This study aims to assess the immunogenicity and safety of a sequential 2vhpv to 9vhpv immunization schedule in girls aged 9-14 years

A post-marketing study is being conducted in Zhejiang Province to evaluate the immunogenicity and safety of a sequential 2vhpv to 9vhpv immunization schedule in girls aged 9-14 years. The study plans to recruit 300 healthy participants, who will be randomly assigned in a 1:1:1 ratio to three groups. In Experimental Group A, participants will receive one dose of the bivalent HPV vaccine followed six months later by two doses of the 9-valent HPV vaccine. In Experimental Group B, participants will receive one dose of the 9-valent HPV vaccine six months after a single dose of the bivalent HPV vaccine. The control group will receive two doses of the 9-valent HPV vaccine at a six-month interval. Venous blood samples will be collected before the first dose, before and one month after each dose of the 9-valent vaccine, and at 12 and 24 months after full immunization to assess HPV vaccine-type-specific neutralizing antibodies.

In addition, 100 healthy girls will be enrolled as an external control group receiving two doses of the bivalent vaccine, with blood samples collected before each dose and at 1, 12, and 24 months post-vaccination to assess HPV vaccine-type-specific neutralizing antibodies.

Furthermore, 6 participants from each of the following groups who received the Wantai or Merck Sharp & Dohme HPV vaccine were selected as the cellular immune subgroup: Experimental Group A (2vhpv[Cecolin]-9vhpv[Cecolin 9]- 9vhpv[Cecolin 9] and 2vhpv[Cecolin]-9vhpv[Gardasil 9]-9vhpv[Gardasil 9]), Experimental Group B (2vhpv[Cecolin]-9vhpv[Cecolin 9] and 2vhpv[Cecolin] -9vhpv[Gardasil 9]), control group (9vhpv[Cecolin 9]-9vhpv[Cecolin 9] and 9vhpv[Gardasil 9]-9vhpv[Gardasil 9]), and external control group (2vhpv[Cecolin] -2vhpv[Cecolin]). For the cellular immune subgroup of Experimental Group A, venous blood samples were collected before the second dose (9-valent vaccine), at 7 days and 1 month after the second dose, and at 1 month after the third dose (9-valent vaccine) to isolate plasma and PBMCs. For the cellular immune subgroups of Experimental Group B, the control group, and the external control group, venous blood samples were collected before the second dose, at 7days and 1 month after the second dose to isolate plasma and PBMCs for analysis of antigen-specific cellular response characteristics.

Inclusion Criteria

• Have not received any HPV vaccine products.
• Girls aged 9 to 14 years.
• Reside permanently at the research site. Both the participant and her legal guardian have voluntarily agreed to participate, have signed the informed consent form, understand and agree to comply with the study protocol, and are able to complete all scheduled blood collections and follow-up visits.

Exclusion Criteria

• Suspected or confirmed fever (≥38.5°C) within 72 hours prior to enrollment, or axillary temperature >37.0°C on the day of enrollment.
• HIV infection or other immunocompromising conditions.
• Presence of acute illness or being in the acute phase of a chronic disease.
• History of severe allergic reactions to any component of the study vaccine or to previous vaccinations.
• Contraindications to intramuscular injection, such as thrombocytopenia, coagulation disorders, or current anticoagulant therapy.
• Receipt of non-live vaccines within 14 days or live attenuated vaccines within 28 days prior to HPV vaccination in this study.
• Receipt of blood or blood-derived products within 3 months prior to enrollment, or planned use within 6 months from the first vaccination to completion of the full vaccination schedule.
• Any disease or condition deemed by the investigator to place the participant at unacceptable risk, prevent adherence to study requirements, or interfere with the assessment of vaccine responses.