Heart complications are more likely to occur from a COVID-19 infection than an mRNA COVID-19 vaccine. A study on vaccine safety specifically comparing risk of myocarditis after vaccine vs. infection showed that among young males, the risk of heart complications (e.g., myocarditis, pericarditis) was around 2 to 6 times higher after a COVID-19 infection than the vaccine. For men ages 18 to 29, the risk was 7 to 8 times greater. Among all other groups, the risk of cardiac complications was 2.2 to 115.2 times more likely from an infection than after a vaccine. No cases of heart complications were found in children 5 to 11 after the vaccine. Myocarditis happens when your heart muscle becomes inflamed. Another condition known as pericarditis happens when the outer lining of the heart is inflamed. Myocarditis can be serious, but these cases are often mild and get better without any treatment. Symptoms can include abnormal heart rhythms, difficulty breathing, and chest pain. The CDC has systems set up to look for safety concerns with the vaccines. These systems are watched closely.