Exhibit 99.1


Press Release

Sanofi completes the acquisition of Dynavax

Paris, February 10, 2026. Sanofi today announced that it has completed the acquisition of Dynavax Technologies Corporation (Dynavax). The acquisition includes Dynavax’s adult hepatitis B vaccine HEPLISAV-B, which is currently marketed in the US and is differentiated by its two-dose regimen over one month. It also includes Dynavax’s shingles vaccine candidate (Z-1018), which is currently in phase 1/2 studies, and additional vaccine pipeline projects.

This acquisition augments Sanofi’s presence in adult immunization by bringing together Dynavax’s vaccines with Sanofi’s commercial reach, global scale, and development capabilities.

The tender offer for all outstanding shares of Dynavax common stock, par value $0.001 per share expired one minute after 11:59 P.M. EST, on February 9, 2026. The minimum condition and all the other conditions to the offer have been satisfied, and on February 10, 2026, Sanofi accepted for payment and will promptly pay for all shares validly tendered and not validly withdrawn.

Following its acceptance of the tendered shares, Sanofi completed its acquisition of Dynavax through the merger of a wholly owned subsidiary of Sanofi with and into Dynavax, pursuant to Section 251(h) of the General Corporation Law of the State of Delaware, with Dynavax continuing as the surviving corporation and becoming an indirect, wholly owned subsidiary of Sanofi. In connection with the merger, all Dynavax shares not validly tendered in the tender offer have been converted into the right to receive the same $15.50 per share in cash, without interest, subject to any applicable withholding taxes, that would have been paid had such shares been validly tendered in the tender offer. As of February 10, 2026, Dynavax common stock will cease to be traded on the NASDAQ Global Select Stock Market.

About Sanofi

Sanofi is an R&D driven, AI-powered biopharma company committed to improving people’s lives and delivering compelling growth. We apply our deep understanding of the immune system to invent medicines and vaccines that treat and protect millions of people around the world, with an innovative pipeline that could benefit millions more. Our team is guided by one purpose: we chase the miracles of science to improve people’s lives; this inspires us to drive progress and deliver positive impact for our people and the communities we serve, by addressing the most urgent healthcare, environmental, and societal challenges of our time. Sanofi is listed on EURONEXT: SAN and NASDAQ: SNY

Media Relations

Sandrine Guendoul | +33 6 25 09 14 25 | sandrine.guendoul@sanofi.com

Evan Berland | +1 215 432 0234 | evan.berland@sanofi.com

Léo Le Bourhis | +33 6 75 06 43 81 | leo.lebourhis@sanofi.com

Victor Rouault | +33 6 70 93 71 40 | victor.rouault@sanofi.com

Timothy Gilbert | +1 516 521 2929 | timothy.gilbert@sanofi.com

Léa Ubaldi | +33 6 30 19 66 46 | lea.ubaldi@sanofi.com

Ekaterina Pesheva | +1 410 926 6780 | ekaterina.pesheva@sanofi.com

Investor Relations

Thomas Kudsk Larsen | +44 7545 513 693 | thomas.larsen@sanofi.com

Alizé Kaisserian | +33 6 47 04 12 11 | alize.kaisserian@sanofi.com

Keita Browne | +1 781 249 1766 | keita.browne@sanofi.com

Nathalie Pham | +33 7 85 93 30 17 | nathalie.pham@sanofi.com

Nina Goworek | +1 908 569 7086 | nina.goworek@sanofi.com

Thibaud Châtelet | +33 6 80 80 89 90 | thibaud.chatelet@sanofi.com

Yun Li | +33 6 84 00 90 72 | yun.li3@sanofi.com

Sanofi forward looking statement

Forward-looking statements are statements that are not historical facts. These statements may include projections and estimates regarding the marketing and other potential of the product, or regarding potential future revenues from the product, and their underlying assumptions, statements regarding plans, objectives, intentions, and expectations with respect to future financial results, events, operations, services, product development and potential, and statements regarding future performance. Forward-looking statements are generally identified by the words “expects”, “anticipates”, “believes”, “will be”, “intends”, “estimates”, “plans” and similar expressions. Although Sanofi’s management believes that the expectations reflected in such forward-looking statements are reasonable, investors are cautioned that forward-looking information and statements are subject to various risks and uncertainties, many of which are difficult to predict and generally beyond the control of Sanofi, that could cause actual results and developments to differ materially from those expressed in, or implied or projected by, the forward looking information and statements. These risks and uncertainties include among other things, unexpected regulatory actions or delays, or government regulation generally, that could affect the availability or commercial potential of the product, the fact that product may not be commercially successful and other risks associated with executing business combination transactions, such as the risk that the businesses will not be integrated successfully, that such integration may be more difficult, time-consuming or costly than expected or that the expected benefits of the acquisition will not be realized, risks related to future opportunities and plans for the combined company, including uncertainty of the expected financial performance and results of the combined company following completion of the proposed acquisition, disruption from the proposed acquisition making it more difficult to conduct business as usual or to maintain relationships with customers, employees, manufacturers, suppliers or patient groups, and the possibility that, if the combined company does not achieve the perceived benefits of the proposed acquisition as rapidly or to the extent anticipated by financial analysts or investors, the market price of Sanofi’s shares could decline, as well as other risks related to Sanofi’s business, including the ability to grow sales and revenues from existing products and to develop, commercialize or market new products, competition, including potential generic competition, the uncertainties inherent in research and development, including future clinical data and analysis, regulatory obligations and oversight by regulatory authorities, such as the FDA or the EMA, including decisions of such authorities regarding whether and when to approve any drug, device or biological application that may be filed for any product candidates as well as decisions regarding labelling and other matters that could affect the availability or commercial potential of any product candidates, the absence of a guarantee that any product candidates, if approved, will be commercially successful, the future approval and commercial success of therapeutic alternatives, Sanofi’s ability to benefit from external growth opportunities, to complete related transactions and/or obtain regulatory clearances, risks associated with existing clinical data relating to the product, including post marketing, unexpected safety, quality or manufacturing issues, competition in general, risks associated with intellectual property and any related pending or future litigation and the ultimate outcome of such litigation, trends in exchange rates and prevailing interest rates, volatile economic and market conditions, cost containment initiatives and subsequent changes thereto, and the impact that global crises may have on us, our customers, suppliers, vendors, and other business partners, and the financial condition of any one of them, as well as on our employees and on the global economy as a whole. The risks and uncertainties also include the uncertainties discussed or identified in the public filings with the US Securities and Exchange Commission (the “SEC”) and the Autorité des marchés financiers made by Sanofi, including those listed under “Risk Factors” and “Cautionary Statement Regarding Forward-Looking Statements” in Sanofi’s annual report on Form 20-F for the year ended December 31, 2024. Other than as required by applicable law, Sanofi does not undertake any obligation to update or revise any forward-looking information or statements.

Sanofi 6-K