COPENHAGEN, Denmark — Scandinavian authorities have suspended or discouraged the use of Moderna's COVID-19 vaccine in young people because of an increased risk of heart inflammation, a very rare side effect associated with the shot.
Sweden suspended the use of Moderna for those under 30, Denmark said those under 18 won't be offered the Swiss-made vaccine, and Norway urged those under 30 to get the Pfizer vaccine instead.
Authorities in Finland are expected to announce their decision on how to handle the Moderna vaccine on Thursday.
All three countries based their decision on an unpublished study with Sweden's Public Health Agency that signals "an increased risk of side effects such as inflammation of the heart muscle or the pericardium" — the double-walled sac containing the heart.
The study added that "the risk of being affected is very small."
Earlier this year, the U.S. Centers for Disease Control and Prevention noted that a handful of young people — boys and young men in particular — have been diagnosed with heart inflammation within a week after their second vaccine dose. However, the agency said the most cases have been mild.
U.S. health agencies still recommend everyone aged 12 and older seek out a COVID-19 vaccination, as the risks posed by the virus "far outweigh the potential risks of having a rare adverse reaction to vaccination, including the possible risk of myocarditis or pericarditis."