Last updated: October 16, 2026

Medical disclaimer: This article is for general information and is not medical advice. Talk to your doctor or pharmacist about which flu vaccine is right for you.

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What Is the mRNA Flu Vaccine?

The mRNA flu vaccine is a new type of seasonal flu shot. Instead of delivering a weakened or killed virus (or a purified protein), it delivers a short piece of genetic instructions (messenger RNA) that tells your own cells to make one harmless flu protein, the hemagglutinin “spike” on the virus surface. Your immune system then learns to recognize it. [6]

The vaccine itself contains no flu virus, so it cannot give you the flu. [5] It also contains no egg protein and no preservatives. [4]

The first approved product is mFLUSIVA, made by Moderna. It is a trivalent vaccine, meaning it protects against three flu strains: two influenza A strains and one B/Victoria strain. [16] It is given as a single 0.38 mL injection into the upper arm muscle once per flu season. [4]

Is mFLUSIVA the “First mRNA Flu Vaccine in the World”?

Not quite, and this is a detail most articles blur.

  • In the United States, mFLUSIVA is the first mRNA-based flu vaccine the FDA has approved. [1]
  • In Europe, the European Commission authorized Moderna’s mCOMBRIAX on April 21, 2026. It is a combined flu + COVID-19 mRNA vaccine for adults 50+, and it contains the same flu mRNA component. [21][22]

So a flu-containing mRNA vaccine reached the market in Europe first. The stand-alone mRNA flu shot arrived in the U.S. in August 2026.

Who Can Get the mRNA Flu Vaccine?

Adults 50 years and older. That is the only approved group. [1]

  • Ages 50-64: full FDA approval, based on a large efficacy trial. [3]
  • Ages 65+: accelerated approval, based on immune-response (antibody) data. Moderna must run a follow-up trial to confirm real clinical benefit. [3][4]
  • Under 50: not approved. A pharmacist quoted by NBC News put it bluntly: if you haven’t had your 50th birthday, this vaccine isn’t for you. [13] Approval for younger adults would need separate trials. [6]
  • Pregnancy and breastfeeding: data are insufficient to say anything about risk, and it isn’t known whether the vaccine passes into breast milk. [5]

How Well Does It Work? The Numbers Explained

The headline result

In the phase 3 trial published in the New England Journal of Medicine, adults 50+ received either mFLUSIVA or a licensed standard-dose flu vaccine. Lab-confirmed flu-like illness occurred in:

  • 2.0% of mFLUSIVA recipients (411 of 20,179)
  • 2.8% of standard-dose recipients (557 of 20,124)

That works out to a relative vaccine efficacy of 26.6% (95% confidence interval 16.7% to 35.4%). [2]

What “26.6%” actually means (and doesn’t)

This is where many articles go wrong. 26.6% is not “the vaccine is 26.6% effective.” It means mFLUSIVA recipients had about 27% fewer flu illnesses than people who got a standard-dose shot.

In absolute terms, the gap was about 0.7 percentage points (roughly 2.04% vs 2.77%). By my own back-of-the-envelope calculation from the published case counts, that is about one fewer case of flu-like illness for every ~135-140 people vaccinated with mFLUSIVA instead of a standard-dose shot, over a median follow-up of about six months. That is a real benefit, but a more modest-sounding one than the headline suggests. (Absolute benefit grows in a bad flu season and in older, higher-risk groups.)

By strain and age

  • The relative efficacy was reported as 29.6% against A/H1N1, 22.2% against A/H3N2 and 29.1% against B/Victoria. [19]
  • In adults 65+, relative efficacy was 27.4% (95% CI 12.1% to 40.0%). [2][17]
  • When researchers counted broader outcomes (urgent care, emergency visits, hospitalizations), one report put the relative efficacy at 47.9%. [11] Treat that figure as secondary evidence, since it is a different endpoint from the main trial result.

Beyond the trial: a 2026 “matching” advantage

All three virus components in the 2026-27 flu vaccines were changed from last season. [15] mRNA’s biggest theoretical advantage is speed. Because the genetic “script” can be rewritten quickly, without growing virus in eggs, Johns Hopkins vaccine researcher Anna Durbin says it is “without a doubt” the fastest way to update a vaccine, and it could one day allow shots that match circulating strains better. [6] That benefit is not yet proven in real-world seasons.

mRNA Flu Vaccine vs. High-Dose and Other Flu Shots

This is the most important section for anyone 65 or older.

The CDC recommends higher-dose, recombinant or adjuvanted flu vaccines for adults 65+. [16] The mFLUSIVA efficacy trial compared the vaccine against a standard-dose shot, not one of these “enhanced” vaccines. [20]

What we do know about the high-dose comparison:

  • A separate trial of ~3,000 adults 65+ compared antibody responses to a high-dose vaccine. mFLUSIVA produced higher antibody levels (ratios of roughly 1.2 to 1.3). [18][27] This was the basis for the accelerated approval in the 65+ group. [1]
  • But antibodies are a stand-in, not proof of fewer infections. A modeling study estimated mRNA-1010 could be about 12.4% more effective than high-dose vaccine, with a wide uncertainty range (95% CI 3.4% to 21.3%). [17] That is a projection from lab data, in a preprint, and authors of the analysis note that no direct head-to-head efficacy study against enhanced vaccines exists. [18]
  • An independent expert quoted by Medical News Today called the approval important but cautioned against assuming mRNA is the best option for everyone over 50, and said she’d want another season or two of real-world evidence before calling it superior to the established enhanced vaccines. [12]

Bottom line: For ages 50-64, where there is no “preferred” enhanced shot, the efficacy data are strong. For 65+, the data are promising but indirect. Ask your clinician; any of the options is better than going unvaccinated.

Side Effects of the mRNA Flu Vaccine

In the large trial, short-term reactions were more common with mFLUSIVA than with the standard-dose shot: [2]

ReactionmFLUSIVAStandard-dose
Injection-site pain65.8%29.8%
Fatigue45.1%20.3%
Headache37.8%(lower)

Most reactions were mild to moderate and went away on their own. [29]

Serious adverse events were reported in 2.2% of mFLUSIVA recipients vs 1.9% of the comparator group, and only a handful were judged vaccine-related by investigators (3 vs 2). [2]

Hopkins’s Durbin notes that the safety profile should resemble mRNA COVID vaccines because the platform is the same, with only the protein produced being different. [6] The 2026-27 season will provide the first real-world data in groups usually excluded from trials, such as transplant recipients and people with severe immune problems. [6]

Who should not get it, or should ask first

  • Do not get it if you’ve had a severe allergic reaction (anaphylaxis) to mFLUSIVA or any of its ingredients. This is the only listed contraindication. [5]
  • Talk to your provider first if you had Guillain-Barre syndrome within 6 weeks of a previous flu shot, have a weakened immune system (the response may be lower), or tend to faint with injections. [5]

How Much Does the mRNA Flu Vaccine Cost?

  • CMS lists a price of about $171 per dose without insurance, according to NBC News. [13]
  • Discount-coupon sites showed about $155 (GoodRx) to $160 (SingleCare), with list or retail prices up to roughly $183-$216; another site started at about $190. [14] Prices change often.

Insurance coverage typically follows FDA approval, but plans differ. [6] Before you go, call your pharmacy and your insurer, and ask whether you will be billed under your medical or pharmacy benefit. Traditional flu shots remain widely available and are generally cheaper. [6]

Where Can You Get It?

Moderna began shipping doses across the U.S. in September 2026, and CVS reported having it in stock, with Walgreens expecting shipments, according to NBC News. [13] Availability depends on your local pharmacy’s stock. [6] Moderna offers a locator tool at products.modernatx.com/finder. [14]

Has the CDC Recommended It? (An Overlooked Detail)

This is a gap most guides skip. The CDC’s interim clinical considerations for 2026-27, published September 1, 2026, were silent on mFLUSIVA, per Immunize.org. [15] Federal court orders have also kept earlier CDC flu recommendations in effect after ACIP’s membership changed in 2025. [15]

In practice, that means the vaccine is FDA-approved and on shelves, but not yet singled out in the CDC’s preferred-vaccine list for older adults. Other medical groups have started to weigh in; for example, a National Council on Aging summary says the AAFP’s 2026-27 guidance counts mRNA vaccines among the enhanced options for 65+. [28] Check the CDC’s latest flu page and ask your clinician, because guidance may update during the season.

The Behind-the-Scenes Story: Why Approval Almost Didn’t Happen

  • February 2026: The FDA’s vaccine center issued a rare refusal-to-file letter, declining even to review Moderna’s application. The stated reason: Moderna compared its vaccine with a standard-dose shot rather than a high-dose one for older adults. [7][8]
  • Within about a week, the FDA reversed course after a meeting with Moderna, and accepted the filing with a split plan: full approval for ages 50-64, accelerated approval for 65+. [10]
  • June 18, 2026: An FDA advisory committee voted 9-0 that benefits outweigh risks, for both 50-64 and 65+. [11]
  • August 5, 2026: FDA approval. [1]

Supporters, including a CIDRAP commentary, argued the refusal had a “flimsy rationale,” pointing out that Moderna had also submitted high-dose comparison data. [9] The episode explains why the 65+ approval is “accelerated” and why Moderna owes a confirmatory study. [3][4]

mRNA Flu Vaccine vs. mRNA COVID Vaccine: Same Technology, Different Job

Both use mRNA delivered in a lipid nanoparticle, but they instruct your cells to make different proteins. [6] Durbin says COVID put the manufacturing supply chain through a real-world stress test, which helps scale-up for flu. [6]

What’s Next: Combination Flu + COVID Shots

  • Moderna mCOMBRIAX (flu + COVID, mRNA) is authorized in the EU for adults 50+. [21] In the U.S., Moderna had to withdraw and refile its application because regulators wanted flu efficacy data, and it was awaiting FDA guidance on refiling as of its latest annual report. [23]
  • Pfizer/BioNTech (mRNA) and Sanofi/Novavax (protein-based) are also developing flu-COVID combinations. [25][24]

Common Myths About mRNA Flu Shots

  • “It can give you the flu.” No. It has no virus in it. [5]
  • “It changes your DNA.” mRNA delivers temporary instructions that cells read and then break down; it is not designed to enter the cell nucleus or alter your genes. (This is established mRNA biology; see your doctor for more.)
  • “It’s brand-new and untested.” The flu vaccine’s safety has been studied in roughly 70,000 people across trials, per Hopkins. [6] That said, long-term and real-world data for this specific vaccine are still being collected.
  • “It replaces regular flu shots.” No. Traditional vaccines remain widely available this season. [6]

Frequently Asked Questions

Is the mRNA flu vaccine safe? A unanimous FDA advisory vote found benefits outweigh risks for adults 50+. [11] Short-term reactions are more common than with standard shots; serious events were rare and similar between groups. [2]

Is the mRNA flu vaccine better than the regular flu shot? Compared with a standard-dose shot, it prevented about 27% more flu illness in trials. [2] Against high-dose vaccines for 65+, the evidence is indirect so far. [18]

Can I get the mRNA flu shot if I am 45? No. It is approved only for 50+. [1]

Is it a one-dose or two-dose vaccine? One 0.38 mL dose per flu season. [4]

Does it contain egg? No. [4]

How long does protection last? The trial followed participants for a median of about six months. [2] Annual vaccination is still needed because strains change.

Can I get a flu shot and a COVID shot at the same time? Ask your provider; combined and co-administration guidance depends on the specific products and updates over time.

Is the mRNA flu vaccine available outside the U.S.? As of the approval announcement, it was under review in the EU, Canada and Australia, with more submissions planned. [1] Check your national regulator for the current status.

When should I get vaccinated? Ideally before the end of October, though later vaccination still helps because flu season usually peaks between December and February. [16]

The Bottom Line

mFLUSIVA is a genuine milestone: the first mRNA flu vaccine cleared by the FDA, with strong results against standard-dose shots in adults 50+. It is not yet proven to beat the high-dose and adjuvanted vaccines recommended for people 65+, side effects are more noticeable, and this will be the season that shows how it performs in the real world. The best flu vaccine is still the one you actually get, so talk to your pharmacist or doctor about your options.

References

  1. Moderna. FDA Approves mFLUSIVA (influenza vaccine, mRNA) for the Prevention of Seasonal Influenza (press release, Aug 5, 2026). https://www.drugs.com/newdrugs/fda-approves-mflusiva-influenza-vaccine-mrna-prevention-seasonal-influenza-6855.html
  2. Efficacy and Safety of an mRNA Seasonal Influenza Vaccine in Adults. New England Journal of Medicine. https://www.nejm.org/doi/full/10.1056/NEJMoa2516491
  3. HCPLive. mFLUSIVA Receives FDA Approval for Influenza in Adults 50 and Older. https://www.hcplive.com/view/mflusiva-fda-approval-influenza-adults-50-older
  4. Drugs.com. mFlusiva (prescribing details and FAQs). https://www.drugs.com/mflusiva.html
  5. U.S. FDA / DailyMed. MFLUSIVA Prescribing Information and Information for Recipients. https://dailymed.nlm.nih.gov/dailymed/drugInfo.cfm?setid=3dd1c6d2-b054-4803-bb21-460b1b090d4c and https://www.fda.gov/media/194126/download
  6. Winny, A. New mRNA Flu Vaccine Makes This Flu Season “One to Watch.” The Uptake, Johns Hopkins Bloomberg School of Public Health, Aug 25, 2026 (interview with Anna Durbin, MD).
  7. CNN. FDA refuses to review Moderna’s application for mRNA flu vaccine, company says (Feb 10, 2026). https://www.cnn.com/2026/02/10/health/fda-moderna-mrna-flu-vaccine
  8. BioPharma Dive. FDA refuses to review Moderna’s mRNA flu vaccine. https://www.biopharmadive.com/news/moderna-fda-influenza-mrna-refuse-to-file/811909/
  9. CIDRAP. Op-Ed: The FDA refused to review a flu vaccine, contrary to evidence. Now the agency reversed itself. https://www.cidrap.umn.edu/influenza-vaccines/cidrap-op-ed-fda-refused-review-flu-vaccine-contrary-evidence-now-agency
  10. Drug Topics. FDA Reverses Stance, Initiates Formal Review for Moderna Flu Vaccine. https://www.drugtopics.com/view/fda-reverses-stance-initiates-formal-review-for-moderna-flu-vaccine
  11. BioPharma International. FDA Advisory Panel Votes 9-0 in Favor of Moderna’s mRNA Flu Vaccine. https://www.biopharminternational.com/view/fda-advisory-panel-votes-9-0-in-favor-of-moderna-s-mrna-flu-vaccine-setting-stage-for-august-decision
  12. Medical News Today. New flu vaccine: Moderna’s mRNA vaccine approved by FDA. https://www.medicalnewstoday.com/articles/modernas-mrna-flu-vaccine-approved-fda-when-available
  13. NBC News. mFlusiva, the first mRNA flu shot, is now available. Here’s what to know (Sept 18, 2026). https://www.nbcnews.com/health/health-news/mrna-flu-vaccine-moderna-mflusiva-explained-rcna598524
  14. GoodRx and SingleCare mFlusiva price pages (prices vary, checked Oct 2026). https://www.goodrx.com/mflusiva and https://www.singlecare.com/prescription/mflusiva
  15. Immunize.org. Ask the Experts: Influenza (last reviewed Oct 11, 2026). https://www.immunize.org/ask-experts/topic/influenza/
  16. Johns Hopkins Medicine. 2026-27 Flu, COVID-19 and RSV Vaccine Recommendations. https://www.hopkinsmedicine.org/health/wellness-and-prevention/2026-2027-flu-covid19-rsv-vaccine-recommendations
  17. medRxiv preprint. The Potential Public Health Benefit of mRNA-1010 for Adults 65+. https://www.medrxiv.org/content/10.64898/2026.09.20.26363308v1.full.pdf
  18. Estimating the Relative Vaccine Efficacy of mRNA-1010 to High-Dose Influenza Vaccine in Adults ≥65 Years Using a Correlate of Protection Framework. Vaccines (MDPI). https://doi.org/10.3390/vaccines14090750
  19. Contagion Live. Moderna’s mRNA-1010 Shows Efficacy in Phase 3 Seasonal Flu Vaccine Trial. https://www.contagionlive.com/view/moderna-s-mrna-1010-shows-efficacy-in-phase-3-seasonal-flu-vaccine-trial
  20. Applied Clinical Trials. Phase 3 Trial Finds Moderna’s mRNA-1010 Influenza Vaccine Outperformed Standard-Dose Vaccines. https://www.appliedclinicaltrialsonline.com/view/moderna-mrna-1010-influenza-vaccine-
  21. BioSpace / Moderna. European Commission Marketing Authorization for mCOMBRIAX. https://www.biospace.com/press-releases/moderna-receives-european-commission-marketing-authorization-for-mcombriax-modernas-mrna-combination-vaccine-against-influenza-and-covid-19
  22. CIDRAP Influenza Vaccines R&D Roadmap. Previous Landscape Updates. https://ivr.cidrap.umn.edu/previous-landscape-updates
  23. Moderna, Inc. Form 10-K for FY2025 (SEC). https://www.sec.gov/Archives/edgar/data/1682852/000168285226000033/mrna-20251231.htm
  24. Contract Pharma. Sanofi’s Combo Vaccine for Flu and COVID-19 Gets FDA Fast Track. https://www.contractpharma.com/breaking-news/sanofis-combo-vaccine-for-flu-and-covid-19-gets-fda-fast-track/
  25. pharmaphorum. Moderna says COVID/flu shot clears phase 3 hurdle (mentions Pfizer/BioNTech and Sanofi/Novavax programs). https://pharmaphorum.com/news/moderna-says-covidflu-shot-clears-phase-3-hurdle
  26. NPR. FDA approves Moderna flu shot made with mRNA (Aug 6, 2026). https://www.npr.org/2026/08/06/nx-s1-5923342/moderna-mrna-flu-vaccine
  27. U.S. FDA. Briefing document on mRNA-1010 (Study P303 Part C vs high-dose comparator). https://www.fda.gov/media/193130/download
  28. National Council on Aging. Flu Season 2026-2027: What Older Adults Need to Know. https://www.ncoa.org/article/what-older-adults-need-to-know-during-flu-season/
  29. ReachMD. mRNA-1010 Outperforms Standard Flu Vaccine in Phase 3 Trial. https://reachmd.com/news/mrna-1010-outperforms-standard-flu-vaccine-in-phase-3-trial/2488438/

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