A coalition of nearly all living past FDA commissioners published a sharp rebuke in the New England Journal of Medicine opposing plans by the FDA's biologics and vaccines chief to toughen vaccine update requirements. The former commissioners argue the proposed changes could disrupt longstanding regulatory practice. CBER director Vinay Prasad defended the policy shift in closed-door comments at an investor conference, saying the move modernizes vaccine update standards and that criticism stems from misleading narratives. The public dispute has intensified scrutiny of vaccine regulatory strategy and raised concerns across industry and public-health communities about the pace and scope of proposed changes.