Key Summary:
- FDA approves the first-ever mRNA flu vaccine.
- Green light comes despite the regulator's initial refusal to review it.
- Cleared for adults 50+, but 65s and over get only accelerated approval.
The first mRNA flu vaccine has been approved by the FDA for adults aged 50 and older, despite earlier setbacks in the approval process.
mFLUSIVA, developed by Moderna, secured a unanimous recommendation from the FDA’s Vaccines and Related Biological Products Advisory Committee, after the regulator initially refused to review the application back in February.
Why the FDA refused to review
Although the vaccine had delivered positive phase 3 trial results – the shot reduced confirmed flu cases by 26.6% compared with a standard-dose flu vaccine – the FDA issued a “refuse-to-file” letter over concerns with the trial design.
The letter, signed by Vinay Prasad – then Director of the FDA’s Center for Biologics Evaluation and Research, and since departed – said the trial was not “adequate and well-controlled” because the comparator did not reflect the “best-available standard of care” in the US.
At issue was Moderna’s choice to use a standard-dose flu vaccine as its benchmark, rather than testing the vaccine against the high-dose formulation typically given to adults over 65.
Today’s approval is the result of a U-turn that took place two weeks later, when the FDA reversed course and agreed to review the resubmitted application.
Stéphane Bancel, Chief Executive Officer, Moderna, welcomed the decision, saying, “flu remains a significant public health challenge, and mFLUSIVA provides an important new option for America’s seniors”.
What the approval means
The approval is a clear win for Moderna, but it isn’t a blanket one.
Adults aged 50 to 64 received full approval. Those 65 and older – the group at highest risk from flu – were granted only accelerated approval, with Moderna required to run a confirmatory trial in that population.
That study is expected to enrol up to 800,000 older adults across two flu seasons, with results not due until 2027 or 2028.
The additional trial aside, the company expects mFLUSIVA to be available in the US ahead of the 2026-2027 flu season, and has submitted it for review in the EU, Canada and Australia.
Featured image: wacomka on Adobe Stock
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