evidence: FDA warnings: The FDA added a warning label on the mRNA vaccines regarding serious (but rare) cases of inflammation of the heart muscle (myocarditis) and of the outer lining of the heart (pericarditis) in adolescents and young adults, more often occurring after the second dose of an mRNA vaccine. The inflammation, in most cases, gets better on its own without treatment. [...] In its recommendations for COVID vaccines, the CDC has cited a study showing the risk of cardiac complications, including myocarditis (an inflammation of the heart muscle), in males 12-17 years old was 1.8–5.6 times higher after a COVID infection compared to after COVID vaccination. [...] FDA warnings: The FDA placed a warning label on the Moderna vaccine regarding a "likely association" with reported cases of heart inflammation in young adults. This inflammation may occur in the heart muscle (myocarditis) or in the outer lining of the heart (pericarditis)—it more often occurs after the second dose of an mRNA vaccine. The inflammation, in most cases, gets better on its own without treatment.