Flu season is starting, and this year there’s a new option on the shelf. FDA approval for mFlusiva was granted on August 5, 2026, making it the first mRNA-based influenza vaccine approved. It is approved for use in persons 50 years of age and older. Drugs.comFDA

For practices that already handle mRNA COVID-19 and RSV vaccines, parts of this will feel familiar. Other parts are different, especially around storage and handling. Read on to learn everything your team needs to know before vaccination begins.

What Is mFlusiva? Moderna’s mRNA Flu Vaccine Explained

mFlusiva is Moderna’s influenza vaccine, and FDA approval was granted on August 5, 2026, making it the first mRNA-based influenza vaccine approved. It is indicated for active immunization against influenza disease caused by the influenza A subtypes and type B represented in the vaccine.

Traditional flu vaccines introduce inactivated virus or purified viral proteins. mFlusiva works differently. It delivers mRNA instructions, encapsulated in lipid nanoparticles, that prompt the patient’s own cells to temporarily produce hemagglutinin, the influenza surface protein. The immune system recognizes that protein and builds protection, without any exposure to live or killed virus.

Like this season’s traditional flu vaccines, mFlusiva is trivalent, targeting two influenza A strains and one influenza B strain. It contains no egg protein, antibiotics, or preservatives, and cells are not used in its manufacturing.

mFlusiva Indications and FDA Approval Status by Age Group

mFlusiva is approved for adults 50 and older, but the approval basis differs by age:

Adults 50 to 64: Full FDA approval.

Adults 65 and older: Approved under the FDA’s accelerated approval pathway based on immune responses. Continued approval for this age group may depend on results from ongoing confirmatory studies.

mFlusiva Efficacy: FLUENT Phase 3 Trial Results

Approval was based on the phase 3 FLUENT trial, a randomized, observer-blind study comparing mFlusiva with a licensed standard-dose flu vaccine in adults 50 and older. The trial enrolled 40,703 adults, about half of whom received mFlusiva.

mFlusiva met all primary endpoints, including noninferiority and superiority, with approximately 26.6% relative vaccine efficacy against influenza-like illness caused by influenza A or B. In a separate study against Fluzone High-Dose, mFlusiva produced a stronger immune response in adults 65 and older.

The mRNA platform also offers a manufacturing advantage. Because mRNA vaccines can be updated in weeks, there is potential to shorten the gap between strain selection and distribution in future seasons.

mFlusiva Side Effects and Safety Profile

Reactogenicity is higher than with standard-dose flu vaccines, so setting expectations matters. The most common side effects in the FLUENT trial were injection-site pain (65.8%), fatigue (45.1%), and headache (37.8%). Most were mild to moderate and transient, and generally went away in about 2 days.

mFlusiva Storage and Handling Requirements: Temperature, Light, and the 12-Hour Rule

Proper cold chain management is where mFlusiva doses are most likely to be protected or lost.

Refrigerated storage: Store at 2°C to 8°C (36°F to 46°F). Do not freeze.

Light protection: During storage, minimize exposure to room light and avoid direct sunlight and ultraviolet light.

Room temperature window: Once removed from the refrigerator, mFlusiva may be kept between 8°C and 25°C (46°F to 77°F) for up to 12 hours.

No return to the refrigerator: Once a syringe has been at room temperature, it cannot go back into refrigerated storage.

This one-way rule is the biggest source of avoidable waste. Pulling doses ahead of a busy clinic day can mean discarding them at the end of it. Remove only what you plan to administer, and track when each syringe leaves the unit.

Avoid product mix-ups: Your storage unit may now hold several flu vaccines with different age indications, along with other mRNA products. Clear labeling and dedicated bins help ensure patients under 50 don’t receive mFlusiva in error.

mFlusiva Dosing and Administration Quick Reference

mFlusiva Contraindications, Warnings, and Precautions

Contraindication: Do not administer to patients who have had a severe allergic reaction to any of its ingredients.

Warnings and precautions from the label:

• Anaphylaxis: Appropriate medical treatment must be immediately available to manage potential anaphylactic reactions.
• Guillain-Barré Syndrome: If GBS occurred within 6 weeks of a previous flu vaccination, carefully weigh the risks and benefits before administering.
• Syncope: Fainting can occur with injectable vaccines, so have procedures in place to prevent injury.
• Immunocompromised patients: Those on immunosuppressive therapy may have a diminished immune response.

Patient Counseling: Talking Points for mFlusiva

“It cannot give you the flu.” mFlusiva contains no virus, live or inactivated. It provides instructions for a single surface protein that cannot cause influenza.

“You may feel it for a day or two.” Arm soreness, fatigue, and headache are common and usually resolve in about 2 days.

“It’s egg-free.” Patients who ask about egg allergies can be reassured that mFlusiva contains no egg protein. Standard post-vaccination precautions still apply.

“Protection builds over about two weeks.” As with other flu vaccines, encourage patients to vaccinate early in the season.

mFlusiva Provider Checklist: Preparing Your Practice for the mRNA Flu Vaccine

• Confirm payer coverage for your patient mix before ordering
• Store at 2°C to 8°C, away from light, and never freeze
• Train staff on the 12-hour room-temperature limit and the no-return rule
• Label and separate mFlusiva from other flu and mRNA products
• Verify the 2026-2027 formula label and inspect each syringe
• Prepare patients for common side effects and have anaphylaxis treatment on hand

Protect Every mRNA Vaccine Dose With TruMed Smart Vaccine Storage

New vaccines bring new handling rules, and every discarded syringe means lost revenue and a missed opportunity to protect a patient. TruMed’s automated vaccine storage solutions help your team maintain precise temperatures, track every dose, and stay ready for seasonal surges, so you can focus on patient care instead of fridge logs.

Preparing for respiratory season? Contact the TruMed Account Team to explore storage integration and clinical support resources.

This article is for informational purposes only. Always refer to the full FDA prescribing information for mFlusiva and current CDC guidance.