Moderna flu shot data may support use in older adults, US FDA staff says

U.S. Food and Drug Administration staff reviewers said on Tuesday data demonstrating an immune response to Moderna's flu shot may support effectiveness in adults 65 years and older, sending its shares up 6%.

Moderna's shot, mFlusiva, also showed superior relative vaccine efficacy versus a standard-dose flu vaccine in adults aged 50 to 64, they said in briefing documents published ahead of a meeting of the regulator's independent advisers on Thursday.

The panel will vote on whether the benefits of mFlusiva outweigh the risks in adults 50 years and older.

FDA staff noted that Moderna's application for adults 65 and older mainly rests on immunogenicity data against a standard-dose vaccine rather than CDC-preferred high dose shots for older adults.

The assessment follows an unusually public clash between Moderna and the FDA, under the leadership of former commissioner Marty Makary. The regulator initially rejected the company's flu vaccine application over trial design concerns and later reversed course after the company agreed to amend its application.

Senior FDA officials had then said Moderna put patients at risk by not giving the preferred higher-dose flu vaccine to patients 65 and over as the control arm in its clinical trial.

Under the leadership of Makary and vaccine skeptic Health Secretary Robert F. Kennedy Jr., the FDA had shifted its approach to vaccine oversight. Kennedy and Makary have been particularly critical of mRNA vaccines.

The assessment highlights "a change in response to this specific application from a few months ago and let us hope more generally with respect to vaccines," said former FDA chief scientist Jesse Goodman.

Jefferies analyst Andrew Tsai said the assessment looks favorable, and that he expects $750 million of U.S. flu and COVID-flu combo vaccine sales by 2030.

FDA staff said Moderna's data had limitations that the committee should consider. They include the fact that the vaccine has only been studied during one influenza season and that because immunocompromised people and very frail older adults were excluded from trials, it is not clear that the vaccine is effective in this high-risk group.

Staff raised the idea that the group may respond differently to an mRNA-based vaccine, without providing further information.

Moderna has agreed to run an additional study and submit more data in adults 65 and older if they get approval for that age group.

Moderna is seeking a traditional approval of mFlusiva for adults 50 to 64 years old, and an accelerated approval for adults 65 and older.

If approved, mFlusiva would be the first mRNA-based seasonal flu vaccine in the U.S., with a decision expected by August 5.

Moderna did not immediately respond to a Reuters request for comment.

(Reporting by Christy Santhosh, Mariam Sunny in Bengaluru, Michael Erman in New York; Editing by Shilpi Majumdar and Devika Syamnath)

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This story was originally published June 16, 2026 at 12:40 PM.