On January 9, 2026, the FDA notified flu vaccine manufacturers of new safety information requiring label updates to warn of increased febrile seizure risk in children 6 months through 4 years old.1
Studies from 2023-2024 and 2024-2025 flu seasons using self-controlled case series analyses showed significantly elevated risk on day 0-1 post-vaccination compared to days 8-63.1
For quadrivalent (2023-2024) vaccine, IRR was 1.97 (95% CI: 1.09-3.54), with 21.2 excess episodes per million doses; for trivalent (2024-2025), IRR was 2.94 (95% CI:
1.72-5.01), with 44.2 excess episodes per million doses.1
Manufacturers must submit labeling supplements within 30 days, adding warnings under sections 5.x and 6.2.1