Sanofi’s high-dose influenza vaccine demonstrates superior efficacy in protecting older adults from hospitalization compared to standard doses
Compared to standard-dose influenza vaccine, Efluelda/Fluzone High-Dose demonstrated an additional 31.9% (95% CI, 19.7 to 42.2; p<0.001) reduction in laboratory-confirmed influenza hospitalizations in adults 65 years and older. The results come from FLUNITY-HD, the largest individually randomized influenza vaccine efficacy study in older adults, with about half participating. FELDA/Fluzone High Dose also provided superior protection against pneumonia and influenza hospitalizations, cardiopulmonary hospitalizations, and all-cause hospitalizations in older adults compared to standard-dose influenza vaccine*. FELDA/Fluzone High Dose is the first vaccine to demonstrate excellent protection against both influenza infection and influenza. Hospital admissions compared with standard-dose influenza vaccine in an individual randomized study of adults 65 years and older
Paris, October 20, 2025. New data from the FLUNITY-HD study, published in The Lancet on October 17, demonstrated that Sanofi’s E-Ferda (known in North America as Fluzone High Dose) significantly reduced the risk of hospitalization in adults 65 and older compared to standard-dose influenza vaccines. FLUNITY-HD is the largest study of its kind conducted over multiple seasons and provides strong evidence that high-dose influenza vaccines provide superior protection compared to standard doses.
8.8% (95% CI, 1.7 to 15.5; one-sided p=0.008) Additional protection against pneumonia/influenza hospitalizations 6.3% (95% CI, 2.5 to 10.0; p<0.001) Additional reduction in hospitalizations due to cardiopulmonary events 31.9% (95% CI, 19.7 to 42.2; p<0.001) Additional laboratory-confirmed reduction Additional protective effect against all-cause hospitalizations for influenza hospitalizations of 2.2% (95% CI, 0.3 to 4.1; p=0.012). This means that one additional hospitalization could be avoided for every 515 people (95% CI, 278 to 3,929 people) vaccinated with Efuelda instead of the standard dose.
“The FLUNITY-HD study is unique in its design and scale, harnessing the power of individual randomization and scientific rigor in a real-world setting,” said cardiologist, principal investigator, and Professor Thor Bjering-Sørensen, sponsor of the FLUNITY-HD study. “The first-of-its-kind study evaluated the benefits of high-dose influenza vaccine on serious outcomes, including cardiopulmonary hospitalizations, compared with standard doses in a randomized setting across two geographic regions. Results provide important evidence and have the potential to reshape public health strategies and clinical guidelines.”
Professor Federico Martinon-Torres, co-principal investigator of the FLUNITY-HD study, added: “This new evidence supports medical experts’ confidence that high-dose influenza vaccines offer better protection than standard doses against severe outcomes in older people, who are considered vulnerable due to weakened immune systems and a higher risk of developing serious complications after influenza infection.”
Beyond clinical evidence, these findings demonstrate potential public health and societal benefits.
“Up to 70% of influenza hospitalizations are in adults over 65 years of age. FLUNITY-HD data confirms that our high-dose influenza vaccine provides superior protection against hospitalization compared to standard-dose vaccines in older adults,” said Bogdana Kuji, M.D., Global Medical Director, Vaccines, Sanofi. “For every 515 older adults who receive our high-dose influenza vaccine instead of the standard-dose vaccine, one all-cause hospitalization will be prevented. This has particularly significant implications for vulnerable older adults, reducing strain on their quality of life and helping them maintain their independence for longer. Additionally, preventing influenza hospitalizations may have societal benefits, including lower healthcare costs, less pressure on the healthcare system, and less burden on caregivers.”
With the addition of these new data, our comprehensive study of high-dose influenza vaccines now covers 15 years of clinical evidence across more than 45 million older adults.
About FLUNITY-HD research
FLUNITY-HD is a prespecified pooled analysis of two pragmatic individual randomized trials, DANFLU-2 and GALFLU, involving 466,320 participants aged 65 years and older. DANFLU-2 was conducted across three influenza seasons (2022-23, 2023-24, and 2024-25) among more than 332,000 participants aged 65 and older in Denmark. GALFLU was conducted over two influenza seasons (2023-24 and 2024-25) among more than 134,000 participants aged 65 to 79 in the Galicia region of Spain.
This multi-season analysis, the largest influenza vaccine study of its kind, was designed to evaluate the real-world effectiveness of FELDA (high-dose influenza vaccine) compared to standard-dose influenza vaccine in preventing hospitalizations, ensuring scientific rigor through independent randomization.
FLUNITY-HD met its primary endpoint, demonstrating 8.8% additional protection against pneumonia/influenza hospitalization (compared to standard dose). Secondary endpoints include reductions in hospitalizations for cardiopulmonary events, laboratory-confirmed influenza hospitalizations, and all-cause hospitalizations.
About Felda/Fluzone high dose
Efluelda is a high-dose influenza vaccine intended for adults aged 60 and older in Europe. It is licensed in North America under the brand name Fluzone High-Dose and is intended for adults 65 years and older.
This high-dose influenza vaccine is designed specifically for older adults, whose immune systems gradually decline and become weaker as we age, putting them at higher risk of severe influenza-related illness and hospitalization compared to younger adults. It provides four times more antigen compared to standard-dose vaccines, resulting in a better immune response to influenza in older adults.
About Sanofi
Sanofi is an R&D-driven, AI-powered biopharmaceutical company committed to improving people’s lives and delivering compelling growth. We apply our deep understanding of the immune system to invent medicines and vaccines that treat and protect millions of people around the world, and deliver a pipeline of innovations that have the potential to benefit millions more. Our team follows one purpose. It’s about pursuing scientific miracles to improve people’s lives. It motivates us to drive progress and positively impact our people and the communities we serve by addressing the most pressing medical, environmental and social challenges of our time.
Sanofi is listed on Euronext: SAN and Nasdaq: SNY.
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