There have been very rare reports of myocarditis (inflammation of the heart muscle) and pericarditis (inflammation of the lining around the heart) within 7 days of getting an mRNA vaccine. Most reported cases were mild and got better with treatment.
The inflammation can cause shortness of breath, chest pain or pressure, or a very fast or abnormal heart rate. Get medical help right away if you have any of these symptoms.
Research has shown that the risk of these rare events after additional doses is lower than the risk after the second dose for any type of mRNA vaccine. Moderna and Pfizer-BioNTech COVID-19 vaccines have a similar low risk of myocarditis and pericarditis.
Research has shown that children age 5 to 11 years have a lower risk of these events than adolescents and adults.
In clinical trials for both the Pfizer-BioNTech and Moderna vaccines, there were no reports of myocarditis or pericarditis in children age 6 months to 5 years.
Research is still happening to learn more about the risk of these rare events after a getting updated versions of the mRNA COVID-19 vaccines.
It is not known if having a history of myocarditis or pericarditis puts you at higher risk of having these rare events after a COVID-19 vaccine. Talk to your doctor before you get a dose of COVID-19 vaccine if:
- You had myocarditis or pericarditis within 6 weeks of getting a COVID-19 vaccine.
- You have a history of myocarditis or pericarditis and you have questions about getting a COVID-19 vaccine.
Your risk of getting seriously ill from COVID-19 is much higher than your risk of having a rare event after these vaccines.