The FDA issued a refuse‑to‑file for Moderna’s next‑generation mRNA influenza vaccine, halting the agency review the company expected and prompting scrutiny of trial design and comparator choice. Moderna submitted supporting analyses from prior studies, but the agency declined to accept the file, an action that surprised company leadership. The setback comes amid a broader reshaping of Moderna’s R&D footprint: the company cut research spending roughly 31% in 2025 and said it wound down several late‑stage respiratory programs. Moderna has signaled a strategic pivot toward oncology and other prioritized assets while evaluating next steps for its flu program and regulatory engagement. The refusal-to-file raises questions about regulatory expectations for comparator arms and could influence industry planning for respiratory vaccine programs.