FDA experts endorse Moderna's mRNA seasonal flu shot

Moderna has moved a little closer to US approval of its new mRNA-based seasonal influenza vaccine, mFlusiva, after an FDA expert panel unanimously concluded it was safe and effective.

The Vaccines and Related Biological Products Advisory Committee (VRBPAC) voted nine to zero in favour of mFlusiva (mRNA-1010) for two age ranges – 50 to 64-year-olds and people aged 65 and over – setting up what should be a positive approval decision by the FDA, which is due by 5th August.

Rewind to February of this year, and the prospects for mFlusiva were looking decidedly shaky, after the FDA refused to accept Moderna's marketing application for the vaccine, one of three the company is hoping to roll out between now and the end of 2028 in an acceleration of its commercial presence.

Accused of diverging from an already-agreed regulatory pathway for mFlusiva – and amid reports that the then director of the FDA's Center for Biologics Evaluation and Research (CBER), Vinay Prasad, had overruled the agency's reviewers – the agency relented two weeks later and allowed the review to go ahead.

The strong endorsement of mFlusiva's safety and efficacy offers some relief to Moderna and other companies working on mRNA technologies, which have come under attack by the Trump administration under vaccine sceptic HHS Secretary Robert F Kennedy Jr, who has questioned the safety of mRNA vaccines and withdrew $500 million in federal contracts to develop them last year.

mFlusiva is the first new vaccine to be considered by the VRBPAC since 2023, and the positive outcome is raising the hope of a return to a more conventional approach to vaccine regulation following the departures of Prasad and FDA Commissioner Marty Makary.

The FDA's briefing document on mFlusiva pointed to some gaps in the efficacy data submitted by the company – noting that trials were conducted over a single flu season and that there was little data in older, frailer patients – but said it had found no worrying safety signals in Moderna's data.

A big advantage of mRNA vaccines is that they can be produced more quickly than conventional vaccines, which means developers can wait longer to see which flu strains are likely to be circulating in the next season. If approved, mFlusiva will be the first flu jab to use the technology in the US, although it is well-established for other diseases like COVID-19.

"We appreciate the thoughtful review by the members of VRBPAC and their recognition of the clinical evidence supporting mRNA-1010," said Moderna's chief executive, Stéphane Bancel, who noted that influenza continues to cause substantial illness and hospitalisations among older adults each year.

During the 2025-2026 season, for example, the CDC recorded around 32 million cases, 390,000 hospitalisations, and 24,000 deaths from flu.

"We believe mRNA-1010 has the potential to provide an important new option for seasonal flu prevention and further demonstrate the versatility of our mRNA platform," added Bancel.

The vaccine has also been submitted for approval in Europe, Canada, and Australia, with additional filings planned between now and the end of the year, according to Moderna.