Important: VAERS reports alone cannot determine if a vaccine caused an adverse event. Reports may contain incomplete, inaccurate, or unverified information. Correlation does not equal causation.
Myocarditis (inflammation of the heart muscle) is a confirmed rare side effect of mRNA COVID-19 vaccines. Here's what the data shows — including who's most at risk, how common it is, and what outcomes look like.
Myocarditis is inflammation of the heart muscle (myocardium). It can be caused by viral infections, autoimmune conditions, and — rarely — vaccination. Symptoms include chest pain, shortness of breath, and abnormal heart rhythms.
Pericarditis (inflammation of the heart lining) is a related condition that has also been reported after COVID vaccination. Together, they're sometimes referred to as "myopericarditis."
Multiple surveillance systems worldwide have confirmed a small increased risk of myocarditis after mRNA COVID-19 vaccines (Pfizer-BioNTech and Moderna). Key findings:
A critical comparison: COVID-19 infection itself causes myocarditis at significantly higher rates than COVID vaccination. Research shows:
This risk-benefit context is important: even in the highest-risk group (young males), the risk of myocarditis from COVID infection exceeds the risk from vaccination.
VAERS contains thousands of myocarditis/pericarditis reports after COVID-19 vaccination. These reports were instrumental in identifying the safety signal early, demonstrating VAERS working as intended — detecting rare adverse events that warrant investigation.
However, raw VAERS counts overestimate the true incidence because:
Follow-up studies of vaccine-associated myocarditis show encouraging outcomes:
Based on the data, current guidance includes: