Sanofi Expands Respiratory Vaccine Portfolio by Buying Vicebio

French biopharma company Sanofi will acquire Vicebio Ltd, a privately held biotechnology company headquartered in London, UK for $1.15 billion with potential milestone payments of up to $450 million based on development and regulatory achievements.

The transaction, which is expected to close in Q4 2025 subject to customary closing conditions, including receipt of regulatory approvals, will not have a significant impact on Sanofi’s financial guidance for 2025.

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 stabilises 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.

Jean-François Toussaint, Global Head of Research and Development Vaccines at Sanofi, said that 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.

More protection to Elders

“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 immunisation,” Toussaint added.

Vicebio CEO Emmanuel Hanon said that Sanofi’s global scale and deep expertise in vaccine development provide the ideal environment to fully realise the potential of their innovative technology.

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.

Sanofi applies its 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.

Its team is guided by one purpose: chasing the miracles of science to improve people’s lives, which inspires Sanofi to drive progress and deliver positive impact for its people and the communities it serves, by addressing the most urgent healthcare, environmental, and present societal challenges.