Vinay Prasad, director of the FDA’s Center for Biologics Evaluation and Research (CBER), returned a refusal-to-file (RTF) for Moderna’s mRNA influenza candidate, sparking internal dissent and public pushback. Reporting cites internal complaints about Prasad’s conduct and disagreement among CBER reviewers over trial-control choices. Moderna and some FDA staff argued a review team was already assembled and had discussed the study design with CBER prior to submission. The episode centers on differences over the comparator arm in Moderna’s trial and the agency’s decision to halt intake rather than proceed with review. Sources include reporting in The Wall Street Journal, STAT News and statements from Moderna CEO Stéphane Bancel. The dispute may affect timelines for mRNA flu vaccine regulatory review and industry expectations for CBER adjudication. Clarification: An RTF (refusal-to-file) halts the formal review clock and requires sponsors to address foundational dossier deficiencies before a submission proceeds.