The vast majority of cases occur in young men, ages 16 to 24, according to the CDC. The agency did not have data available on the total number of cases in young adults 24 and younger, but it estimates there have been 52.4 cases and 56.3 cases per million doses of Pfizer’s and Moderna’s vaccines, respectively.
Symptoms of myocarditis include:
- Chest pain
- Shortness of breath
- Feelings of having a fast-beating, fluttering or pounding heart
A study by Canadian researchers published Monday in the Journal of the American College of Cardiology found that men younger than 40 who got the Moderna vaccine had the highest risk of heart issues, usually within 21 days after the second dose. The study was observational, meaning it doesn’t prove cause and effect but it is one of only a few studies to compare the risk of myocarditis between the Pfizer and the Moderna vaccines.
From 14 December 2020 through 31 May 2022 (persons 18–39 years) and 20 August 2022 (persons 5–17 years), 320 potential cases of myocarditis/pericarditis were identified 1 to 98 days after 6 992 340 vaccine doses as part of primary series COVID-19 vaccination, with 224 (70%) verified. Of these, 137 (61%) occurred 0 to 7 days after vaccination; 18 were after the first dose (of 3 562 311 doses administered) and 119 were after the second dose (of 3 430 029 doses administered).
In all age groups, incidence per million doses 0 to 7 days after vaccination was numerically higher in male than in female persons and after dose 2, although confidence intervals were wide and overlapped across sex for some age groups. Incidence was highest for male adolescents ages 12 to 15 years and 16 to 17 years following dose 2.
From 24 September 2021 through 20 August 2022, 101 potential cases of myocarditis/pericarditis were identified 1 to 98 days after 1 848 723 first booster doses, with 77 (76%) verified with a median onset of 4.5 days after vaccination; 39 cases (51%) were verified in the first week versus 38 during the subsequent 13 weeks.
In all age groups, incidence 0 to 7 days after first booster was higher for male compared to female persons, with adolescent males having the highest incidence in 16- to 17-year-olds and in 12- to 15-year-olds. In adults for whom both vaccine products were available, post-booster incidence was higher in male than in female adults and higher in males aged 18 to 29 compared to males aged 30 to 39.
Thousands of American teenagers may have suffered heart inflammation after getting a Covid jab, a study suggests.
Researchers found up to one in 7,000 boys aged 12 to 15 years old developed myocarditis after receiving the Pfizer vaccine.
The condition — which is mild for most but can cause a recurrent heart palpitation in rare cases — was most common after the second dose.