Sanofi agreed to acquire Dynavax Technologies for $2.2 billion in cash, adding the commercial hepatitis B vaccine Heplisav‑B and a clinical‑stage shingles candidate to its vaccine portfolio. The deal, announced Dec. 24, consolidates Sanofi’s vaccine footprint and brings immediate commercial revenues alongside an R&D asset that could differentiate against incumbent shingles products. Dynavax’s marketed hepatitis B vaccine and its phase I/II shingles program were central to Sanofi’s bid; the package gives Sanofi both short‑term sales and mid‑term pipeline optionality. The transaction closed amid investor scrutiny over pricing and strategic focus in big‑pharma vaccine plays. The acquisition also comes as Sanofi reported a complete response letter for tolebrutinib, highlighting the company’s simultaneous push to shore up vaccine revenues while navigating pipeline setbacks. Heplisav‑B is an established product in the US market; tolebrutinib’s regulatory delay underscores why buyers value late‑stage or commercialized vaccine assets.