Press Release: Sanofi’s high-dose influenza vaccine demonstrates superior protection for older adults against hospitalization vs standard-dose

Sanofi’s high-dose influenza vaccine demonstrates superior protection for older adults against hospitalization vs standard-dose

• Compared to standard-dose influenza vaccines, Efluelda/Fluzone High-Dose demonstrated a reduction in laboratory-confirmed influenza hospitalizations by an additional 31.9% (95% CI, 19.7 to 42.2; p<0.001) in adults 65 years and over
• Results come from FLUNITY-HD, the largest influenza vaccine effectiveness study of individually randomized older adults, involving nearly half a million participants across several seasons and two geographic areas
• Efluelda/Fluzone High-Dose also provided superior protection, compared to standard-dose influenza vaccines*, against hospitalizations due to pneumonia or influenza, hospitalizations caused by cardio-respiratory events, and all-cause hospitalizations in older adults
• Efluelda/Fluzone High-Dose is the first vaccine to demonstrate superior protection against both influenza infection and hospitalizations, compared to standard-dose influenza vaccines, in individually randomized studies in adults 65 years and over

Paris, October 20, 2025. New data from the FLUNITY-HD study, published on October 17 in The Lancet, demonstrated that Sanofi's Efluelda (known as Fluzone High-Dose in North America) significantly reduced the risk of hospitalization in adults 65 years and older compared to standard-dose influenza vaccines. The largest study of its kind, conducted across multiple seasons, FLUNITY-HD provides robust evidence that the high-dose influenza vaccine offers superior protection compared to standard-dose:

• 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 for cardio-respiratory events
• 31.9% (95% CI, 19.7 to 42.2; p<0.001) additional reduction in lab-confirmed influenza hospitalizations
• 2.2% (95% CI, 0.3 to 4.1; p=0.012) additional protection against all-cause hospitalizations, meaning one additional hospitalization could be averted for every 515 (95% CI, 278 to 3,929) individuals vaccinated with Efluelda instead of standard-dose.

"The FLUNITY-HD study, unparalleled in its design and scale, harnesses the power and scientific rigor of individual randomization in real-world settings,” shared Professor Tor Biering-Sørensen, Cardiologist, Chief Investigator, and sponsor of the FLUNITY-HD study. “This first-of-its-kind study assessed the benefits of the high-dose influenza vaccine against severe outcomes compared to standard-dose, including against cardio-respiratory hospitalizations, in a randomized setting, covering two geographic areas. The results provide critical evidence, potentially reshaping public health strategies and clinical guidelines."

Professor Federico Martinon-Torres, Co-Principal Investigator of FLUNITY-HD study, added, “This new evidence reinforces the clinical confidence healthcare professionals have that the high-dose influenza vaccine achieves superior protection over standard-dose against severe outcomes in older adults, a group consideredvulnerable due to having a weakened immune system and a higher risk of developing serious complications after flu infection."

Beyond clinical evidence, these findings point to potential public health and societal benefits.

“Adults 65 and older represent up to 70% of flu hospitalizations. The FLUNITY-HD data confirm that our high-dose flu vaccine provides superior protection against hospitalizations compared to standard-dose vaccines in older adults,” said Bogdana Coudsy, MD, Global Head of Medical, Sanofi, Vaccines. “For every 515 older adults who receive our high-dose flu vaccine instead of standard-dose vaccines, one all-cause hospitalization is prevented. This can mean a lot, especially for vulnerable seniors, decreasing the burden on their quality of life and helping them to maintain their autonomy for longer. Additionally, preventing influenza hospitalizations may bring societal benefits such as lower healthcare costs, less pressure on medical systems, and reduced burden on caregivers.”

With the addition of these new data, comprehensive research on our high-dose influenza vaccine covers 15 years of clinical evidence spanning over 45 million older adults.

About the FLUNITY-HD Study
FLUNITY-HD is a pre-specified pooled analysis of two pragmatic individually randomized trials involving 466,320 participants aged 65 and older: DANFLU-2 and GALFLU. DANFLU-2 was conducted over three influenza seasons (2022-23, 2023-24 and 2024-25) with over 332,000 participants aged 65 and above in Denmark. GALFLU was conducted over two influenza seasons (2023-24 and 2024-25) with over 134,000 participants aged 65 to 79 in the region of Galicia in Spain.

The largest influenza vaccine study of its kind, this multi-season analysis is designed to evaluate the real-world effectiveness of Efluelda (high-dose influenza vaccine) compared to standard-dose influenza vaccines in preventing hospitalizations, ensuring scientific rigor through individual randomization.

FLUNITY-HD achieved its primary endpoint, demonstrating 8.8% additional protection against pneumonia/influenza hospitalizations (vs standard dose). Secondary endpoints include reduction in hospitalizations for cardio-respiratory events, lab-confirmed influenza hospitalizations and all-cause hospitalizations.

About Efluelda / Fluzone High-Dose
Efluelda is a high-dose influenza vaccine, indicated for adults aged 60 and older in Europe. It is also licensed under the brand name Fluzone High-Dose in North America where it is indicated for adults aged 65 and older.

This high-dose influenza vaccine is specifically tailored for older adults whose immune systems gradually decline and weaken with age, increasing their risk for severe influenza-related illness and hospitalization compared with younger populations. It provides 4x the antigen compared to a standard-dose vaccine to deliver a better immune response against influenza for older adults.

About Sanofi
Sanofi is an R&D driven, AI-powered biopharma 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, with an innovative pipeline that could benefit millions more. Our team is guided by one purpose: we chase the miracles of science to improve people’s lives; this inspires us to drive progress and deliver positive impact for our people and the communities we serve, by addressing the most urgent healthcare, environmental, and societal challenges of our time.

Sanofi is listed on EURONEXT: SAN and NASDAQ: SNY

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