Sanofi announces the acquisition of the American vaccine manufacturer Dynavax

Sanofi announces the acquisition of the American vaccine manufacturer Dynavax

December 24, 2025

French pharmaceutical giant Sanofi announced Wednesday that it has signed an agreement to acquire the American company Dynavax, which markets, among other things, a vaccine against hepatitis B for adults.

According to the agreement, Sanofi will launch a public cash tender offer to buy back all of the shares of Dynavax, a company listed in the United States, at a price of $15.50 per share, which values the company at approximately $2.2 billion, according to the Sanofi press release.

Dynavax is notably developing a vaccine candidate against shingles, which is "currently in phase 1/2 of clinical development", as well as other vaccine projects, adds the French laboratory.

Its adult hepatitis B vaccine, "Heplisav B", is currently marketed in the United States and is distinguished by its dosage of only two doses over one month, "which allows for high levels of seroprotection to be achieved more quickly than other vaccines", according to Sanofi.

These two vaccines "add new options to our portfolio and underline our commitment to providing lifelong vaccine protection," said Thomas Triomphe, Executive Vice President at Sanofi, quoted in the press release.

“Joining Sanofi will bring the global reach and expertise needed to maximize the impact of our vaccine portfolio,” added Ryan Spencer, CEO of Dynavax, who was also quoted.

Hepatitis B is a viral infection that attacks the liver. Its chronic form is responsible for more than 401% of cases of hepatocellular carcinoma (primary liver cancer), the second deadliest cancer in the world.

Shingles is a manifestation of the reactivation of the varicella-zoster virus, most often occurring in adults over the age of 50. After chickenpox, the virus remains dormant in human nerve cells and can reactivate later in life due to a triggering factor such as stress or immunosuppression.

While usually benign, this localized infection can lead to the appearance of painful plaques.

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