Several Nordic countries have paused the use of Moderna’s COVID-19 vaccine on younger people over concern the shot may be linked to a rare heart problem in young people.
Sweden’s health ministry announced on Wednesday that it was pausing injections of Moderna’s vaccine for those aged 30 and younger. Denmark announced a similar pause for those aged 18 and younger, according to Bloomberg.
Finland followed suit on Thursday. Finnish health official Mika Salminen said the government was pausing injections of Moderna’s vaccine into males aged 30 and under. All three countries cited evidence that Moderna’s vaccine may be a source of myocarditis, or heart inflammation, in young people.
“A Nordic study involving Finland, Sweden, Norway and Denmark found that men under the age of 30 who received Moderna Spikevax had a slightly higher risk than others of developing myocarditis,” Salminen said, according to Reuters.
Sweden’s health authority stopped short of putting a temporary ban on Moderna’s vaccine, but it recommended that young men under the age of 30 receive the shot developed by Pfizer-BioNTech instead.
A Moderna spokesperson defended the company’s vaccine, saying that the health risks of contracting COVID-19 outweigh the vaccine’s risk.
“These are typically mild cases and individuals tend to recover within a short time following standard treatment and rest. The risk of myocarditis is substantially increased for those who contract COVID-19, and vaccination is the best way to protect against this,” the spokesperson said, according to Reuters.
A study published Wednesday in the New England Journal of Medicine linked COVID-19 vaccines made by both Pfizer-BioNTech or Moderna to an increased chance of myocarditis in males between the ages of 16 and 29. As The New York Times reported:
The study, conducted in Israel, estimated that nearly 11 of every 100,000 males in that age group developed myocarditis, inflammation of the heart, a few days after having been fully vaccinated. That figure is higher than most earlier estimates.
Boys between 16 and 19 years of age had the highest incidence of myocarditis after the second dose, according to a second study in the journal. The risk of heart problems in boys of that age was about nine times higher than in unvaccinated boys of the same age.
The absolute risk is still very small, and the condition temporary. And studies have shown that Covid-19 is much more likely to cause heart problems compared with vaccination.
In the United States, health officials at the Centers for Disease Control and Prevention (CDC) weighed the evidence on whether Pfizer-BioNTech and Moderna’s vaccines cause myocarditis in young men in June. The CDC panel decided against pausing the vaccines over the potential side effects. The health officials decided that the benefits of getting vaccinated against COVID-19 far outweighed the risks. As the Times reported at the time:
The heart problems reported are myocarditis, an inflammation of the heart muscle; and pericarditis, inflammation of the lining around the heart. The risk is higher after the second dose of an mRNA vaccine than after the first, the researchers reported, and much higher in men than in women.
But overall, the side effect is very uncommon — just 12.6 cases per million second doses administered. The researchers estimated that out of a million second doses given to boys ages 12 to 17, the vaccines might cause a maximum of 70 myocarditis cases, but would prevent 5,700 infections, 215 hospitalizations and two deaths.