FDA Staff Find Moderna's mFlusiva Data May Support Use In Older Adults; Advisory Panel To Vote June 18

FDA staff said data showing a strong immune response to Moderna's seasonal influenza vaccine candidate, mFlusiva, could support its effectiveness in adults aged 65 and older, while briefing documents also reported superior relative efficacy versus a standard-dose flu vaccine in adults 50–64.

What FDA Staff Found

Immunogenicity: Reviewers highlighted robust immune responses in the 65+ age group, which may support effectiveness despite the trial not using CDC-preferred high-dose comparators for that cohort.

Efficacy in 50–64: The briefing documents reported that mFlusiva demonstrated superior relative vaccine efficacy compared with a standard-dose influenza vaccine in adults 50–64 years old. Moderna's shares rose about 2% in morning trading after the documents were published.

Concerns and Limitations

FDA staff flagged several caveats: the application for adults 65 and older relies mainly on immunogenicity data rather than direct comparison with the higher-dose vaccines recommended by the U.S. Centers for Disease Control and Prevention for that age group. Other limitations include data from only a single influenza season, higher rates of short-term reactogenicity reported with mFlusiva, and the need for postmarket studies specifically in the 65+ population.

Regulatory Pathway and Timeline

The FDA's advisory committee will meet on June 18 to vote on whether the benefits of mFlusiva outweigh its risks for adults 50–64 and for those 65 and older. Moderna is seeking traditional (full) approval for adults 50–64 and an accelerated approval pathway for adults 65 and older. If approved, mFlusiva would become the first mRNA-based seasonal flu vaccine licensed in the United States. A final regulatory decision is expected by August 5.

Background

Earlier this year, under then-commissioner Marty Makary, the FDA rejected Moderna's initial application in February after senior officials raised concerns that the trial did not use the CDC-preferred higher-dose vaccine as the control for participants 65 and older. The agency later accepted an amended application after Moderna agreed to run a post-approval study in the older adult cohort.

Commercial Outlook and Commentary

Jefferies analyst Andrew Tsai described the staff assessment as favorable and projected roughly $750 million in U.S. sales for Moderna's flu and combined COVID-flu vaccines by 2030. Former FDA chief scientist Jesse Goodman said the staff assessment appeared reasonable and that the data support approval in both age groups. Moderna did not immediately respond to requests for comment.

Key Takeaway: FDA staff find the immunogenicity and efficacy data promising but want postmarket evidence and caution over comparisons to CDC-preferred high-dose vaccines for older adults.