The FDA declined to review Moderna’s mRNA flu vaccine application, a move that has clouded the company’s cash‑flow guidance and reignited debate over regulatory expectations for next‑generation vaccines. Industry sources and news outlets reported the agency’s refusal as a surprise to companies planning mRNA seasonal products. Separately, the development has sparked a broader policy confrontation as pediatricians and other stakeholders press HHS and regulators on vaccine standards and access. The combination of regulatory ambiguity and high commercial stakes is prompting investors and developers to reassess timelines and trial designs for mRNA seasonal programs.