New data confirm rare post-vaccine heart problems

Independent committee meeting with CDC released new data on heart problems and RNA vaccines

Independent committee meeting with CDC released new data on heart problems and RNA vaccines| Photo: Bigstock

Heart problems following Pfizer/BioNTech and Moderna vaccines were confirmed as rare and rapid recovery side effects by an independent advisory committee for the US Centers for Disease Control, CDC, at a meeting held on Monday (30).

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In addition to being more common after the second dose of vaccines, the committee, according to the American newspaper The New York Times, highlighted that the profile of people who had this side effect was mainly teenage boys and young men.

The rarity, according to the data released, was 14 to 20 cases of heart problems for each a million doses (second application) administered to people aged 12 to 39 years.

Benefits outweigh risks

Even among “at-risk” groups, the benefits of vaccination outweigh the possible cardiac side effects, and the data released on Monday confirm what experts had been highlighting.

Data released during the meeting by representatives of the CDC highlight Pfizer’s vaccine numbers. For every one million doses administered to 16- and 17-year-old boys, 73 cases of heart problems could be expected. However, the same doses prevented more than 56,000 cases of Covid-19 and 500 hospitalizations related to the disease.

Regarding gender differences, men tend to be at greater risk than women. Data from the Pfizer vaccine also indicate that for every one million second doses applied, there were 71.5 reported cases of myocarditis among boys aged 16 to 17 years. Among girls of the same age, 8.1 cases were identified.


The most identified heart problems were the myocarditis, or inflammation of the heart muscle, and pericarditis, inflammation of the skin covering the heart, the pericardium. The most commonly described symptom is chest pain, which may appear between the third and fifth day after vaccination.

If symptoms present after Covid-19 infection rather than after vaccinations, extra attention is needed. A new study published in the scientific journal New England Journal of Medicine, which evaluated the safety of the Pfizer/BioNTech vaccine, highlighted the risk of myocarditis associated with the immunizing agent, but also of the infection itself.

“In this study at a national mass vaccination site, the BNT162b2 vaccine was not associated with an elevated risk for the majority of adverse events examined. The vaccine was associated with an excessive risk of myocarditis (1 to 5 events per 100,000 people) The risk of this potentially serious adverse event, and many other serious adverse events, was substantially increased after SARS-CoV-2 infection,” the researchers note. The article was published on August 25th.