The small preprint study by the University of Ottawa Heart Institute, Canada’s “largest and foremost” heart centre, was alarming, suggesting that, based on a sample size of just 32 people, Pfizer and Moderna COVID-19 vaccinations carry an estimated one in 1,000 risk of heart inflammation.
The scientists initially estimated the prevalence of myocarditis (inflammation of the heart muscle) or pericarditis (inflammation of the outer lining of the heart) based on 32 consecutive people admitted to the Heart Institute from June 1 through to the end of July 2021 with a suspected diagnosis of post-vaccination heart inflammation.
The authors calculated that, during the same study period, a total of 32,379 doses of Pfizer and Moderna vaccines were administered in the Ottawa area. “Therefore, if our cohort captured all cases in the Ottawa area, then the incidence of myocarditis would be 0.1 per cent of all vaccine doses,” or 10 cases of myocarditis for every 10,000 doses of vaccine, they wrote.
A research letter published in JAMA involving 40 hospitals in Washington, Oregon, Montana and Los Angeles county and more than two million people who received at least one dose of a COVID vaccine estimated an incidence of one case of myocarditis in 100,000 vaccinations. In another large study out of Israel published in the New England Journal of Medicine, researchers estimated that, for every 100,000 people who get the Pfizer vaccine, one to five would likely develop myocarditis. However, the risk of heart inflammation was 11 events for every 100,000 people infected with COVID.
Late Thursday afternoon, the Heart Institute announced via Twitter that the authors have requested the paper be retracted, and that the incorrect data “vastly inflates the incidence of post-vaccine myocarditis.”
Flawed papers and early release of data have ignited controversy and emboldened conspiracy theorists throughout the pandemic. “We keep blaming crackpots and ideological mouthpieces for spreading misinformation about COVID and about vaccines, and it’s a huge problem,” said Arthur Caplan, professor of bioethics at New York University’s Grossman School of Medicine.