Sanofi has announced the acquisition of Dynavax Technologies in a significant deal valued at $2.2 billion, aimed at enhancing its vaccine offerings. The acquisition, disclosed on Wednesday, entails Sanofi purchasing Dynavax shares for $15.50 each, which reflects a 39% premium over Dynavax’s closing stock price on Tuesday. Founded in 2004 and based in Emeryville, California, Dynavax is known for its hepatitis B vaccine, Heplisav B, which is currently its only commercialized product.
This acquisition positions Sanofi to potentially gain competitive advantages over rival vaccine manufacturer GSK, as it expands its capabilities in adult immunization. Heplisav B, approved for use in both the United States and Europe, is given in a two-dose regimen one month apart. In contrast, GSK’s hepatitis B vaccine, Engerix-B, requires a three-shot series over six months, along with Twinrix, which protects against both hepatitis A and B.
Dynavax has reported impressive sales figures, with $268.4 million in Heplisav B revenue for 2024, marking a 26% increase from the previous year. The company also indicated that its market share for hepatitis B vaccines rose to 46% in 2025, up from 44% in 2024. Sanofi’s current offerings in this category primarily focus on vaccines for children, including Vaxelis, which protects against hepatitis B among other illnesses.
Strategic Expansion of Vaccine Offerings
The acquisition of Dynavax not only enhances Sanofi’s adult vaccination portfolio but is also viewed as a strategic response to emerging regulatory challenges in the vaccine market. The Advisory Committee on Immunization Practices (ACIP) recently recommended a shared decision-making approach for hepatitis B vaccinations for children, a shift from its longstanding recommendation for vaccinations to commence at birth.
According to Matt Phipps, an analyst at William Blair, the acquisition aligns with Dynavax’s need to address regulatory scrutiny and investor concerns regarding its growth strategy. Phipps noted that partnering with Sanofi is a logical move, given Sanofi’s established expertise in vaccines, particularly in areas where Dynavax lacks a presence, such as adult hepatitis B and shingles.
Dynavax is also advancing its pipeline, which includes a shingles vaccine candidate, Z-1018. Preliminary data from an early-stage study showed promising results compared to GSK’s dominant Shingrix vaccine, indicating better tolerability and a robust immune response across all tested doses. Results from further stages of the study are expected in the latter half of 2026.
The Dynavax acquisition is Sanofi’s second major vaccine deal this year. In July, the company announced its intention to acquire Vicebio for $1.15 billion, further diversifying its vaccine portfolio with a bivalent vaccine currently in early development for respiratory syncytial virus (RSV) and human metapneumovirus (hMPV).
Implications for the Future
Sanofi will fund the Dynavax acquisition through its existing cash resources. The deal has been approved by the Dynavax board of directors but is still subject to approval from a majority of shareholders. The transaction is anticipated to close in the first quarter of 2026.
As the global vaccine landscape evolves, Sanofi’s strategic acquisition of Dynavax reflects a proactive approach to bolster its position in the competitive pharmaceutical market, addressing both current and future public health challenges. The integration of Dynavax’s innovative products and technologies is expected to enhance Sanofi’s commitment to providing comprehensive vaccine options across the lifespan.
