionals should watch for, the investigators stress that overall confidence in vaccination should not be affected.

The study reviewed 23 men in the US military hospitalized with myocarditis symptoms between January and April 2021 within 4 days of being given the second dose of a mRNA COVID-19 vaccine. Three patients had previously been infected with COVID-19, and their symptoms arose after the initial dose. However, the researchers stress that these 23 cases should be contextualized by the military’s administration of over 2.8 million doses of messenger RNA COVID-19 vaccines at that time.

“People of all ages should choose to get a COVID-19 vaccine because the risks are extremely low compared to the benefits,” said Leslie Cooper, MD, chair of the Department of Cardiology at Mayo Clinic in Florida, Jacksonville, in a press release. “Additionally, the growing body of research shows that vaccine-associated myocarditis resolves quickly in almost all cases.”

A second observational case study reviewed by the investigators followed 8 men between ages 21 and 56 years hospitalized with chest pain within 2 to 4 days of receiving their second dose of a COVID-19 vaccine, and who were diagnosed with myocarditis by laboratory and cardiac MRI. One patient had previously recovered from COVID-19, and symptoms began after the first dose. All 8 patients recovered from the effects of myocarditis and no longer suffered from chest pain at the time of review.

“Hypersensitivity myocarditis following vaccination is rare, with the exception of smallpox vaccine,” Cooper said. “The risk of myocarditis after receiving mRNA vaccine is far less than the risk of myocarditis following actual COVID-19 infection.”


Reported cases of myocarditis in younger men following COVID-19 vaccination are rare; vaccination remains important [news release]. EurekAlert; June 29, 2021. Accessed June 30, 2021.

Related Videos
Laboratory test tubes and solution with stethoscope background | Image Credit: Shutter2U -
Image credit: Andrea Izzotti
Inflation Reduction Act is shown using the text and the US flag - Image credit: Andrii |
Pharmacy Interior | Image Credit: Tyler Olson -
Male pharmacist selling medications at drugstore to a senior woman customer | Image Credit: Zamrznuti tonovi -
Pharmacist assists senior woman in buying medicine in pharmacy - Image credit: Drazen |
Pharmacy, medicine and senior woman consulting pharmacist on prescription. Healthcare, shopping and elderly female in consultation with medical worker for medication box, pills or product in store - Image credit: C Daniels/ |
Image credit: fidaolga -
Pharmacists checking inventory at hospital pharmacy- Image credit: Jacob Lund |
Young male pharmacist giving prescription medications to senior female customer in a pharmacy | Image Credit: Zamrznuti tonovi -
© 2023 MJH Life Sciences

All rights reserved.