Rare heart condition risk prompts Ontario to recommend Pfizer for young adults

The decision impacts those in the 18-24-year-old age group

A rare heart condition caused by the Moderna COVID-19 vaccine has prompted the Ontario government to recommend only the Pfizer vaccine be used in the 18 to 24-year-old age group.

The province made the decision based on an increase in the heart condition known as myocarditis and pericarditis.

Ontario’s chief medical officer of health, Dr. Kieran Moore, says it’s out of an abundance of caution and effective immediately.

The decision is based on the advice of Ontario’s children COVID-19 vaccine table, Ontario’s vaccine clinical advisory group, and Public Health Ontario.

Moore says individuals aged 18 to 24 that received Moderna as their first dose can safely take Pfizer as their second shot, adding that mixing vaccines is safe and effective.

Should residents wish to receive Moderna as their second shot and prefer to do so, the province says it can be authorized with informed consent. Moore says provincial health officials will continue to administer the Pfizer vaccine in youths aged 12 to 17, including those turning 12 in 2021.

At a technical briefing on Wednesday, health ministry officials said there have been fewer than 10 cases of individuals admitted to intensive care after developing the heart condition post-vaccination and no deaths.

They noted the symptoms are “mild” and last a “short duration of time” with most people who are hospitalized being discharged after about two days.

Between June 1 and August 7 of this year, Moore says based on 96,000 administered doses of the mRNA vaccines to males aged 18 to 24, the risk of pericarditis and myocarditis following a second Moderna dose was 1 in 5,000.

It affects only 0.1 per cent of vaccine recipients.

For those who received the Pfizer-BioNTech, the rate was one in 28,000.

The officials also noted that individuals who contract COVID-19 are 18 times more likely to develop myocarditis than those who don’t, pointing to the importance of the vaccines even in the face of adverse events.

“Based on the significantly higher risks of COVID-19 hospitalizations, ICU admissions and death among the unvaccinated those who received a first dose of the Moderna vaccine did the right thing to protect themselves, their loved ones, and communities,” the officials noted.