The United States Food and Drug Administration (FDA) has approved the first-ever mRNA-based influenza vaccine, marking a significant milestone in the evolution of vaccine technology. The vaccine, called mFLUSIVA and developed by the American biotechnology company Moderna, has been authorised for adults aged 50 and older and will be available from the 2026–2027 respiratory virus season. The decision extends the mRNA platform — first widely deployed during the Covid-19 pandemic — into routine seasonal immunisation.

Approval was based on results from a large phase 3 clinical trial involving nearly 41,000 adults aged 50 and older across 11 countries, as well as a separate study of close to 3,000 adults aged 65 and older in the United States. The vaccine was found to offer greater protection against influenza compared to standard flu shots. "mFLUSIVA provides an important new option for America's seniors," said Moderna Chief Executive Stéphane Bancel, describing the decision as a reflection of "the ongoing potential of our mRNA platform to help address important public health challenges through continued scientific innovation."

mRNA vaccines work by delivering genetic instructions — in the form of messenger RNA encased in tiny fat-based particles called lipid nanoparticles — that direct the body's own cells to produce a harmless protein resembling part of a pathogen. The immune system then learns to recognise and respond to that protein. A key scientific breakthrough underpinning modern mRNA vaccines, recognised with the 2023 Nobel Prize in Physiology or Medicine, involved chemically modifying one of mRNA's building blocks to prevent unwanted inflammatory responses, a technique used in both the Moderna and Pfizer-BioNTech Covid-19 vaccines.

One of the defining advantages of mRNA technology is its programmability. Because different mRNA drugs produced by the same manufacturing methods behave similarly in the body — reaching the same tissues, triggering comparable immune responses, and degrading at predictable rates — development costs and risks are substantially lower than for traditional vaccines. This predictability has fuelled interest in applying mRNA beyond vaccines, including to gene-editing therapies for rare genetic diseases such as hereditary transthyretin amyloidosis, where short-lived mRNA molecules carrying CRISPR-Cas9 instructions could potentially offer a one-time treatment.

Regulatory progress varies by region. In Europe, where the vaccine is still under review by the European Medicines Agency (EMA), a different combined mRNA product — mCombriax, which protects against both Covid-19 and influenza — was approved earlier this year for adults aged 50 and over, though it has not been cleared in the United States. Researchers caution that while the momentum behind mRNA technology is strong, challenges remain, particularly for treatments requiring proteins to persist in the body over long periods or those demanding minimal immune activation. Further advances in mRNA stability and manufacturing purity will be needed before the technology can fully realise its potential beyond the vaccine field.