Study claiming 1/1,000 risk heart damage after vaccine got calculation wrong
Open database denominator was erroneous
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.
Except the “incidence calculation” was off. Way off. And it wasn't corrected or withdrawn before creating considerable traffic on Twitter.
“That our data should suggest a tenfold higher incidence (than recent reports) seems surprising,” the Ottawa researchers wrote in the uncorrected version of the study posted to a preprint site Sept. 16.
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.
The researchers said the data collected on vaccine doses came from an Ottawa Public Health open database.
Except their denominator was wrong.
Ottawa Public Health confirmed to the National Post that, during the study period, more than 833,000 MRNA (Pfizer of Moderna) COVID-19 vaccinations were administered in Ottawa.
The adjusted incidence is about four per 100,000 doses, which is within the range of recent studies, and vastly lower than the initial estimate.
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.
“Ottawa Public Health was not involved in the study and did not provide the data that was used for the calculation of the incidence or estimation of the denominator,” the department said in an email.
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.”
In an interview Wednesday, Dr. Peter Liu, chief scientific officer at the University of Ottawa Heart Institute and one of the study's authors, said the risk calculation had been corrected and sent to the preprint server, but that the new data hadn't yet been posted.
Liu said the researchers had incomplete data on the total doses of MRNA vaccines for the entire region of Ottawa. “These numbers were getting updated, so we didn't get the full numbers.”
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. “But there have been a not-insignificant number of instances where mainstream science has gotten things wrong,” and which critics pick up on, instantly, Caplan said.
The timing of the myocarditis paper is also concerning, given that many parents will soon face the issue of getting children ages five to 11 vaccinated, which Caplan called “hugely important.”
Josh Greenberg, professor of communication and media studies at Carleton University, said the paper, which lists 12 authors, is being “weaponized” by prominent anti-vaxxers. “It is either being intentionally used by those sources who work very hard to undermine COVID vaccination efforts or, at the very least, establishes enough doubt and uncertainty that will cause people who may have legitimate questions about the safety and efficacy of the vaccine to refuse it altogether.”
Liu said he doesn't usually post preprint versions of his studies, “but this is something that's very new, and we have a lot of people interested in this,” he said. “We are advisers to the government on this, as well. So, we post our data. We have very indepth information on this.”
In the Ottawa study, of the 30 people admitted to hospital, symptoms resolved quickly in all cases, most were treated with high dose aspirin or the gout drug colchicine, most were sent home within a few days, and there were “no major adverse cardiac events” or deaths.
The median age of those in the study was 33, most (29 out of 32) were males and most developed symptoms after their second vaccine. Everyone received at least one dose of Pfizer or Moderna. Symptoms like chest pain, breathlessness, fever and chills started within a day-and-a-half of a dose.
Health Canada recently updated the label for the Pfizer and Moderna shots, warning of rare reports of myocarditis, but experts have continued to stress that the risk of heart inflammation is far higher from COVID-19 than from vaccines.
As of Sept. 10, 718 cases of myocarditis and pericarditis following COVID vaccination had been reported to Health Canada.
While Pfizer said it's aware of “very rare reports” of myocarditis and pericarditis, predominantly in teenage boys and young adults, after vaccination, “only a small number of people will experience it after vaccination,” and people typically rapidly improved with “conservative treatment.”