Monitoring of Pfizer/BioNTech COVID-19 vaccine safety among more than 3 million US children aged 5 to 17 years flagged just 2 of 20 health outcomes among 12- to 17-year-olds—myocarditis and pericarditis, which were rare.
Myocarditis is inflammation of the heart muscle, and pericarditis is inflammation of the heart lining.
For the study, published this week in JAMA Pediatrics, a team led by a California policy research firm used three commercial healthcare claims databases to track outcomes in near real time among 3,017,352 5- to 17-year-olds who received two or three vaccine doses through mid-2022.
Outcomes were compared with historical data when possible. The researchers sequentially tested 13 of the 20 outcomes but monitored 7 only descriptively because of a lack of historical data. The Food and Drug Administration mandated the surveillance.
93% of heart conditions in boys
Among the 13 outcomes sequentially tested, only myocarditis and pericarditis met the criteria for a safety signal in any database. In the primary analysis, a signal was detected in all databases for 12- to 17-year olds after COVID-19 vaccination.
A dose-specific analysis identified a safety signal after dose two in all definitions of myocarditis or pericarditis in participants aged 12 to 17 years in all databases. Signals were detected after three doses for some definitions of myocarditis or pericarditis in 16- to 17-year-olds in one database and in those aged 12 to 15 years in another. No signals were detected in the 5- to 11-year group.
Myocarditis or pericarditis is a rare event, with an average incidence of 39.4 cases per million doses administered.
Of 153 myocarditis or pericarditis cases in the 12- to 17-year group, medical records were reviewed for 37. A total of 73.0% were confirmed myocarditis or pericarditis, with 93% of cases in boys. Nineteen patients were hospitalized, with a 2.8-day average hospital stay. The average time from vaccination to medical attention for myocarditis or pericarditis was 6.8 days.
"Myocarditis or pericarditis is a rare event, with an average incidence of 39.4 cases per million doses administered in children aged 5 to 17 years within 7 days after BNT162b2 [Pfizer] COVID-19 vaccination," the authors wrote. Previous studies have noted that the incidence of the two conditions is much higher after COVID-19 infection.