The first mRNA flu vaccine has been approved for adults aged 50 years and older, offering stronger protection against seasonal influenza than a standard flu shot.
- FDA approves the first mRNA seasonal flu vaccine for adults aged 50 years and older
- The vaccine showed 26.6% higher protection against laboratory-confirmed influenza
- Researchers say mRNA technology could improve future flu vaccines by adapting faster to changing viruses
Seasonal influenza continues to place a heavy burden on healthcare systems worldwide, especially among older adults who face a higher risk of severe illness, hospitalization, and death (1✔ ✔Trusted Source
BLA APPROVAL
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Although annual influenza vaccination remains the best way to reduce complications, the virus constantly changes, making it difficult for conventional vaccines to provide consistent protection every season.
The US Food and Drug Administration (FDA) has approved mFLUSIVA, the first mRNA-based seasonal influenza vaccine for adults aged 50 years and older.
The approval is supported by evidence from a large Phase 3 clinical trial published in the New England Journal of Medicine (NEJM), along with other immunology studies, which suggest that mRNA technology may generate broader and longer-lasting immune responses than conventional influenza vaccines (2✔ ✔Trusted Source
Efficacy and Safety of an mRNA Seasonal Influenza Vaccine in Adults
While additional post-marketing studies are still underway, the approval represents an important milestone in the development of next-generation influenza vaccines.
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Why Is the First mRNA Flu Vaccine Considered a Major Breakthrough?
mFLUSIVA is the first mRNA vaccine approved specifically for the prevention of seasonal influenza in adults aged 50 years and older.
Unlike conventional influenza vaccines that are produced using egg- or cell-based manufacturing methods, the new vaccine uses messenger RNA (mRNA) technology to instruct the body’s cells to temporarily produce influenza proteins, allowing the immune system to recognize and fight the virus without exposure to the virus itself.
Researchers believe this platform offers several potential advantages. Because influenza viruses undergo frequent genetic changes, mRNA vaccines can be updated more rapidly to match newly circulating strains.
According to researchers in Nature Immunology, this technology also appears capable of generating broader antibody responses, potentially improving protection against influenza viruses that continue to evolve after the annual vaccine has been developed (2✔ ✔Trusted Source
Efficacy and Safety of an mRNA Seasonal Influenza Vaccine in Adults
The FDA has also granted accelerated approval for adults aged 65 years and older, recognizing the urgent need for better influenza protection in this high-risk group while requiring Moderna to complete confirmatory clinical studies to verify long-term clinical benefit.
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Did the New Vaccine Perform Better Than Standard Flu Vaccines?
The approval rests mainly on the Phase 3 FLUENT trial, which studied over 40,700 adults aged 50 and older.
People who got the new mRNA flu vaccine caught confirmed flu less often than those who got a standard flu shot, about 26.6% better protection.
Side effects like soreness, tiredness, and headache were a bit more common with the mRNA shot, but serious problems were rare and about equal in both groups. In simple terms: better protection, no extra safety risk.
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How the New mRNA Flu Vaccine Compares with a Standard Flu Vaccine
| Parameter | New mRNA Flu Vaccine (mFLUSIVA) | Standard Flu Vaccine |
|---|---|---|
| Vaccine technology | mRNA-based (same platform used in COVID-19 vaccines) | Conventional, grown in eggs or cells |
| Study population | 40,700+ adults aged 50 years and above | Same trial, comparator group |
| Vaccine efficacy | 26.6% higher relative efficacy against lab-confirmed flu | Reference (baseline) vaccine |
| Common side effects | Injection-site pain, fatigue, headache, muscle aches | Similar side effects, but less frequent |
| Duration of mild side effects | Typically 1 to 3 days | Typically 1 to 3 days |
| Serious adverse events | Rare | Rare, similar rate |
| Overall safety profile | No new safety concerns identified | Well-established, long-standing safety record |
| Key takeaway | Stronger protection with a comparable safety profile | Standard, reliable protection |
Why Could mRNA Technology Offer Broader and Longer-Lasting Protection?
Beyond the positive Phase 3 results, earlier studies suggest that mRNA technology may produce a stronger and more durable immune response than conventional influenza vaccines.
According to Nature Immunology, the investigational mRNA influenza vaccine was associated with:
- Higher antibody levels against influenza viruses.
- More memory B cells, which help the body respond quickly to future infections.
- Broader antibody responses capable of recognizing a wider range of influenza variants.
- Persistent germinal center activity for up to 26 weeks in some participants, allowing antibodies to continue maturing and diversify over time.
Supporting these findings, researchers in npj Vaccines reported that the investigational vaccine (4✔ ✔Trusted Source
An mRNA influenza vaccine induces immunity comparable to an adjuvanted vaccine in a randomized trial
):
- Generated durable antibody responses lasting up to one year.
- Maintained strong memory B-cell and T-cell responses.
- Demonstrated an acceptable safety profile in early clinical studies.
Together, these findings suggest that mRNA technology could provide broader and longer-lasting protection against influenza while supporting the development of next-generation flu vaccines.
How Could mRNA Technology Improve Future Flu Vaccines?
Influenza viruses change constantly, making it difficult for seasonal vaccines to provide consistent protection every year.
mRNA technology may overcome some of the challenges by generating broader, longer-lasting immune responses and adapting more quickly to circulating virus strains. Key findings from both studies are summarized below.
Potential Advantages of mRNA Technology for Influenza Vaccines
| Current Challenge | How mRNA Technology May Help |
|---|---|
| Influenza viruses evolve rapidly | Vaccine can be updated more quickly to match circulating strains. |
| Limited protection against new variants | Produced broader antibody responses capable of recognizing diverse influenza strains. |
| Immunity may weaken over time | Generated durable antibody, memory B-cell, and T-cell responses. |
| Antibodies lose effectiveness as viruses mutate | Stimulated persistent germinal center activity for up to 26 weeks, allowing antibodies to continue maturing and diversify. |
| Need for better long-term protection | Expanded antibody diversity may improve protection against evolving influenza viruses and support future universal vaccine development. |
Why Are Better Flu Vaccines Still Needed?
Seasonal influenza vaccines remain the best way to reduce serious illness and hospitalization.
However, according to JAMA Network Open, influenza viruses continue to evolve, making it difficult for vaccines to provide consistent protection every year.
The 2025–2026 influenza season highlighted several ongoing challenges (5✔ ✔Trusted Source
Influenza Activity and Estimated Vaccine Effectiveness During the 2025-2026 Influenza Season
- Influenza A(H3N2) viruses caused most infections during the season.
- Seasonal flu vaccines continued to reduce emergency department visits and hospitalizations, confirming their important public health role.
- Vaccine effectiveness declined when circulating viruses drifted away from the strains included in the vaccine, reducing protection in some people.
Researchers suggest that mRNA technology could help overcome this challenge because vaccine strains can be updated more rapidly than conventional influenza vaccines, potentially improving the match with circulating viruses.
Frequently Asked Questions
Q: What is mFLUSIVA and what type of Flu Vaccine is it?
A: mFLUSIVA is an FDA-approved mRNA influenza vaccine for adults aged 50 years and older. It uses messenger RNA (mRNA) technology to trigger an immune response against seasonal influenza.
Q: How does the mFLUSIVA mRNA Flu Vaccine Work?
A: The mFLUSIVA mRNA flu vaccine uses messenger RNA to instruct cells to produce influenza proteins that stimulate an immune response. Unlike traditional flu vaccines, it does not use the influenza virus itself to generate immunity.
Q: How effective is the mFLUSIVA mRNA Influenza Vaccine?
A: In a Phase 3 clinical trial involving more than 40,700 adults, mFLUSIVA demonstrated 26.6% higher protection against laboratory-confirmed influenza compared with a standard-dose flu vaccine.
Q: Is mFLUSIVA Safe for Adults?
A: The Phase 3 clinical trial identified no new safety concerns with mFLUSIVA. Common side effects included injection-site pain and fatigue, while serious adverse events were uncommon.
Q: Who is Eligible to Receive the mFLUSIVA Flu Vaccine?
A: mFLUSIVA is FDA-approved for adults aged 50 years and older. The vaccine received accelerated approval for adults aged 65 years and above, subject to the applicable regulatory requirements.
Q: Why are mRNA Influenza Vaccines Needed?
A: Seasonal influenza viruses continually evolve, which can reduce the effectiveness of conventional flu vaccines when circulating strains differ from vaccine strains. mRNA influenza vaccines could offer a flexible approach to developing and updating vaccines against changing flu viruses.
Q: What makes mFLUSIVA Different from Traditional Flu Vaccines?
A: The key difference is the vaccine technology. mFLUSIVA uses mRNA to stimulate an immune response, while conventional influenza vaccines typically use inactivated or otherwise prepared viral components. This makes mFLUSIVA part of a newer generation of influenza vaccine technology.
References:
- BLA APPROVAL – (https://www.fda.gov/media/194121/download?attachment)
- Efficacy and Safety of an mRNA Seasonal Influenza Vaccine in Adults – (https://www.nejm.org/doi/full/10.1056/NEJMoa2516491)
- mRNA-based influenza vaccine expands the B cell response breadth in humans – (https://www.nature.com/articles/s41590-026-02569-5)
- An mRNA influenza vaccine induces immunity comparable to an adjuvanted vaccine in a randomized trial – (https://www.nature.com/articles/s41541-026-01370-7)
- Influenza Activity and Estimated Vaccine Effectiveness During the 2025-2026 Influenza Season – (https://jamanetwork.com/journals/jamanetworkopen/fullarticle/2850461)
Source-Medindia