Can the COVID-19 Vaccine Cause Myocarditis?

Reviewed 3/21/2024

A Children’s-led study confirms that heart inflammation or myocarditis is a very rare side effect in kids who receive the COVID-19 mRNA vaccine. Find out why the benefits of vaccination still outweigh the risks.


Vaccine in Kids and Myocarditis Facts

Throughout the pandemic, parents have been forced to make some tough calls about how best to keep their kids safe and well. The most challenging decision for some: to vaccinate or not to vaccinate. The consensus among scientists and infectious disease experts worldwide is that the COVID-19 vaccine is safe for kids ages 6 months and older. However, like any vaccine, there are risks.

One of these risks is myocarditis, or inflammation of the heart muscle, according to a study led by Children’s Heart Center cardiologist Matthew Oster, MD. “Myocarditis typically occurs after a viral illness,” explains Dr. Oster. “However, our analysis confirmed that the mRNA COVID vaccine can also be a trigger for myocarditis in rare instances.”

“Rare” is the key word here. According to the study, which involved a review of data collected via the Vaccine Adverse Event Reporting System (VAERS) from Dec. 14, 2020 to Aug. 31, 2021, there were 1,991 confirmed cases of myocarditis. This was out of approximately 192.4 million people ages 12 and up, all of whom were vaccinated with at least one dose of either the Pfizer or Moderna mRNA vaccine. In other words, there's less than a 0.01 chance of contracting myocarditis after vaccination.


Myocarditis After COVID-19 Infection

COVID-19 is a viral infection that can cause heart problems in some instances. Kids and teens sick with COVID-19 have experienced the following heart problems after infection:

  • Myocarditis resulting from active COVID-19 infection
  • Heart problems as a result of multisystem inflammatory syndrome in adults (MIS-A) and in children (MIS-C), which causes inflammation in different parts of the body

Heart inflammation more common in boys

While the overall number of cases of vaccine-triggered myocarditis is minimal, the study showed that there are some kids who are at greater risk. “We found that the risk for myocarditis was highest in adolescent and young adult males, particularly those 16 to 17 years old,” says Dr. Oster.

In fact, males accounted for around 82 percent of all cases. A majority of them developed symptoms of myocarditis after their second shot, most often within seven days of vaccination.

After a child receives the COVID-19 vaccine, it’s not uncommon for them to experience side effects like headache, muscle pain and fatigue. But parents should be on the lookout for other, more serious symptoms that could be a sign of myocarditis

The symptoms most commonly reported by people ages 12 years and older include:

  • Chest pain
  • Shortness of breath
  • Fast, fluttering or abnormal heartbeat

Most common symptoms of myocarditis for children younger than 12 years old include:

  • Irritability
  • Vomiting
  • Loss of appetite or inability to eat
  • Lethargy
  • Rapid, shallow breathing

Should your child experience any unusual symptoms, especially within one week of receiving the COVID-19 vaccine, contact your pediatrician. Early diagnosis and treatment of myocarditis typically results in more mild cases and shorter recovery time.

Kids diagnosed with vaccine-associated myocarditis are hospitalized for observation and treated with anti-inflammatory medication. In almost all cases reported, kids’ symptoms resolved before they left the hospital. “When a child gets myocarditis as a result of getting sick from a viral infection, they sometimes require more complex treatments, like a ventricular assist device or heart transplant,” says Dr. Oster. “But unlike these cases of myocarditis caused by a virus, the heart inflammation that has resulted post-COVID vaccination appear to be effectively managed with just pain medication.”

While long-term follow-ups are still needed to determine outcomes over time, initial surveys of cardiologists and healthcare providers found that 91 percent indicated their patient was fully or probably recovered.

Can My Child Return to Sports after Myocarditis?

Getting kids back to normal activities after any illness is a priority. But safety is key. The American Heart Association and American College of Cardiology recommend that kids diagnosed with myocarditis after COVID-19 vaccination wait three to six months after recovery before participating in athletics. “These kids will need additional testing to ensure their hearts are fully recovered before returning to competitive sports, but the hope and expectation is that all will be able to return to full activity,” says Dr. Oster.

As with any medical decision you make for your child, it’s important to weigh the pros and cons of COVID-19 vaccination. Here are some key points to keep in mind:

  • All COVID-19 vaccines underwent rigorous testing prior to being authorized by the FDA, and vaccine safety continues to be monitored.
  • Millions of people worldwide have received the mRNA vaccine without serious side effects.
  • Serious side effects resulting from the vaccine—including myocarditis—are extremely rare.
  • In most cases of vaccine-associated myocarditis, kids recovered completely after receiving medication.
  • The risks of medical complications resulting from a COVID-19 infection are much greater than the risk of side effects from the vaccine.

The bottom line: The best way to protect your kids and the rest of your family from serious COVID-19-related illness is for everyone eligible to get vaccinated and boosted.

This content is general information and is not specific medical advice. Always consult with a doctor or healthcare provider if you have any questions or concerns about the health of a child. In case of an urgent concern or emergency, call 911 or go to the nearest emergency department right away. Some physicians and affiliated healthcare professionals on the Children’s Healthcare of Atlanta team are independent providers and are not our employees.

Matthew Oster, MD, a Pediatric Cardiologist at Children’s Healthcare of Atlanta, is board certified in pediatric cardiology. Dr. Oster earned his Doctor of Medicine at University of Pennsylvania School of Medicine. He completed his residency at the University of California–San Francisco Medical Center, followed by a fellowship at Children’s and Emory University School of Medicine.