Health Canada said on Friday that it will authorize the use of the Moderna vaccine as a booster shot for those 18 and over.

"A COVID-19 booster shot is an extra dose of vaccine given after completion of the primary vaccine series," the statement says. "The booster shot is designed to help people maintain their protection against COVID-19 over time.

Health Canada said that it had received Moderna's submission to approve a booster in early October. After "thorough, independent review of the evidence, Health Canada has determined that the Spikevax [Moderna] COVID-19 vaccine booster shot meets the Department's stringent safety, efficacy and quality requirements."

The booster can be given to those over 18, and who have been vaccinated for at least six months already. The booster will be half of the regular dosage.

"Evidence continues to show that being fully vaccinated provides strong protection against serious illness, hospitalization and death from COVID-19, including against Delta variants," they explain.

Full Statement: Health Canada

Moderna barred across Europe for under 30s

Multiple European countries' health boards have warned against using the vaccine in those under 30.

Three days ago, French health authorities advised against Moderna for those under 30, due to "comparatively higher risks of heart-related problems," reports Reuters.

Germany also recently recommended Biontech/Pfizer's vaccine for those under 30 due to "more heart inflammation cases with Moderna's data."

German data revealed a "report rate for heart inflammations of 11.71 per 100,000 shots with the Moderna vaccine for men in the 18-29 age group, compared with 4.68 for the Biontech/Pfizer shot. For women, the rate was 2.95 with Moderna and 0.97 with Biontech/Pfizer," Reuters wrote.

Sweden and Denmark also decided last month that Moderna's COVID vaccine was not fit for people aged 30 and under, due again to potential heart-related side effects.

The FDA in the US is also currently investigating reports of teen heart problems caused by Moderna's vaccine.