COVID Booster Shots Carry ‘Increased Myocarditis Risk’ for Young Adults: Nordic Study

Among males, a third dose of the Pfizer or Moderna vaccine was associated with an ‘increased incidence rate of myocarditis’ within 28 days.

A woman receives a Moderna COVID-19 vaccine in a file photograph. Johanna Geron/Reuters

Booster vaccination against COVID-19 is linked to a higher risk of heart inflammation among adolescents, according to a recent study using data from several Nordic nations.

The peer-reviewed study, published in the European Heart Journal on Feb. 15, evaluated the risk of myocarditis among 12- to 39-year-olds after receiving COVID-19 mRNA booster vaccination. Myocarditis refers to an inflammation of the heart muscle myocardium. The study analyzed data from 8.9 million young adults from four nations: Denmark, Finland, Norway, and Sweden.