Sweden, Denmark and Finland are suspending the use of Moderna's coronavirus vaccine for young people, citing rare cases of heart inflammation.
Swedish health officials announced the halt for people aged 30 or below on Wednesday. They said a study suggests an increased risk of side effects, such as inflammation of the heart muscle and the pericardium, a sac-like structure surrounding the heart.
But the officials stressed that the risk is very small and the suspension was a precaution. They added they would use the Pfizer-BioNTech vaccine for those individuals instead.
Danish officials said they would offer only the Pfizer vaccine to people under 18.
Finnish officials said they were also suspending administration of the Moderna vaccine to men born in 1991 or later.