Submitted by Ed Marcuse
Today at 1:27 p.m.
After reports surfaced of rare cases of myocarditis following COVID-19 vaccination, some parents worried that mRNA vaccines might cause heart disease in their children.
But a study published last week in Vaccine looking at more than 4 million children and young adults concludes that those who receive a Pfizer/Biotech COVID-19 vaccine have a lower risk of myocarditis (inflammation of the heart muscle), pericarditis (inflammation of the sac surrounding the heart), and death than those who do not.
“Public debate has focused on the cardiac risk of vaccination alone. Our findings reframe that discussion by comparing vaccination risk with infection-associated risk in the same healthcare network,” wrote the authors, led by researchers at SUNY Upstate Medical University.
“For patients and families, the key message is that myocarditis was rare after both exposures, but recorded myocarditis, pericarditis, and all-cause mortality were consistently more frequent after SARS-CoV-2 infection than after BNT162b2 vaccination,” they added.
‘A real but uncommon event’
The scientists conducted a retrospective, multicenter cohort study of the electronic health records of nearly 4.1 million people ages 16 to 25 from December 1, 2020, to September 30, 2025.
Participants fell into one of four groups. The first group included about 3.6 million (87.7%) vaccine- and COVID-naive young people. The second group consisted of 248,546 (6.1%) unvaccinated and infected teens and young adults.
Those who received a vaccine but never had COVID (241,152 youth [5.9%]) made up the third group. And the last group (10,677 [0.3%]) had hybrid immunity, because they had contracted COVID-19 prior to vaccination.
For patients and families, the key message is that myocarditis was rare after both exposures, but recorded myocarditis, pericarditis, and all-cause mortality were consistently more frequent after SARS-CoV-2 infection than after BNT162b2 vaccination.
Being unvaccinated and infected was associated with the highest risk of mortality, pericarditis, and myocarditis, while being vaccinated but uninfected was tied to the lowest risk of those three outcomes.
“Clinicians should communicate these findings using both absolute and relative risks: the absolute risk of myocarditis was low, but the observed risk was higher after infection than after vaccination,” the authors wrote. “This framing acknowledges vaccine-associated myocarditis as a real but uncommon event while also conveying that infection itself carries a greater cardiac risk.”