Sanofi to Acquire Dynavax for $2.2 Billion, Boosting Vaccine Unit
The all-cash deal, a 39% premium for Dynavax shareholders, adds the fast-growing HEPLISAV-B hepatitis B vaccine to the French drugmaker's portfolio.
French pharmaceutical giant Sanofi announced Tuesday a definitive agreement to acquire Dynavax Technologies for $2.2 billion in an all-cash deal, significantly strengthening its vaccines division with a marketed hepatitis B vaccine.
Under the terms of the agreement, Sanofi will pay $15.50 for each Dynavax share, representing a substantial 39% premium to Dynavax's closing price of $11.13 on Monday. Shares of Dynavax (NASDAQ: DVAX) surged nearly 38% in morning trading to just under the offer price, reflecting investor confidence that the deal will close as planned in the first quarter of 2026.
The centerpiece of the acquisition is HEPLISAV-B, an adult hepatitis B vaccine that has gained market share due to its superior clinical profile. According to company statements, HEPLISAV-B requires only two doses over one month, offering faster protection than the three-dose regimen over six months required by competing vaccines, such as GSK's Engerix-B. This differentiated profile is a key strategic asset for Sanofi as it looks to expand its leadership in adult immunizations.
"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. "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."
The deal continues a broader industry trend of large pharmaceutical firms acquiring smaller, innovative biotechs to fuel growth and replenish product pipelines. For Sanofi, the purchase adds a commercially successful product that complements its existing vaccine infrastructure and global commercial reach. The transaction also includes Dynavax’s early-stage shingles vaccine candidate, Z-1018, which is currently in Phase 1/2 development.
Dynavax's leadership framed the acquisition as a positive outcome for shareholders and the company's public health mission. "Joining Sanofi will provide the global scale and expertise needed to maximize the impact of our vaccine portfolio," said Ryan Spencer, Chief Executive Officer of Dynavax, in a press release. "We are confident that this transaction – and the compelling value it provides – is in the best interests of the Company and its stockholders."
With nearly 100 million American adults born before 1991 still unvaccinated for hepatitis B, the market opportunity remains significant. Sanofi's extensive commercial footprint is expected to accelerate the uptake of HEPLISAV-B globally.
The acquisition, which Sanofi will fund using available cash, is subject to customary closing conditions, including regulatory approvals and a vote by Dynavax stockholders. Given the significant premium and the high institutional ownership of Dynavax stock (over 98%), the deal is widely expected to be approved.