Press Release


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 considered



*The standard-dose influenza vaccines used in the FLUNITY-HD study were VaxigripTetra (Sanofi) and InfluvacTetra (Viatris). Standard-dose vaccines often serve
as the primary influenza prevention option for the general population.
vulnerable 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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Investor Relations
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