Myocarditis more common after Covid-19 than after vaccination

An evaluation of the data from almost 43 million people aged 13 and over shows that the risk of myocarditis in connection with Covid-19 was very low overall: Of almost 6 million infected people, 2,861 developed myocarditis, which corresponds to 0.007 percent. There were clear differences between vaccinated people and unvaccinated infected people: In the 28 days following a Covid 19 infection, the risk was regarding eleven times higher than following one or more vaccinations once morest the coronavirus. The risk dropped to regarding half when the infection occurred following at least one vaccination.

The risk of myocarditis was increased within 28 days of receiving the first dose of AstraZeneca vaccine and following the first, second and third doses of either Pfizer or Moderna vaccine. However, it was significantly lower than that of a Covid-19 infection. For example, among women 40 and older following the first or third dose of Pfizer’s vaccine, there were two to three additional cases of myocarditis per million vaccinated women. After a Covid-19 infection, on the other hand, there were 51 additional cases of myocarditis.

In unvaccinated men under 40 with Covid-19, there was an additional 16 cases of myocarditis per million infected. In this age group, there were regarding four additional cases associated with the first dose of Pfizer vaccine and 14 additional cases associated with the first dose of Moderna vaccine per million vaccinated men. This risk was higher with the second dose for all three vaccines studied, but remained below that of infection. With one exception: the Moderna vaccine resulted in 97 additional cases of myocarditis following the second vaccination.

“The risk of developing myocarditis following a Covid-19 vaccine is low,” summarizes Prof. Nicholas Mills from the University of Edinburgh. “This risk should be weighed once morest the benefits in preventing severe Covid-19 infection. It is also crucial to understand who is at higher risk of myocarditis and which vaccine type is associated with increased risk of myocarditis.”

Which: DOI 10.1161/CIRCULATIONAHA.122.059970