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Does the COVID-19 vaccine cause myocarditis?

Yvonne A. Maldonado, MD, FAAP


​​​​​You may have heard news about a small number of teens and young adults who experienced a heart inflammation (called myocarditis) after getting the COVID-19 vaccine. Most felt better after getting ​anti-inflammatory medicines and rest.

The Centers for Disease Control and Prevention (CDC) is studying these cases to see if there is any link to the vaccine. This kind of ongoing monitoring is standard with all new vaccines to make sure they are safe. Fortunately, the number of myocarditis cases reported in young people after vaccination doesn't appear any larger than what's normally seen in people this age without the vaccine.

However, we want to make sure that these cases aren't anything more than coincidence. If the reported myocarditis is related to COVID-19 vaccines, it's most likely a rare side effect since the vaccines have been given since December 2020 to at least 4 million adolescents between ages 16 and 18; the condition has not been reported to be associated with vaccination during that time.

What is myocarditis?

Myocarditis is the inflammation of the heart muscle. It happens when the body's immune system reacts to an infection or some other trigger. In more than half of cases, no cause is identified. Symptoms can include abnormal heart rhythms, shortness of breath, or chest pain. The recent reports of myocarditis after COVID-19 vaccination were seen:

  • mostly in teens age 16 or older and young adults,

  • more often in males than females,

  • more often following dose 2 than dose 1, and

  • typically within 4 days after vaccination.

What we do know: COVID-19 vaccines save lives

While we don't yet know what is causing these cases of heart inflammation, we do know that children can and do become infected with COVID and some get seriously ill. Thousands of children have been hospitalized, and hundreds have died after being infected with the virus. Some children who have recovered continue to experience lingering symptoms. In fact, COVID-19 itself is known to cause myocarditis.

Since December 2020, almost a third of a billion COVID-19 vaccine doses have been administered in the United States. The American Academy of Pediatrics, as well as the CDC, continues to recommend COVID-19 vaccination for people 12 years and older. They are proven to be very effective at preventing COVID-19 and are truly life-saving. If you or your children are eligible for the vaccine, I encourage you to plan to get it ​as soon as possible.


The potentially rare side effect of myocarditis pales in comparison to the potential risks of COVID-19. The vaccines currently available for anyone age 12 and older. If you have any concerns, don't hesitate to talk with your pediatrician.

More information​

Yvonne A. Maldonado, MD, FAAP

​Yvonne A. Maldonado, MD, FAAP, is Professor and Chief of the Division of Infectious Diseases, Department of Pediatrics at Stanford University School of Medicine, Stanford, California. She is also the Senior Associate Dean for Faculty Development and Diversity at the Stanford School of Medicine. With the onset of the COVID-19 pandemic she has over 10 clinical, epidemiology and laboratory-based studies in this area and is involved in epidemiologic modeling at the university, state and national level. She is the Chair of the American Academy of Pediatrics Committee on Infectious Diseases. Dr. Maldonado has published over 200 peer-reviewed articles in scientific journals and is co-editor of the textbooks "Remington and Klein Infectious Diseases of the Fetus and Newborn Infant" and "Report of the American Academy of Pediatrics Committee on Infectious Diseases (Red Book)."

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The information contained on this Web site should not be used as a substitute for the medical care and advice of your pediatrician. There may be variations in treatment that your pediatrician may recommend based on individual facts and circumstances.
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