Summary:
- The mRNA COVID-19 vaccines can rarely cause myocarditis, which is inflammation of the heart muscle. This side effect is more common in young males after the second vaccine dose.
- Researchers believe the vaccines may trigger an immune response that leads to this inflammation, but the risk is very low compared to the benefits of the vaccines in preventing severe COVID-19 illness.
- Symptoms of myocarditis include chest pain, shortness of breath, and a rapid or irregular heartbeat. Most cases are mild and resolve on their own with rest and monitoring.