Some countries have halted altogether or are giving only one dose of COVID shots based on so-called mRNA technology to teens following reports of possible rare cardiovascular side effects.

Europe’s drug regulator said in July it had found a possible link between a very rare inflammatory heart condition and COVID-19 vaccines from Pfizer/BioNTech and Moderna (MRNA.O). read more

However, the benefits of mRNA shots in preventing COVID-19 continue to outweigh the risks, European and U.S. regulators and the World Health Organization have said.

Here are some of the steps some countries are taking:

CANADA

The Public Health Agency of Canada said data suggested that reported cases of rare heart inflammation were higher after Moderna’s COVID-19 vaccine compared with the Pfizer/BioNTech shots. read more

SWEDEN

Sweden paused the use of Moderna’s COVID-19 vaccine for younger groups, citing data from a yet unpublished Nordic study. read more

The Swedish health agency said it would pause using the shot for people born in 1991 and later as data pointed to an increase of myocarditis and pericarditis among youths and young adults that had been vaccinated.

DENMARK

The Danish Health Agency said on Friday that it was continuing to offer Moderna’s COVID-19 vaccine to under-18s, and that a statement on Wednesday suggesting a suspension had in fact been a miscommunication. read more