The coronavirus pandemic is not waning, even though vaccines are widely available in most of the western world.Vaccine hesitancy is an issue in some countries, like the United States, but most European nations have high vaccination rates -- especially Scandinavian countries.Last week, however, five Scandinavian countries decided to pause or limit the use of Moderna's COVID-19 vaccine after reports of side effects such as myocarditis, which is a medical term used to describe inflammation of the heart muscle.Read more below.Sweden, DenmarkAs Al Jazeera reported, Sweden and Denmark announced on Wednesday they would pause the use of Moderna’s coronavirus vaccine for younger age groups.Sweden’s chief epidemiologist Anders Tegnell -- whose approach to COVID-19 has been both criticized and praised -- said that the government would pause using Moderna for people born after 1991.Tegnell said the Swedish government would "follow the situation closely and act quickly to ensure that vaccinations against COVID-19 are always as safe as possible and at the same time provide effective protection."The Danish Health Authority said Moderna would no longer be offered to people under the age of 18.Finland, NorwayFinland joined Sweden and Denmark on Thursday, as Reuters reported.Mika Salminen, director of the Finnish health institute, said Moderna would no longer be offered to people born after 1991 because a groundbreaking new study "found that men under the age of 30 who received Moderna Spikevax had a slightly higher risk than others of developing myocarditis."Norwegian health officials, meanwhile, said that they strongly recommended men under the age of 30 opt for Pfizer's COVID-19 vaccine instead of taking the Moderna jab.IcelandIceland followed suit on Friday, according to Medical Xpress.Iceland completely suspended the use of Moderna COVID-19 vaccines, as opposed to just limiting it.A statement published on Iceland's Directorate of Health said that "as the supply of Pfizer vaccine is sufficient in the territory ... the chief epidemiologist has decided not to use the Moderna vaccine in Iceland."Eighty-eight percent of Icelanders over the age of 12 are already fully vaccinated, which means that Iceland has one of the highest vaccination rates in the world.Moderna Downplays ConcernsAs Reuters noted, a Moderna spokesperson downplayed concerns over possible vaccine side effects, stating that most people who develop heart inflammation recover soon."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.Other European countries have not yet suspended or limited the use of Moderna's COVID-19 vaccine, and it remains to be seen if they will change course in the near future.