Sanofi to acquire Dynavax in $2.2 billion deal, bolstering adult vaccine portfolio

The move strengthens Sanofi’s presence in adult immunization by combining Dynavax’s innovative vaccines with Sanofi’s global scale and development capabilities

Global pharma powerhouse Sanofi has announced that it has reached an agreement to acquire Dynavax Technologies Corporation, a publicly traded vaccines company known for its adult hepatitis B vaccine, HEPLISAV-B, and a promising shingles vaccine candidate.

The move strengthens Sanofi’s presence in adult immunization by combining Dynavax’s innovative vaccines with Sanofi’s global scale and development capabilities.

HEPLISAV-B, marketed in the US, is distinguished by its two-dose regimen over one month, providing faster and higher levels of protection compared with traditional three-dose hepatitis B vaccines spread over six months. The acquisition also includes Dynavax’s shingles vaccine candidate, Z-1018, currently in Phase 1/2 trials, along with other pipeline projects.

“Dynavax enhances Sanofi’s adult immunization presence by adding differentiated vaccines that complement Sanofi’s expertise,” said Thomas Triomphe, Executive Vice President, Vaccines, Sanofi. “Its marketed adult hepatitis B vaccine and shingles candidate bring new options to our portfolio and underscore our commitment to providing vaccine protection across the lifespan.”

Dynavax CEO Ryan Spencer emphasized the strategic benefits for his company: “Joining Sanofi will provide the global scale and expertise needed to maximize the impact of our vaccine portfolio."

"We believe Sanofi’s commercial reach, development capabilities, and commitment to evidence-based immunization will amplify the opportunity for HEPLISAV-B and our innovative pipeline to address important public health needs, further advancing our mission to help protect the world against infectious disease. We are confident that this transaction – and the compelling value it provides – is in the best interests of the Company and its stockholders.”

The deal targets significant adult vaccination opportunities in the US, where nearly 100 million adults born before 1991 remain unvaccinated. Hepatitis B can cause chronic liver damage, cirrhosis, and liver cancer, while shingles affects one in three adults over their lifetime, potentially leading to long-term nerve pain, serious eye infections, or rare but dangerous brain inflammation.

Under the terms of the agreement, Sanofi will launch a cash tender offer for all outstanding Dynavax shares at $15.50 per share, valuing the company at approximately $2.2 billion. The Dynavax board has unanimously approved the merger. The transaction is subject to standard regulatory approvals and other customary conditions. Following the tender offer, a Sanofi subsidiary will merge with Dynavax, converting any untendered shares into the same cash offer.

Sanofi plans to fund the acquisition from available cash, and the transaction is not expected to affect the company’s 2025 financial guidance. If all conditions are met, the deal is expected to close in the first quarter of 2026.