Vaccines pose a higher risk for myocarditis than COVID-19 infection in those under 40, study shows
The overall risk of myocarditis–inflammation of the heart muscle–is higher among those under 40 after receiving a COVID-19 vaccination than it is in the weeks following a COVID-19 infection, a large new study in England shows.
The study was published on August 22, 2022 in the American Heart Association journal Circulation, and is an analysis of 42,842,345 people recieving vaccines in England between December 1, 2020 and December 15, 2021.
The data was divided by age group and by sex, and compared the risk of COVID-19-induced myocarditis with vaccine-induced myocarditis. The data showed the following:
COVID-19-Induced Myocarditis
The study found that the risk of myocarditis associated with a positive COVID-19 test was higher in people 40 years or older than in individuals younger than 40 years. There was no significant difference in risk between men and women.
Vaccine-Induced Myocarditis
- Women under 40: increased risk of myocarditis after the second dose of mRNA-1273 vaccine (Moderna)
- Women over 40: increased risk of myocarditis associated with the first and third dose of BNT162b2 vaccine (Pfizer).
- Men under 40: Increased risk of myocarditis after the first dose of Pfizer and Moderna and after the second dose of AstraZeneca.
- Men over 40: Increased risk of myocarditis after Moderna and Pfizer boosters.
Lag times between First and Second Doses
The study looked at the lag time between the first and second doses for the Moderna and Pfizer vaccines.
For Pfizer, the risk of myocarditis was greater for those who received both vaccines within 65 days compared to those with a longer lag: between 66-79 days.
This is in contrast to the Moderna vaccine. The risk of myocarditis for those with a longer lag time (i.e. >80 days) was greater than for those who received both doses of the Moderna vaccine within 65 days.
Consistent with Previous Studies
The authors indicated that their findings are consistent with 2 studies from the United States and Denmark–both of which found an increased risk of vaccine-induced myocarditis in those under 40, especially among adolescent and young males.
The authors also included a discussion on both public health and economic benefits, stating that the risks and benefits should be weighed based on age and population group.
“Vaccination against COVID-19 has both major public health and economic benefits. Although the net benefit of vaccination for the individual or on a population level should not be framed exclusively around the risks of myocarditis…” the authors said.
“[Q]uantifying this risk is important, particularly in young people who are less likely to have a severe illness with SARS-CoV-2 infection.”