Sanofi has entered into an agreement to acquire Dynavax Technologies Corporation, a vaccines company with a marketed adult hepatitis B vaccine (Heplisav-B®) and a shingles vaccine candidate. The acquisition is valued at approximately $2.2 billion, with Dynavax stockholders set to receive $15.50 in cash per share, representing a 39% premium to Dynavax's closing share price on December 23, 2025.
Heplisav-B, Dynavax's adult hepatitis B vaccine, is marketed in the US and is differentiated by its two-dose regimen over one month, which allows for faster seroprotection compared to other hepatitis B vaccines that require three doses over six months. Sanofi's acquisition also includes Dynavax’s shingles vaccine candidate (Z-1018), currently in phase 1/2 clinical development, and additional vaccine pipeline projects.
The transaction, unanimously approved by the Dynavax board of directors, is expected to close in the first quarter of 2026, subject to customary closing conditions. Sanofi plans to fund the acquisition with available cash resources.
Heplisav-B, an adult hepatitis B vaccine, combines hepatitis B surface antigen with Dynavax’s vaccine adjuvant, a toll-like receptor (TLR) 9 agonist, to enhance the immune response. It is administered to adults 18 years of age and older in two doses, one month apart.
The most common patient-reported adverse reactions to Heplisav-B within 7 days of vaccination were injection site pain (23%-39%), fatigue (11%-17%), and headache (8%-17%). It is not recommended for individuals with a history of severe allergic reactions after a previous dose of any hepatitis B vaccine or to any component of Heplisav-B, including yeast.
Dynavax's CEO, Ryan Spencer, expressed confidence in the transaction, stating that joining Sanofi will provide the global scale and expertise needed to maximize the impact of their vaccine portfolio. Today the company's shares have moved 1.06% to a price of $10.985. If you want to know more, read the company's complete 8-K report here.
