Sanofi SA ( SNY ) on Tuesday agreed to acquire Vicebio Ltd, a privately held biotechnology company headquartered in London, U.K.

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 ( SNY ) to offer increased physician and patient choice in RSV and hMPV by adding a non-mRNA vaccine to its pipeline.

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The acquisition also adds ‘Molecular Clamp,’ a technology stabilizing viral proteins in their native shape, enabling the immune system to recognize and respond to them more effectively.

The approach enables quicker development of fully liquid combination vaccines 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. 

Under the terms of the agreement, Sanofi ( SNY ) 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 the fourth quarter of 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.

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).

This acquisition reinforces Sanofi’s commitment to innovation in respiratory vaccines. In June, Sanofi ( SNY ) said it is shipping Beyfortus (nirsevimab) starting in early Q3 to ensure broad availability well ahead of the 2025-2026 RSV season, which typically starts in November and runs through March.

Sanofi ( SNY ), in collaboration with its partner AstraZeneca plc ( AZN ) , has tripled production capacity and doubled the number of manufacturing sites since the launch of Beyfortus in 2023.

This acquisition follows another significant move by Sanofi ( SNY ) in June 2025, when it agreed to acquire Blueprint Medicines Corporation for approximately $9.1 billion.

That acquisition included Ayvakit/Ayvakyt (avapritinib), a rare immunology disease medicine approved in the U.S. and the EU, along with a promising advanced and early-stage immunology pipeline.

Price Action: SNY stock is trading higher by 1.42% to $48.61 at last check Tuesday.

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