In a landmark decision for vaccine science, the US Food and Drug Administration (FDA) has approved the world's first messenger RNA (mRNA)-based seasonal influenza vaccine for older adults. Developed by Moderna, the vaccine, called mFlusiva, is authorised for adults aged 50 years and above, marking the first time mRNA technology, widely recognised for its role during the COVID-19 pandemic, has been approved for routine seasonal flu prevention.

The approval is being viewed as an important milestone because influenza viruses mutate frequently, requiring vaccines to be updated every year. Traditional flu vaccines are largely produced using egg- or cell-based manufacturing processes that take several months. Scientists believe mRNA technology could significantly shorten production timelines, allowing vaccines to be adapted more quickly if circulating influenza strains change unexpectedly.

The decision also comes at a time when seasonal influenza continues to cause substantial illness worldwide. According to the World Health Organization (WHO), annual influenza epidemics are estimated to cause 3-5 million cases of severe illness and up to 650,000 respiratory deaths globally each year.

What Has The FDA Approved?

The FDA approved Moderna's mFlusiva for adults aged 50 years and older.

The approval includes:

  • Traditional approval for adults aged 50-64 years
  • Accelerated approval for adults aged 65 years and older, with Moderna required to conduct additional studies to confirm long-term clinical benefits in this age group

This is the first seasonal influenza vaccine to use messenger RNA (mRNA) technology instead of the conventional egg-based manufacturing platform.

How Does An mRNA Flu Vaccine Work?

Unlike traditional influenza vaccines, which introduce weakened or inactivated viral proteins, an mRNA vaccine delivers genetic instructions that prompt the body's own cells to temporarily produce influenza proteins.

The immune system then recognises these proteins as foreign and generates protective antibodies and immune cells without causing influenza infection. This approach became widely known during the COVID-19 pandemic and offers several potential advantages, including faster vaccine design and manufacturing.

What Did The Clinical Trial Show?

The approval was supported by a Phase 3 clinical trial involving more than 40,000 adults aged 50 years and older.

According to Moderna, the vaccine:

  • Reduced laboratory-confirmed influenza cases by 26.6% compared with a standard licensed flu vaccine
  • Produced stronger immune responses than Sanofi's high-dose influenza vaccine in older adults, although additional studies are required to confirm whether this translates into improved clinical protection for people aged 65 years and above

The company is also conducting larger post-marketing studies to evaluate effectiveness in older adults over multiple influenza seasons.

Why Is This Approval Significant?

Seasonal influenza viruses constantly evolve, forcing scientists to update vaccine formulations each year. Traditional vaccine production often requires several months, leaving limited flexibility if circulating strains change after manufacturing begins.

Researchers believe mRNA technology could:

  • Speed up vaccine production
  • Enable faster strain updates
  • Improve the match between vaccines and circulating influenza viruses
  • Potentially strengthen protection in populations at highest risk of severe influenza, including older adults

The approval is also an important step for Moderna as it expands its vaccine portfolio beyond COVID-19 vaccines.

What Does This Mean For India?

The approval currently applies only to the United States and does not affect India's influenza vaccination programme. India already has several licensed seasonal influenza vaccines recommended for high-risk groups, including older adults, pregnant women, healthcare workers and people with chronic medical conditions, in accordance with national and international guidance.

Whether mRNA influenza vaccines become available in India will depend on future regulatory approvals by the relevant authorities.

The FDA's approval of the first mRNA-based seasonal influenza vaccine marks a significant advance in vaccine technology beyond COVID-19. While the immediate impact will be limited to eligible adults in the US, the decision could pave the way for faster, more adaptable influenza vaccines in the future. As influenza viruses continue to evolve every season, innovations that shorten vaccine development timelines may help improve protection for millions of people worldwide.



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