Data from the three-year follow-up study confirm that Cecolin 9, the E. coli-produced HPV 9-valent vaccine co-developed by Innovax and Xiamen University, maintains non-inferior type-specific plateau antibody levels compared to a marketedHPV 9-valent vaccine in Chinese women aged 18-26 years, supporting its potential for enduring protection against targeted HPV types.

Xiamen Innovax Biotech Co., Ltd. ("Innovax"), in collaboration with Xiamen University, announced in early September 2025 that three-year follow-up data from a head-to-head clinical study comparing the immunogenicity of Cecolin 9 (Recombinant human papillomavirus 9-valent vaccine, types 6/11/16/18/31/33/45/52/58,E. coli-produced) and a marketed HPV 9-valent vaccine in healthy Chinese women aged 18-26 years have been published in The Lancet Regional Health - Western Pacific (2025;62:101671), with the full text accessible via https://doi.org/10.1016/j.lanwpc.2025.101671. This extension study (ClinicalTrials.gov: NCT06197802) builds on a base study (NCT04782895) - which previously established Cecolin 9’s non-inferior immunogenicity vs. a marketed HPV 9-valent vaccine at 7 months post the first dose - to further evaluate the sustained plateau antibody levels, seropositivity rates, and antibody decay trends of both vaccines over three years (median follow-up time: 34 months).

As a next-generation HPV 9-valent vaccine developed based on the WHO-prequalified Cecolin (Innovax's HPV bivalent vaccine), Cecolin 9 has enabled China to become the second country after the United States with independent capability to produce high-valent HPV vaccines -supporting the WHO's Global Strategy for Cervical Cancer Elimination. Three-year follow-up data for Cecolin 9 further confirm its potential as an effective alternative to improve global access to protection against HPV types covered by 9-valent vaccines.

Key findings from this three-year follow-up study:

• Sustained non-inferior immunogenicity of Cecolin 9 vs. a marketed HPV 9-valent vaccine

Among 403 participants (82.8% retention rate from the base study; 200 in Cecolin 9 group, 203 in a marketed HPV 9-valent vaccine group), the geometric mean concentration (GMC) ratios of Cecolin 9 vs. a marketed HPV 9-valent vaccine for all nine HPV types ranged from 0.78 (95% CI: 0.64–0.95, HPV 11) to 1.91 (95% CI: 1.54–2.37, HPV 58). The lower bounds of 95% CIs spanning from 0.64 to 1.54, which exceeded 0.5—the threshold for non-inferiority — confirming that Cecolin 9's type-specific antibody levels remained non-inferior to a marketed HPV 9-valent vaccine at three years post the first dose.

• High and sustained seropositivity rates

Both vaccine groups maintained seropositivity rates >80% for all nine HPV types at three years post the first dose. Notably, HPV 16 seropositivityratesreached 100% in both groups, while other types showed comparable rates between Cecolin 9 (84.7%–100.0%) and a marketed HPV 9-valent vaccine (86.2%–100.0%), indicating long-term immune response persistence.

• Consistent antibody decay trends

From 7 months to three years post the first dose, both cohorts exhibited parallel antibody decay patterns. The geometric mean fold changes (GMFCs, year 3 vs. month 7) for Cecolin 9 ranged from 0.08 (95% CI: 0.07–0.09, HPV 18) to 0.17 (95% CI: 0.16–0.19, HPV 52), and for a marketed HPV 9-valent vaccine from 0.07 (95% CI: 0.07–0.08, HPV 18/45) to 0.16 (95% CI: 0.15–0.17, HPV 52).This consistency in decay kinetics further supports the stable immunopersistence of Cecolin 9, which aligns with the established long-term protective profile of the marketed HPV 9-valent vaccine.

• Reliable methodological consistency

The study used the pseudovirion-based neutralisation assay (PBNA) — a gold standard for HPV antibody detection — across both the base study andthis three-year follow-up study. This consistency ensures accurate longitudinal comparisons of immunogenicity, reinforcing the credibility of the findings.

About the Three-Year Follow-Up Head-to-Head Study (NCT06197802)

This prospective follow-up study enrolled participants from the base Phase 3 trial (NCT04782895), which randomly assigned 487 healthy Chinese women aged 18–26 years (non-pregnant, no prior HPV vaccination) to receive three doses of Cecolin 9 or a marketed HPV 9-valent vaccine (schedule: Day 0, Day 45, Month 6). The follow-up study’s primary endpoint was the comparison of plateau antibody GMCs in the per-protocol set for immunopersistence (PPS-P) — defined as participants who completed all three doses within the acceptable window, had no major protocol violations, were seronegative for the relevant HPV type at baseline, and provided valid serum samples at three years.

Blood samples were collected at three years to measure type-specific neutralising antibodies, with antibody concentrations standardised using international (HPV 16/18), China National Institutes for Food and Drug Control (NIFDC, HPV 6/33/45/52/58), or Innovax internal (HPV 11/31) reference standards. The study was conducted in accordance with the Declaration of Helsinki and Good Clinical Practice guidelines, with ethical approval from the Independent Ethics Committee of the Jiangsu Provincial Centre for Disease Control and Prevention (JSJK2023A017-02).

About Cecolin 9 (Recombinant human papillomavirus 9-valent vaccine, types 6/11/16/18/31/33/45/52/58,E. coli-produced)

Launched in China in 2025, Cecolin 9 is the world's second HPV 9-valent vaccine. This marks that China has officially become the second country, after the United States, with the independent capability to supply high-valent HPV vaccines. Building on the proven success of its predecessor, it represents the next generation in Innovax's vaccine innovation. Its development is grounded inInnovax's extensive experience in vaccine industrialization, global GMP compliance, and the establishment of robust worldwide supply chains.The state-of-the-art manufacturing facilities, designed to meet US FDA and EU EMA standards and fully compliant with China GMP, are now advancing toward WHO prequalification (PQ), reinforcing our commitment to global quality and accessibility.

About the Collaboration Between Innovax and Xiamen University

Innovax and Xiamen University have established a long-term strategic partnership in HPV vaccine research and development, combining Innovax's expertise in recombinant vaccine manufacturing with Xiamen University's strength in infectious disease research. This collaboration has led to the successful development of Cecolin (HPV bivalent vaccine, WHO-prequalified) and Cecolin 9 (HPV 9-valent vaccine), with a shared mission to advance affordable, high-quality HPV vaccines for global public health.

About Innovax

As one of the leading vaccine manufacturers in China, Xiamen Innovax Biotech Co., Ltd. (Innovax) was founded in 2005 and has been dedicated to human vaccine development, manufacturing and commercialization for nearly 20 years. As a wholly owned subsidiary of Beijing Wantai Biological Pharmacy Enterprise Co., Ltd. (Wantai BioPharm), a public listed company in China (Stock Code: 603392), Innovax's mission is to provide high-quality and affordable vaccines to improve human well-being.

Innovax has developed a unique recombinant virus-like particle (VLP) vaccine platform* based on Escherichia coli, leveraging this cutting-edge technology to successfully launched the world's first recombinant hepatitis E vaccine (Hecolin) and the world's second HPV bivalent vaccine(Cecolin). In 2025, Innovax's HPV 9-valent vaccine (Cecolin 9) has been approved in China, which is the world's second HPV 9-valent Vaccine. Innovax never stops advancing in innovation for life.

For more information, please visit Innovax's official website: https://www.innovax.cn/en/ and follow us on LinkedIn (@Xiamen Innovax Biotech Co., Ltd) and X (@Innovax).

*The technology platform is co-developed by Innovax and Xiamen University.