This study is conducted by the Sichuan Provincial Center for Disease Control and Prevention, National Institute of Diagnostics and Vaccine Development in Infectious Diseases, State Key Laboratory of Vaccines for Infectious Diseases of Xiamen University, China National Institutes for Food and Drug Control, and Xiamen Innovax Biotech Company.
Human papillomavirus (HPV) infection is a well-established cause of cervical cancer, with HPV types 16 and 18 accounting for approximately 70% of cases worldwide, while other high-risk types, including HPV 31, 33, 45, 52, and 58, contribute to an additional 20%. Beyond cervical cancer, HPV infection is also associated with multiple malignancies, such as anal, penile, vulvar, vaginal, and oropharyngeal cancers. The World Health Organization (WHO) recommends girls aged 9 to 14 years as the primary target population for HPV vaccination, as immunization prior to sexual debut provides maximal protection at the population level. In 2020, the WHO launched the Global Strategy to Accelerate the Elimination of Cervical Cancer, setting a target of achieving 90% HPV vaccination coverage among girls by the age of 15 by 2030. In China, HPV vaccines were officially incorporated into the National Immunization Program on November 10, 2025, providing strong policy support for accelerating cervical cancer prevention.
In May 2025, Cecolin ® 9 (Xiamen Innovax), the world’s second 9-valent HPV vaccine (HPV 6/11/16/18/31/33/45/52/58), received market authorization in China. This Escherichia coli (E. coli) -produced vaccine demonstrated a favorable safety profile and over 98% efficacy against persistent infections caused by the five additional oncogenic HPV types (HPV 31, 33, 45, 52, and 58), compared with Cecolin ® (the HPV 16/18 bivalent vaccine, Xiamen Innovax), in a Phase 3 clinical trial. Due to ethical constraints that preclude direct efficacy evaluation in adolescents, vaccine efficacy established in young women has been extrapolated to younger age groups through immunobridging studies.
Accordingly, the research team conducted a randomized, open-label bridging clinical trial in Yuechi County, Sichuan Province, China. A total of 1,382 healthy volunteers were enrolled, including adolescents aged 9 to 17 years and young women aged 18 to 26 years. Participants aged 9 to 17 years were stratified by age and sex and randomly assigned in a 1:1 ratio to receive either a two-dose regimen (0 and 6 months) or a three-dose regimen (0, 1, and 6 months), while participants aged 18 to 26 years received a three-dose regimen (0, 1, and 6 months). All participants were vaccinated with the 9-valent HPV vaccine. All adverse events (AEs) were monitored after each vaccination, and blood samples were collected at baseline and at month 7 to evaluate seroconversion rates and antibody levels against all nine HPV types. The results showed that, among girls aged 9 to 17 years, the immune responses elicited by the two-dose regimen were comparable to those observed in young women aged 18 to 26 years who received three doses. Both seroconversion rates and antibody titers in the adolescent two-dose group were non-inferior to those in the adult three-dose group. In addition, the vaccine demonstrated a favorable safety profile across all study groups.
Based on these findings, the National Medical Products Administration of China has approved a two-dose immunization schedule for the domestically produced 9-valent HPV vaccine in girls aged 9 to 17 years. This optimized vaccination strategy is expected to improve vaccination convenience, increase compliance, and further enhance the accessibility of HPV vaccination among adolescents.
Science Bulletin