Twelve former FDA commissioners published a critique in the New England Journal of Medicine opposing proposed changes to vaccine regulation advanced by Vinay Prasad, director of CBER. The ex-commissioners warned that Prasad’s plan to demand larger, longer studies for vaccine updates could undermine established regulatory practice. Prasad defended his proposals at a closed-door investor conference, saying media narratives have mischaracterized his intentions and framing the changes as modernization rather than wholesale reversal. The dispute—covered in NEJM and STAT reporting—escalates internal and external tensions at the agency and highlights disagreement among senior public‑health figures about standards for vaccine evidence and updates.