False claim that study found myocarditis only after vaccine, not COVID-19 | Fact check

The claim: Study shows myocarditis and pericarditis only appear after COVID-19 vaccination, not after COVID-19 infection

A June 24 Facebook post (direct link, archive link) shows an image of COVID-19 vaccine vials.

“Oxford University: Myocarditis and Pericarditis Only Appear After COVID Vaccination, Not After COVID Infection," read on-screen text included in the image.

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Our rating: False

The Oxford study referenced in the post did not show that heart inflammation doesn't occur after COVID-19 infection, according to one of the study's authors. The study compared outcomes between vaccinated and unvaccinated patients, not between those vaccinated and those infected with COVID-19. It also only included children and adolescents.

Study author says claim is inaccurate

The caption and image in the Facebook post match the headline and header image of a June 2 article published by the Gateway Pundit. The article links to a preprint paper published by researchers from the University of Oxford and other institutions.

The paper reports results from a study designed to analyze "the safety and effectiveness of first and second dose (of the Pfizer) COVID-19 vaccination in children and adolescents in England." It includes a message saying the research hasn't yet been peer-reviewed and "should not be used to guide clinical practice."

Edward Parker, a co-author on the paper, told USA TODAY that the social media post misrepresents the study.

"The claims are misinterpreting the study, which compared vaccinated versus unvaccinated individuals, not vaccinated versus infected individuals," he said in an email. "The latter would have needed a different study design."

The study only documented myocarditis and pericarditis, rare inflammatory heart conditions, in the vaccinated group, but the incidences were very rare − 27 cases per million after the first dose of the vaccine and 10 cases per million after the second dose. Parker said the study did not determine whether or not the cases of heart inflammation were caused by the vaccine.

"Assessing whether they are causally linked with vaccination is very challenging as there are other possible explanations for why these cases may have been recorded," he said. "For example, the vaccinations in our study occurred after myocarditis and pericarditis had been discussed in the media, so this increased awareness may have caused different patterns of health-seeking behavior and diagnosis after vaccination."

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He added that the study results are not applicable to adults because the study only included children and adolescents.

Other studies have shown – contrary to the supposed study results in the post – that heart inflammation can occur both after COVID-19 infection and COVID-19 vaccination in children and adults, though it is rare. In a group of 43 million people, aged 13 and older, an American Heart Association study found myocarditis is more common after COVID-19 infection than after vaccination.

USA TODAY reached out to the Facebook user who shared the post for comment but did not immediately receive a response.

The claim was also debunked by AAP.

Our fact-check sources:

• Edward Parker, July 30, Email exchange with USA TODAY
• American Heart Association Journals, Aug. 22, 2022, Risk of Myocarditis After Sequential Doses of COVID-19 Vaccine and SARS-CoV-2 Infection by Age and Sex
• Children's Hospital of Philadelphia, Dec. 14, 2021, Myocarditis and COVID-19: Get the Facts
• Nature, 2024, Myocarditis associated with COVID-19 vaccination
• MedrXiv, May 20, OpenSAFELY: Effectiveness of COVID-19 vaccination in children and adolescents

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