Both Sweden and Denmark have announced that are temporarily halting the use of the Moderna COVID-19 vaccine for younger people.
The Swedish Public Health Agency said that the suspension would last until 1 December, and that the agency had taken this step after receiving evidence that the vaccine carried an increased risk of side effects such as myocarditis (inflammation of the heart muscle) and pericarditis (inflammation of the pericardium), according to AFP.
"The Public Health Agency has decided to pause the use of Moderna's vaccine Spikevax, for everyone born in 1991 and after, for cautionary reasons," the agency said in a statement.
Instead, the age group in question is expected to receive the Pfizer/BioNTech vaccine.
The agency also noted that “the risk [of side effects] seemed especially tied to the second dose of the Moderna vaccine and was more prevalent among young men and boys, and in the weeks just following the second jab,” the media outlet reported.
Denmark declared that it was already using the Pfizer/BioNTech vaccine, Comirnaty, for people aged between 12 and 17 and it joined Sweden in recommending Pfizer/BioNTech as an alternative for other age groups.
"In the preliminary data ... there is a suspicion of an increased risk of heart inflammation, when vaccinated with Moderna," the Danish Health Authority said in a statement, quoted by Reuters.
The organisation reportedly referred to data from an as yet unpublished study, which is to be sent to the European Medicines Agency (EMA) for further assessment.