Boys ages 12 to 15 have a small but increased risk of heart problems after receiving a second dose of the Pfizer-BioNTech vaccine, Israe...
Boys ages 12 to 15 have a small but increased risk of heart problems after receiving a second dose of the Pfizer-BioNTech vaccine, Israeli researchers reported Wednesday.
Myocarditis, or inflammation of the heart muscle, occurred in one of 12,361 boys in this age group within a week of receiving a second dose, according to the study.
The cases were mild and the side effect remains infrequent. What’s more, several studies have shown that the risk of myocarditis after Covid is much higher than after vaccination.
Still, the Israeli figure is higher than the Centers for Disease Control and Prevention’s estimate of one case per 16,129 vaccinated teenagers between the ages of 12 and 17. Israeli researchers Previously reported that nearly 11 in 100,000 boys and men aged 16-29 were at increased risk of myocarditis after vaccination.
Although the new results are only based on the Pfizer-BioNTech vaccine, other studies have shown that the incidence of myocarditis may be higher with the mRNA vaccine made by Moderna. Myocarditis can manifest as chest pain, shortness of breath, and the feeling of having a fast, pounding or pounding heart, According to the CDC.
Some European countries have suspended the use of the Moderna vaccine in adolescent males due to the risk. In the United States, only the Pfizer-BioNTech vaccine is licensed for use in adolescents and children 5 years of age and older.
Concern about heart inflammation may have prompted the Food and Drug Administration to ask Pfizer-BioNTech and Moderna to enroll more children in their vaccine trials. Even so, Pfizer’s vaccine trial only included 567 boys aged 12 to 15 – too few to detect uncommon side effects.
The new study tracked hospitalizations for myocarditis from June 2 to October 20, 2021, through an Israeli Ministry of Health surveillance system. During this period, 404,407 adolescents aged 12 to 15 received one dose of vaccine and 326,463 adolescents received a second dose.
The researchers found 18 reports of hospitalizations for myocarditis. They excluded two of the cases because of “reasonable alternative diagnoses” and two others because they occurred 46 and 70 days after the second dose – too long after vaccination to be linked, the researchers said.
Of the remaining 14 cases, one was in an unvaccinated teenager, one in a teenager who received the first dose of vaccine within 21 days, and 12 cases within a week of the second dose. The results were published in The New England Journal of Medicine.
All cases were clinically mild and the adolescents were hospitalized for an average of three days. None were readmitted during the 30 days of follow-up.
The researchers estimated that myocarditis occurs in 0.56 out of 100,000 adolescent males after a first dose and in 8.09 out of 100,000 after a second dose. The corresponding risk in girls of this age was negligible.
The study may have underestimated the risk of myocarditis, as the researchers only looked at boys hospitalized with the condition.
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