Norway and Sweden Pause Moderna COVID-19 Shot in Young Adults

Norway and Sweden are advising men younger than age 30 and all people under 18 years old to avoid taking the Moderna COVID-19 vaccine because of its rare association with myocarditis and endocarditis.

Analyses of reported adverse reactions from the U.S. “have suggested that myocarditis may be more frequent when using Moderna’s vaccine as a second dose” than using the Pfizer-BioNTech vaccine, “but the numbers have been small and therefore uncertain,” said Geir Bukholm, deputy director general at the Norwegian Institute of Public Health.

Nordic countries are collaborating on several large health registry analyses to detect and investigate rare COVID-19 vaccine side effects. While the combined data aren’t complete, Norwegian data suggest an increased incidence of cardiac inflammation after using the Moderna vaccine as a second dose.