Sanofi Bets Big on Adult Vaccines with $2.2B Dynavax Acquisition

Recently, Sanofi announced the acquisition of Dynavax at a cash price of $15.50 per share, with a total transaction value of approximately $2.2 billion.

Notably, this is already Sanofi's second acquisition in the vaccine field in 2025. Previously, Sanofi acquired Vicebio for $1.6 billion, obtaining a respiratory combination vaccine product in the clinical stage.

Continuous investment in the vaccine sector demonstrates the firm confidence of this European pharmaceutical giant in its long-term focus area, and represents a "contrarian" strategic bet amid an adjustment period for the vaccine industry.

01

Targeting Adult Vaccines

Through the acquisition of Dynavax, Sanofi has obtainedTwo Important Vaccine Assets。

FirstlyThe marketed adult hepatitis B vaccine Heplisav-B will help enrich Sanofi's adult immunization portfolio.

The vaccine was approved in 2017 for use in individuals aged 18 years and above. ItsThe biggest advantage is that only two doses are required for the entire course., with an interval of at least one month, significantly surpasses the traditional hepatitis B vaccine regimen of "three doses over six months," enhancing the convenience and compliance of vaccination.

Clinical trials show that the seroconversion rate of antibodies produced by the two-dose regimen of Heplisav-B is even higher than that of the three-dose regimen of Engerix-B, a hepatitis B vaccine from GSK. This is mainly due to the unique adjuvant CpG1018 in this vaccine, which is an oligonucleotide containing CpG motifs and primarily used to activate the TLR9 receptor on innate immune cells. This promotes the activation of various immune cells, enhances the adaptive immune response induced by the vaccine, prolongs antigen retention time in the body, protects the antigen from enzymatic degradation, increases circulating antibody levels or induces more effective protective immunity, and enhances the ability to elicit cell-mediated hypersensitivity responses.

Heplisav-B Achieves $268 Million in Sales in 2024, a Year-on-Year Increase of 26%, Demonstrating Strong Growth Momentum; Sales Projected to Exceed $900 Million by 2030.

Previously, Sanofi already had Vaxelis, a combined hepatitis B vaccine for infants. This is a hexavalent vaccine jointly developed with Merck, suitable for infants aged 6 weeks to 4 years, preventing pertussis, diphtheria, tetanus, poliomyelitis, hepatitis B, and invasive diseases caused by Haemophilus influenzae type B.

The current vaccine policy in the U.S. is undergoing significant changes. The CDC's Advisory Committee on Immunization Practices (ACIP), reorganized under Kennedy, recently voted to abandon the 34-year recommendation of "hepatitis B vaccination for all newborns," now limiting it to only those newborns whose mothers are infected or of unknown infection status.

AndHeplisav-B's adult indication positioning allows it to avoid the impact of potential adjustments to infant hepatitis B vaccination policies in the U.S.

Second, it is inThe candidate shingles vaccine Z-1018 in Phase 1/2 clinical trials is expected to open up a new multi-billion-dollar market for Sanofi.

Herpes Zoster: An infectious skin disease caused by the varicella-zoster virus. Globally, approximately one-third of people will be affected by herpes zoster at some point in their lifetime.

Currently, the global herpes zoster vaccine market is dominated by GSK's Shingrix, which was approved by the FDA in October 2017 for the prevention of herpes zoster in adults aged 50 and above, and in July 2021, its use was expanded to include high-risk individuals aged 18 and above with immune deficiency/suppression for the prevention of herpes zoster.

In the first three quarters of 2025, Shingrix sales reached $3.365 billion. In the third quarter alone, Shingrix sales amounted to £830 million ($1.1 billion), a year-over-year increase of 13%, ranking fifth in global vaccine sales. It is also the only vaccine among the top five to achieve positive sales growth.

With Z-1018, Sanofi is well-positioned to quickly enter this rapidly growing market.

The first phase data of the Phase 1/2 study of Z-1018 showed that the humoral vaccine response rate reached 100% one month after the second dose (this indicator is used to measure antibody production), compared to a response rate of 96.9% in the Shingrix control group.

In terms of the response to gE-specific CD4+ T cells, the cellular immune response rate was 89.7% in the Z-1018 group and 93.5% in the Shingrix group.

And due to the use of the CpG1018 adjuvant, Z-1018 demonstrated good tolerability, with 12.5% of patients reporting grade 2 or 3 injection-site adverse reactions and 27.5% reporting grade 2 or 3 systemic adverse reactions. In contrast, the incidence of adverse reactions in the Shingrix control group was higher, reaching 52.6% and 63.2%, respectively.

Good immunogenicity and tolerability,有望为Sanofi打开一个数十亿美元规模的新市场。

02

Accelerate M&A

Before acquiring Dynavax, Sanofi had also conducted several major M&A deals in 2025:

In June, Sanofi reached a high of$9.5 Billion Acquisition of Blueprint Medicines, acquiring the company's portfolio of treatments for rare immune diseases, including the systemic mastocytosis (SM) drug Ayvakit. The drug generated approximately $479 million in sales in 2024, with the company projecting its peak sales to reach $2 billion.

In July, Sanofi at a total price of up to$1.6 Billion Acquisition of Vaccine Company Vicebio`, obtaining the RSV+hMPV bivalent vaccine VXB241, the RSV+hMPV+PIV3 trivalent vaccine VXB-251, and Vicebio's "molecular clamp" technology platform.`

Behind Sanofi's frequent mergers and acquisitions is an urgent strategic response under multiple pressures.

ItsFlagship Product DupixentAlthough still in the growth phase, the recently approved COPD indication is expected to further expand its market potential; however, its active ingredientThe patent will expire in 2031.。

Although it is still several years away, given that Dupixent accounts for more than one-third of Sanofi's total revenue, Sanofi has no choice but to plan ahead and seek alternative products to reduce its reliance on this mega blockbuster drug.

Sanofi's R&D pipeline, however, has repeatedly faced challenges.

Recently, Sanofi announced that its autoimmune BTK inhibitor tolebrutinib did not meet the primary endpoint in the Phase 3 PERSEUS study for primary progressive multiple sclerosis (PPMS). A few days later, Sanofi received a Complete Response Letter (CRL) from the FDA regarding the marketing application for tolebrutinib to treat adult patients with non-relapsing secondary progressive multiple sclerosis (nrSPMS).

In May 2025, Sanofi announced the latest Phase III clinical data for its subcutaneous IL-33 monoclonal antibody Itepekimab in treating COPD (Chronic Obstructive Pulmonary Disease). AERIFY-1 met the primary endpoint with a significant reduction in moderate to severe exacerbations, but AERIFY-2 did not achieve this primary endpoint.

In April 2025, Sanofi announced that the highest dose group of its OX40L monoclonal antibody Amlitelimab failed to meet the primary endpoint in the Phase 2 TIDE-Asthma study for asthma. Even in the medium and low dose groups, only "minimal effects" were observed.

In addition, although the drug reached the primary endpoint and all key secondary endpoints in the Phase 3 clinical COAST 1 study for atopic dermatitis, its competitiveness is not favored by the market. Its efficacy level shows no significant advantage in non-head-to-head comparisons with Dupixent.

This drug was once listed by Sanofi as a candidate with potential peak sales exceeding 5 billion euros, but its disappointing performance in these two indications has cast a shadow over the future of this potential blockbuster drug.

Traditional vaccine business also showed signs of fatigue.

Q3 2025 Earnings Report Shows Sanofi's Total Vaccine Sales at €3.4 Billion, Down Nearly 8%, Attributed to "Decline in Flu Vaccine Sales"

03

Consolidate the Basic Market

Vaccine business is one of Sanofi's main performance pillars., contributing nearly 30% of the company's revenue.

Therefore, despite the dual challenges of shifting vaccine policies in the U.S. and market volatility, Sanofi has chosen to reinforce and expand this core lifeline through strategic acquisitions. This is not merely a case of expanding against the trend but rather anchoring on the most certain path of endogenous growth amid uncertainty.

Sanofi's traditional vaccine business has long been heavily reliant on flu vaccines, which are closely related to seasonality. This is precisely the main reason for the decline in its vaccine performance in the third quarter of 2025.

This acquisition of Dynavax adds a commercially available, stable-demand adult hepatitis B vaccine (Heplisav-B) and a highly promising blockbuster shingles candidate vaccine to its vaccine product portfolio.

Therefore, this seemingly contrarian "bold gamble" is in fact a prudent decision by Sanofi at a crossroads, channeling resources into the vaccine sector where it is most experienced and holds the greatest advantage. This move not only deepens its traditional strengths but also builds a future growth engine, demonstrating the strategic resolve of a multinational pharmaceutical company in a complex environment.

References

1.https://www.fiercepharma.com/pharma/acquisitive-sanofi-keeps-deals-coming-laying-out-22b-hepatitis-vaccine-maker-dynavax

2. Q&A on Vaccination: Package and Instructions for Hepatitis B Vaccine (US Dynavax, Trade Name Heplisav-B)

3. Tongxiyi "FDA Policy 'Big Year'"

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