Out of what it’s calling “an abundance of caution,” the Ontario government is recommending that people 18 to 24 be immunized with the Pfizer vaccine instead of the one made by Moderna, due to concerns of the higher risk of myocarditis or pericarditis in people — particularly males — in that age group.
Myocarditis and pericarditis are, respectively, inflammations of the heart muscle or its outer lining. The symptoms have generally been mild but can lead to severe outcomes, including hospitalization. To date, there have been no deaths associated from myocarditis or pericarditis due to vaccination in Ontario. It remains a rare outcome: approximately one in 5,000 cases for males who received a second Moderna dose, compared to a rate of one in 28,000 for people who received the Pfizer vaccine.
According to Ontario data, 88 per cent of cases of myocarditis/peridcarditis occur within the first week after a second dose, and people who have gone several weeks after their second dose of a Moderna vaccine without any symptoms such as chest pains, shortness of breath, irregular heatbeats, or fatigue do not need to worry.
Government officials speaking on background in a technical briefing conceded that this announcement could cause more anxiety and vaccine hesitancy even for people outside the specific 18 to 24 age group. They emphasized that these conditions are still an extremely rare outcome and that the possibility of severe outcomes from a COVID-19 infection among unvaccinated people are uniformly worse than the risks from the vaccines.
Ontarians can still receive a Moderna dose if they prefer, provided they can give informed consent.
Read the full presentation below.