Sanofi has announced its acquisition of Dynavax Technologies for approximately $2.2 billion, a strategic move aimed at enhancing its vaccine portfolio. The deal, confirmed on Wednesday, involves Sanofi purchasing each share of Dynavax for $15.50 in cash, representing a 39% premium over the stock’s closing price on Tuesday. This acquisition could strengthen Sanofi’s competitive position against rival vaccine manufacturer GSK.
Dynavax, based in Emeryville, California, has been a player in the vaccine market since it went public in 2004, pricing its shares initially at $7.50 each. The company’s primary commercial product is Heplisav B, a hepatitis B vaccine approved for adults in both the U.S. and Europe. Unlike GSK’s hepatitis B vaccines, which require three shots over six months, Heplisav B is administered in just two injections one month apart.
The efficacy of Heplisav B is notable; Dynavax claims it allows patients to achieve high levels of protective antibodies faster than its competitors while maintaining a similar safety profile. The company reported $268.4 million in Heplisav B sales in 2024, marking a 26% increase from the previous year. This growth has helped Dynavax capture 46% of the hepatitis B vaccine market, a slight increase from 44% in 2023.
Sanofi currently focuses on hepatitis B vaccines for children, with Vaxelis being its main offering. Vaxelis, developed in partnership with Merck, protects against hepatitis B and five additional pathogens. The FDA approved Vaxelis in 2023 for children aged six weeks to four years, administered as a three-shot series.
Expanding Vaccine Pipeline
In addition to Heplisav B, Dynavax is developing a shingles vaccine candidate, Z-1018. Preliminary results from early-stage studies indicate that Z-1018 may be well tolerated and exhibit fewer side effects compared to GSK’s Shingrix, the current leader in the shingles vaccine market. These studies have also shown robust immune responses, and further data is expected in the latter half of 2026.
Thomas Triomphe, Sanofi’s executive vice president for vaccines, stated, “Dynavax enhances Sanofi’s adult immunization presence by adding differentiated vaccines that complement Sanofi’s expertise.” He emphasized that the acquisition reflects the company’s commitment to providing vaccine protection throughout a person’s life.
The announcement of this acquisition coincides with increasing scrutiny on hepatitis B vaccines. Recently, the Advisory Committee on Immunization Practices (ACIP) voted to recommend shared decision-making for hepatitis B vaccination in children, a shift from its longstanding recommendation for vaccinations to begin at birth.
According to William Blair analyst Matt Phipps, the acquisition aligns with emerging regulatory challenges in the vaccine landscape. He noted that Sanofi is a logical partner for Dynavax, given its extensive vaccine development capabilities, which currently lack an adult hepatitis B or shingles program.
Beyond the shingles vaccine, Dynavax’s pipeline includes a plague vaccine developed in collaboration with the U.S. Department of Defense, as well as clinical-stage programs targeting pandemic influenza and Lyme disease. Additionally, in November, Dynavax secured global rights to Vaxart’s oral Covid-19 vaccine candidate, which is in mid-stage testing, investing $25 million upfront and an additional $5 million in equity.
This acquisition marks Sanofi’s second significant vaccine-related merger this year. In July, the company agreed to acquire Vicebio for $1.15 billion, a startup focused on a bivalent vaccine for respiratory syncytial virus (RSV) and human metapneumovirus (hMPV).
Sanofi plans to finance the Dynavax acquisition using its available cash resources. While the Dynavax board has approved the deal, it still requires approval from a majority of shareholders. The transaction is anticipated to close in the first quarter of 2026.
