Press Release: Sanofi to acquire Vicebio, expanding respiratory vaccines pipeline

Sanofi to acquire Vicebio, expanding respiratory vaccines pipeline

Paris, July 22, 2025. Sanofi today announces it has entered into an agreement to acquire Vicebio Ltd (“Vicebio”), a privately held biotechnology company headquartered in London, UK. The acquisition brings an early-stage combination vaccine candidate for respiratory syncytial virus (RSV) and human metapneumovirus (hMPV), both respiratory viruses, and expands the capabilities in vaccine design and development with Vicebio’s ‘Molecular Clamp’ technology.

The vaccine candidate complements Sanofi’s position in the respiratory vaccines space where the company is present in flu and RSV prevention. It allows Sanofi to offer increased physician and patient choice in RSV and hMPV by adding a non-mRNA vaccine to its pipeline.

In addition, the acquisition adds ‘Molecular Clamp’, an innovative technology that stabilizes viral proteins in their native shape, enabling the immune system to recognize and respond to them more effectively. This approach enables quicker development of fully liquid combination vaccines that can be stored at standard refrigeration temperatures (2–8°C), eliminating the need for freezing or freeze-drying, thereby simplifying manufacturing and distribution. Furthermore, fully liquid vaccines can be made available in prefilled syringes, enhancing ease of use, safety, and operational efficiency across healthcare settings. 

"Vicebio's ‘Molecular Clamp’ technology introduces a purposefully simple but thoughtful approach to further improve vaccine designs at a time when respiratory viral infections continue to impact millions globally”, said Jean-François Toussaint, Global Head of Research and Development Vaccines at Sanofi. “This acquisition furthers Sanofi's dedication to vaccine innovation with the potential to develop next-generation combination vaccines that could provide protection to older adults against multiple respiratory viruses with a single immunization."

“We are excited to join Sanofi”, said Emmanuel Hanon, Chief Executive Officer at Vicebio. “Their global scale and deep expertise in vaccine development provide the ideal environment to fully realize the potential of our innovative technology. As part of the Sanofi team, we look forward to advancing our platform and pipeline to deliver meaningful benefits for patients and public health.”

Vicebio’s pipeline includes VXB-241, a bivalent vaccine candidate targeting RSV and hMPV, currently in an exploratory phase 1 study in older adults, and VXB-251, a preclinical trivalent vaccine candidate targeting RSV, hMPV and parainfluenza virus Type 3 (PIV3). RSV, HMPV and PIV3 are leading causes of lower respiratory tract infections such as pneumonia. While often causing overlapping symptoms such as cough, fever, and respiratory distress, these viruses are antigenically distinct, frequently co-circulating and contributing to seasonal surges in respiratory illness that can lead to older adult frailty, hospitalization and, in some cases, death.

Financial considerations

Under the terms of the agreement, Sanofi would acquire all of Vicebio’s share capital for a total upfront payment of $1,15 billion, with potential milestone payments of up to $450 million based on development and regulatory achievements. The transaction is expected to close in Q4 2025, subject to customary closing conditions, including receipt of regulatory approvals. The acquisition will not have a significant impact on Sanofi’s financial guidance for 2025.

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

About Vicebio

Vicebio is focused on developing next-generation respiratory virus vaccines using the Molecular Clamp Technology. The company was founded with investment from Medicxi and acquired the rights to the Molecular Clamp technology through a license from UniQuest, the commercialization arm of The University of Queensland, Australia. This proprietary technology was developed by Prof. Paul Young, Prof. Daniel Watterson, and Prof. Keith Chappell at UQ. For more information, please visit:

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