CDC data has found that boys and young men, aged 12 to 24, have a heightened risk of myocarditis (inflammation of the heart) after COVID-19 vaccination. However, the cases are rare, relatively mild, and almost always resolve, according to CDC data. In a COVID-19 safety data presentation in June, CDC staff scientists reported that its vast vaccine safety monitoring systems indicated that in males 12–24, there are 27 myocarditis cases per million doses of COVID-19 vaccine administered (roughly one case in 37,000 doses). In cases identified during 2021, 83 percent recovered within three months, with more than 90 percent recovering within the year. The monitoring data found no instances of cardiac transplant or death from COVID-19 vaccination.

While anti-vaccine activists have seized on this minor risk from vaccination, health experts note that the risk of myocarditis and other inflammatory conditions from a COVID-19 infection is significantly greater than the risk from vaccination. Exact estimates vary, but one CDC study in 2021 found that people with COVID-19 infections had a 16-fold higher risk of myocarditis than people without the infection. Specifically, the study estimated that there were 150 myocarditis cases among 100,000 COVID-19-infected patients versus just nine myocarditis cases among 100,000 people without COVID-19 infections and who were also unvaccinated. Similar to what’s seen with vaccination, the study found that young males were most at risk of myocarditis.

Kennedy’s allies attack on COVID-19 shots

Kennedy and his allies, like Milhoan, have consistently inflated the risk of myocarditis from COVID-19 vaccination, with some claiming without evidence that they have caused sudden cardiac arrest and deaths in young males, though studies have found no such link. In 2022, Milhoan and fellow ACIP member and conspiracy theorist Robert Malone were featured in a viral social media post suggesting that 50 percent of college athletes in the Big Ten athletic conference had myocarditis linked to COVID-19 vaccines, which could lead to deaths if they played. But the two were referencing a JAMA Cardiology study that examined subclinical myocarditis in Big Ten athletes after COVID-19 infection—not vaccination. In fact, researchers confirmed for an AFP fact check that none of the athletes in the study were vaccinated. And the rate of subclinical myocarditis in the group was 2.3 percent, not 50 percent.