Sanofi has reported that the high-dose formulation of its influenza vaccine, Elfueda (known as Fluzone High-Dose in the US), significantly reduced the risk of hospitalisation in older adults compared with standard-dose influenza vaccines.
The findings, published in The Lancet, are from Sanofi’s FLUNITY-HD study – an analysis of two randomised trials, DANFLU-2 and GALFLU. Together, the trials included 466,320 participants, making this one of the largest influenza vaccine studies conducted to date. DANFLU-2 was carried out across three influenza seasons in Denmark (2022–2025), while GALFLU was conducted over two seasons (2023–2025) in Galicia, Spain.
“The FLUNITY-HD study, unparalleled in its design and scale, harnesses the power and scientific rigour of individual randomisation in real-world settings,” said 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 hospitalisations, in a randomised setting, covering two geographic areas. The results provide critical evidence, potentially reshaping public health strategies and clinical guidelines.”
FLUNITY-HD met its primary endpoint, demonstrating a statistically significant reduction in pneumonia- and influenza-related hospitalisations from the high-dose vaccine compared with standard-dose formulations.
Secondary endpoints – including reductions in hospitalisations for cardio-respiratory events, laboratory-confirmed influenza and all-cause hospitalisations – also showed positive outcomes.
“Adults 65 and older represent up to 70% of flu hospitalisations. The FLUNITY-HD data confirm that our high-dose flu vaccine provides superior protection against hospitalisations compared to standard-dose vaccines in older adults,” said Bogdana Coudsy, 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 hospitalisation 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 hospitalisations may bring societal benefits such as lower healthcare costs, less pressure on medical systems and reduced burden on caregivers.”