Heart Problem More Common After Covid-19 Than After Vaccination, Study Finds

The research did not assess the risks specifically for young males, who are the most likely to develop the rare side effect.

The Pfizer-BioNTech Covid-19 vaccine is associated with an increased risk of myocarditis, an inflammation of the heart muscle, a large new study from Israel confirms. But the side effect remains rare, and Covid-19 is more likely to cause myocarditis than the vaccine is, scientists reported on Wednesday. The research, which is based on the electronic health records of about two million people who are 16 or older, provides a comprehensive look at the real-wold incidence of various adverse events after both vaccination and infection with the coronavirus. Although the study did not break down the myocarditis risks by age or by sex, the median age of people who developed the condition after vaccination was 25, and 19 of the 21 cases were in males, the researchers reported.