In a strategic development that’s set to reshape its vaccine business, Sanofi has announced an agreement to acquire Dynavax Technologies Corporation, a U.S.-based vaccines company known for its marketed adult hepatitis B vaccine and an early-stage shingles vaccine candidate. This deal is expected to significantly expand Sanofi’s presence in adult immunization and enhance its broader vaccine pipeline.
Under the terms of the agreement, Sanofi will offer to buy all outstanding Dynavax shares in cash at USD 15.50 per share, valuing the transaction at approximately USD 2.2 billion — a premium that has already lifted Dynavax’s stock in early trading. The offer has been approved unanimously by Dynavax’s board of directors and, if all the customary closing conditions are met, the acquisition could close in the first quarter of 2026.
At the heart of the deal is HEPLISAV-B®, Dynavax’s marketed adult hepatitis B vaccine, which is already sold in the United States. What makes this vaccine differentiated is its two-dose schedule over one month — a faster regimen than the traditional three doses spread over six months used by many competitors, potentially improving adult vaccination rates.
In addition to HEPLISAV-B, Sanofi will gain Z-1018, a shingles vaccine candidate currently in Phase 1/2 clinical development, plus other pipeline projects. Shingles, caused by the varicella-zoster virus, affects a significant share of adults during their lifetime and can lead to painful symptoms and complications. By adding this asset, Sanofi broadens its adult immunization portfolio in areas with major public health needs.
“Dynavax enhances Sanofi’s adult immunization presence by adding differentiated vaccines that complement Sanofi’s expertise,” said Thomas Triomphe, Executive Vice President of Vaccines at Sanofi. He noted that these assets support Sanofi’s commitment to providing vaccine protection across the lifespan.
From Dynavax’s perspective, Chief Executive Officer Ryan Spencer said joining Sanofi would provide the global scale and commercial reach needed to maximize the impact of HEPLISAV-B and the company’s innovative pipeline, furthering their mission to protect against serious infectious diseases.
The acquisition is part of a broader shift by Sanofi to diversify and strengthen its vaccine business, especially in adult immunization — a segment that has been drawing increasing attention from major pharmaceutical companies amid evolving public health trends and immunization needs.
Sanofi plans to fund the deal with existing cash resources and does not expect it to materially affect its financial guidance for 2025. The company will continue to operate and expand its vaccine offerings globally while integrating Dynavax’s assets into its development and commercial frameworks.
Industry watchers say this move could help Sanofi better compete in adult vaccines against established rivals, especially as demand grows for more convenient and effective immunization options. However, successful integration — both operational and cultural — will be critical once the transaction closes.
