HealthDay News — Male adolescents and young adults have the highest risk for myocarditis after mRNA COVID-19 vaccination, with an increased risk for Moderna vaccines, according to an updated review published online July 13 in The BMJ.
Jennifer Pillay, from the University of Alberta in Edmonton, Canada, and colleagues conducted a living evidence synthesis and review to examine the incidence rates and risk factors for myocarditis and pericarditis after mRNA vaccination against COVID-19. Data were included from 46 studies.
The researchers found that male adolescents and male young adults had the highest incidence of myocarditis after mRNA vaccines (age 12 to 17 years: range, 50 to 139 cases per million; 18 to 29 years: range, 28 to 147 cases per million). The incidence of myocarditis after vaccination with BNT162b2 could be fewer than 20 cases per million among girls and boys aged 5 to 11 years and women aged 18 to 29 years. Very low-certainty evidence was seen for incidence after a third dose of an mRNA vaccine. Incidence of myocarditis was probably higher after vaccination with mRNA-1273 versus BNT162b2 among those aged 18 to 29 years. The incidence of myocarditis or pericarditis after dose 2 of an mRNA vaccine might be lower when administered ≥31 versus ≤30 days after dose 1 among individuals aged 12 to 17, 18 to 29, and 18 to 39 years based on low-certainty evidence.
“As the COVID-19 pandemic enters its third year, continued surveillance of myocarditis after mRNA vaccines, especially in younger ages, after dose three (and subsequent doses) and in previous cases is needed to support continued decision making for COVID-19 boosters,” the authors write.