Sanofi acquires Dynavax for $2.2 billion to bolster vaccine portfolio

Sanofi has agreed to acquire Dynavax Technologies, a vaccine development company whose pipeline includes a shingles vaccine candidate. Z-1018 is currently in phase 1/2 clinical development.

Shingles, which is caused by the varicella zoster virus, affects 1 in 3 adults over their lifetime, according to the World Health Organization. In most people, shingles causes a painful, itchy rash but, in some cases it can lead to long-term nerve pain, serious eye infections that can damage the vision, and, rarely, to dangerous inflammation of the brain.

In part 1 of the phase 1/2 study, Z-1018 demonstrated positive topline results compared with GSK’s Shingrix in healthy adults aged 50 to 69. About 40 participants were enrolled in each of the 10 Z-1018 groups and one Shingrix group. Z-1018 demonstrated immunogenicity that was comparable to Shingrix. All dosages and formulations in part 1 of the study were well-tolerated, with fewer post-injection site reactions than Shingrix through four weeks.

Dynavax has initiated part 2 of phase 1/2 trial evaluating Z-1018 to Shingrix in adults 70 years and older. About 324 healthy adults will be enrolled to test two doses at eight week intervals compared with Shingrix.

The company expects to report topline data from part 2 of the phase 1/2 trial, as well as the 12-month follow-up data for part 1, in the second half of 2026.

Dynavax markets the adult hepatitis B vaccine HEPLISAV-B, a vaccine that combines hepatitis B surface antigen with Dynavax’s vaccine adjuvant, a toll-like receptor (TLR) 9 agonist, to enhance the immune response. FDA officials are reviewing a biologic license application for HEPLISAV-B for adults on hemodialysis.

Dynavax’s pipeline also include an oral COVID-19 vaccine (licensed from Vaxart), a plague vaccine, a Lyme disease vaccine, and a pandemic flu (H5N1) vaccine.

In a news release, Sanofi officials said Dynavax’s vaccines complement its own expertise. “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,” said Thomas Triomphe, executive vice president, vaccines, Sanofi.

In the third quarter of 2025, Sanofi’s sales of vaccines decreased 78% compared with the same quarter in 2024, which the company said was from lower influenza sales. Sanofi markets several flu vaccines, including Fluzone, Fluzone high dose and Flublok. Sanofi also sells other vaccines, including for COVID-19; polio, pertussis, Hib and meningitis and other travel vaccines. Fourth quarter and full year 2025 results will be released Jan. 29, 2026.

Sanofi has several late-stage vaccines in its pipeline, including Fluzone high dose for those over the age of 50 (currently approved for those 65 and older) and vaccines for yellow fever, pneumococcal disease and rabies. In phase 2 trials are vaccines for meningitis and mRNA vaccines for RSV, flu and acne.

The acquisition is valued at $2.2 billion and is expected to close in the first quarter of this year.