Pfizer recipients were also more likely to suffer from demyelinating disease or heart inflammation, researchers found.
Dr. Julia Hippisley-Cox, a professor of clinical epidemiology at the University of Oxford’s Nuffield Department of Primary Health Care Sciences, and colleagues obtained data from a national database on COVID-19 vaccination, mortality, hospital admissions, and COVID-19 infections. They wanted to look at the link between COVID-19 vaccines from AstraZeneca, Pfizer, and Moderna with 12 outcomes, including the heart inflammation condition called myocarditis.
The population of nearly 5.2 million included 1.8 million children aged 5 to 11 and 3.3 million children aged 12 to 17.
The data examined were through Aug. 7, 2022.
In the primary analysis, researchers found 12- to 17-year-olds who received Pfizer’s vaccine were at increased risk of myocarditis, with an additional three cases per million versus the expected rate after a first dose, and an additional five cases per million after a second dose, and hospitalization with epilepsy, with an additional 12 cases per million after a second dose. Females in the age group also faced an increased risk of demyelinating disease after receiving a second dose of the vaccine.
Researchers also identified a “substantially increased risk of hospitalization with epilepsy” among females after receipt of a first dose of AstraZeneca’s shot, with 813 more hospitalizations with epilepsy than expected per million doses, and an elevated risk of appendicitis after a second dose of the vaccine, with 512 excess events per million doses.
While no excess events were found among Moderna recipients, the study lacked the power to detect statistically significant issues, due to few children in the UK receiving Moderna’s vaccine. Further, no elevated risks of the 12 issues were found among 5- to 11-year-olds.
A secondary analysis, involving matching some of the vaccine recipients to unvaccinated children, confirmed an increased risk among 12- to 17-year-olds of hospitalization with epilepsy following Pfizer vaccination, and elevated risks of severe allergic shock and appendicitis in the age group following Pfizer vaccination. No increased risks of any outcome were identified among minor Moderna or AstraZeneca recipients. But among a group of 18- to 24-year-olds studied, elevated risks of a number of conditions were found, including myocarditis, immune or idiopathic thrombocytopenia, epilepsy, and acute pancreatitis.
The study was funded by the National Institute for Health and Care Research School for Primary Care Research. Multiple authors declared conflicts of interest, including funding from Moderna and AstraZeneca. Limitations included reliance on hospital admission codes and death certificates.
Pfizer, Moderna, and AstraZeneca did not respond to requests for comment.
