Full approval in adults 50 to 64 years rests on results from the randomized, double-blind, active-controlled Phase 3 FLUENT trial (NCT06602024), which enrolled 40,805 adults aged ≥ 50 years across 301 sites in 11 countries.² Participants received a single intramuscular dose of trivalent mRNA-1010 (37.5 μg) or a licensed standard-dose comparator, with a median follow-up of 181 days.² RT-PCR-confirmed, protocol-defined influenza-like illness occurred in 2% of mRNA-1010 recipients compared with 2.8% of recipients of the standard-dose comparator.²
This difference corresponded to a relative vaccine efficacy of 26.6% (95% confidence interval [CI] 16.7 to 35.4), meeting prespecified thresholds for noninferiority, superiority, and higher-level superiority (P <.001).² Among the 19,260 participants aged ≥ 65 years, relative vaccine efficacy was 27.4% (95% CI, 12.1 to 40.0).²
Approval in adults aged ≥ 65 years followed a separate randomized, observer-blind, active-controlled trial (NCT05827978) enrolling 2992 US adults in this age group.¹ This study compared immunogenicity of mFLUSIVA against a high-dose inactivated influenza vaccine comparator, and the accelerated approval designation for adults aged ≥ 65 years rests on this immunogenicity bridge rather than confirmed clinical efficacy.¹ Descriptive rVE data from the FLUENT trial provide additional support in this population.
mFLUSIVA Safety Profile and Regulatory Pathway
Frequently Asked Questions
What is mFLUSIVA approved for?
mFLUSIVA (mRNA-1010) is approved for active immunization against seasonal influenza caused by influenza A and B strains in adults aged ≥ 50 years, with full approval for those 50 to 64 years and accelerated approval for those aged ≥ 65 years.
How does mFLUSIVA work?
mFLUSIVA uses messenger RNA technology to instruct cells to produce influenza surface antigens, prompting an immune response without live or inactivated virus, the same platform underlying Moderna's COVID-19 and RSV vaccines.
What did the pivotal trial for mFLUSIVA evaluate?
The Phase 3 FLUENT trial evaluated safety, reactogenicity, and relative vaccine efficacy of mFLUSIVA against a standard-dose comparator in 40,805 adults aged ≥ 50 years across 11 countries.
Moderna reported an acceptable safety profile across the phase 3 program, with no new safety signals identified and results consistent with previously reported mFLUSIVA studies.¹ Injection site reactions included pain, tenderness, swelling of lymph nodes in the injected arm, induration, and redness.¹ Systemic reactions included fatigue, headache, muscle pain, joint pain, chills, nausea or vomiting, and fever.¹ Severe allergic reactions were rare but can occur, typically within minutes to 1 hour after vaccination, and mFLUSIVA carries a contraindication in individuals with a history of severe allergic reaction to any vaccine component.¹
The accelerated approval pathway for adults aged ≥ 65 years is contingent on verification of clinical benefit in a confirmatory postmarketing trial. Beyond the US, mRNA-1010 has been accepted for regulatory review in the European Union, Canada, and Australia, with additional country submissions planned during 2026.¹
Moderna expects mFLUSIVA to reach select US retailers within the coming weeks, positioning the vaccine for the 2026-2027 respiratory virus season alongside Spikevax, mRESVIA, and mNEXSPIKE.¹ The FLUENT trial's descriptive rVE analysis and the ongoing postmarketing study in older adults will shape how the vaccine's efficacy data mature over the coming seasons.²
References
Leroux-Roels I, Huang G, Ferguson M, et al. Efficacy and Safety of an mRNA Seasonal Influenza Vaccine in Adults. N Engl J Med. 2026;394(18):1803-1813. doi:10.1056/NEJMoa2516491