A study of nearly 1.7 million children and adolescents in England documented 18 cases of myocarditis and pericarditis — heart muscle and heart lining inflammation — and every one occurred in a young person who had received the Pfizer/BioNTech Comirnaty COVID-19 vaccine, Augsburger Allgemeine reported, citing the study’s findings. No cases appeared in the unvaccinated comparison groups during the analysis period.
All 18 cases were mild, with no serious outcomes, and the study’s authors emphasized that such inflammation can also occur independently of vaccination. They concluded that the absence of cases in unvaccinated groups does not mean heart inflammation cannot happen without a shot.
Breakdown of the 18 Cases by Age and Dose
The cases split into 3 myocarditis cases and 15 pericarditis cases:
- Myocarditis: All 3 cases occurred in adolescents aged 12–15 after the first dose; zero after the second dose. No cases occurred in children aged 5–11 after either dose.
- Pericarditis: Among adolescents aged 12–15, 9 cases followed the first dose and 3 followed the second. Among children aged 5–11, 3 cases followed the first dose and none followed the second.
The researchers identified an association between the Comirnaty vaccine and an elevated risk of these heart inflammations, but described the cases as rare and mild.
Vaccine Risk Compared With COVID-19 Infection Risk
The authors weighed the risk against the vaccine’s benefit: for adolescents, the reduction in the risk of COVID-related hospitalization outweighed the increased risk of heart inflammation. For children aged 5–11, the reduction in hospitalization risk was smaller than the increased pericarditis risk.
A separate British analysis, published in The Lancet Child & Adolescent Health, found the risk of myocarditis or pericarditis after COVID-19 vaccination is significantly lower than the risk after a COVID-19 infection itself.
Regulators Flagged the Link in 2021
The European Medicines Agency (EMA) and Swiss drug regulator Swissmedic both informed the public in mid-2021 about a possible link between the Comirnaty and Spikevax vaccines and cases of myocarditis and pericarditis. Young men were predominantly affected, with cases typically appearing within the first weeks after vaccination. Relative to the number of doses administered, case numbers were very small, and Swissmedic rated the benefit-risk balance of the vaccines used as positive.
Questions Readers Are Asking
Can heart inflammation happen without vaccination?
Yes. The study’s authors noted that myocarditis and pericarditis have many causes, most tied to bacterial or viral infections, so the zero cases in unvaccinated groups during the analysis window do not prove the condition cannot occur without a vaccine.
Which age group saw the most cases?
Adolescents aged 12–15 accounted for the majority: all 3 myocarditis cases and 12 of the 15 pericarditis cases occurred in that group.
Did any case turn serious?
No. All 18 documented cases in the vaccinated groups ran a mild course with no serious consequences.