Core Insights - Moderna's shares fell approximately 10% in after-hours trading due to the FDA's refusal to file (RTF) letter regarding the biologics license application (BLA) for its investigational influenza vaccine, mRNA-1010 [1][8] - The FDA determined that the comparator used in the phase III study was not the best available standard of care, leading to the conclusion that the study was inadequate [2] Regulatory Context - The FDA's refusal was based on the use of a licensed standard-dose seasonal influenza vaccine as a comparator, which the agency deemed not optimal [2] - Prior communications from CBER indicated that a standard-dose vaccine would be acceptable, and no objections were raised before the study began [5][6] Market Performance - Over the past year, Moderna's shares have increased by 37.5%, outperforming the industry average rise of 18.7% [4] - Following the RTF letter, Moderna has requested a Type A meeting with the FDA to discuss the issues raised and to clarify the path forward for mRNA-1010 [9] Future Outlook - mRNA-1010 is under review in the European Union, Canada, and Australia, with plans for additional filings in 2026 [10] - The RTF letter is expected to delay the anticipated approval timeline for mRNA-1010 in the United States, which was initially expected in late 2026 [10]