Large 4.1m FDA Study Confirms Myocarditis/Pericarditis and Seizure Safety Signals in Young People—Should Boosters Continue?

Researchers from the Food and Drug Administration (FDA) as well as major pharmacy retail chains, payers and data-based companies investigated whether statistical signals detected health outcomes post-vaccination with ancestral COVID-19 vaccine in children aged 6 months to 17 years. Part of an active safety monitoring program involving COVID-19 vaccination, a bid to detect rare outcomes not identified in clinical trials involved researchers from the FDA, CVS Health/Aetna Blue Bell, Optum Epidemiology (part of UnitedHealthcare), IQVIA, Acumen LLC and Carelon Research led by Patricia C. Lloyd, Ph.D., ScM of the FDA. An FDA-sponsored clinical trial with results published in the journal JAMA Network, the cohort study evaluated 21 prespecified health outcomes post-exposure before early 2023 to Pfizer (BNT162b2), Moderna (mRNA-1273), or Novavax (NVX-CoV2373) ancestral monovalent COVID-19 vaccines in children aged 6 months to 17 years by applying a near-real-time monitoring framework using healthcare data from three commercial claims databases in the US (Optum [through April 2023], Carelon Research [through March 2023], and CVS Health [through February 2023]). Lloyd and colleagues analyzed and reported on increased rates of each outcome after vaccinations were compared with annual historical rates from January 1 to December 31, 2019, and January 1 to December 31, 2020, as well as between April 1 and December 31, 2020. The study involved 4,102,016 vaccinated enrollees aged 6 months to 17 years. 2,058,142 (50.2%) of the total were male, and 3,901,370 (95.1%) lived in an urban area. Thirteen of 15 sequentially tested outcomes failed to meet the threshold for a statistical signal. However, as was reported on with the group&rsquo;s preprint, statistical signals were detected for myocarditis or pericarditis after BNT162b2 vaccination in children aged 12 to 17 years plus seizure after vaccination with BNT162b2 and mRNA-1273 in children aged 2 to 4 or 5 years. Conducting a post hoc sensitivity analysis, the study team reported that the statistical signal for seizure was observed only after exposure to the Moderna vaccine (mRNA-1273) when 2019 background rates were selected; no statistical signal was observed when 2022 rates were selected.
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