FDA Delays Moderna Covid-19 Vaccine for Adolescents to Review Rare Myocarditis Side Effect

The Food and Drug Administration is delaying a decision on authorizing Moderna Inc.’s Covid-19 vaccine for adolescents to assess whether the shot may lead to heightened risk of a rare inflammatory heart condition, according to people familiar with the matter.

After four Nordic countries strengthened their stances against giving Moderna vaccines to younger adults last week, the FDA has been taking another look at the risk of the condition, known as myocarditis, among younger men who took Moderna’s vaccine, especially compared with those who received the vaccine from Pfizer Inc. and BioNTech SE, the people said.