This is a single-center, prospective, open-label, partially randomized, matched-controlled trial designed as a cohort study. The study plans to enroll 360 healthy female participants aged 18 to 45 years, divided into three groups: a three-dose sequential group, a two-dose sequential group, and a primary immunization group, with 120 participants in each group. All participants will be stratified by two age subgroups (18-26 years and 27-45 years) to ensure demographic balance across groups.
As blinding is not feasible in this study, a prospective, open-label, partially randomized, controlled trial design is adopted. A combination of randomized and non-randomized (i.e., partially randomized) enrollment methods is used to balance study feasibility with intergroup comparability.
Participants in the three-dose sequential group and the primary immunization group will receive one dose of the nine-valent HPV vaccine at months 0, 1, and 6, while those in the two-dose sequential group will receive the nine-valent HPV vaccine at months 0 and 6. Before the second and third doses, investigators must confirm that participants do not meet the criteria for early withdrawal or for postponement of the second and third doses. After each vaccination, a 30-minute safety observation will be conducted at the vaccination site to monitor for adverse events (AEs). Subsequently, the study visit procedures will be followed, including collection of solicited AEs within 7 days post-vaccination, unsolicited AEs within 30 days, and serious AEs (SAEs) throughout the study period. Participants will also complete other scheduled study visits, including safety observations and immunogenicity blood sampling at various time points before and after vaccination.
The study aims to evaluate the immune response characteristics and safety of sequential vaccination with different doses of the nine-valent HPV vaccine (three doses at 0, 1, 6 months and two doses at 0, 6 months) in healthy female participants who have previously completed vaccination with the bivalent HPV vaccine.
1. Female volunteers, aged 18-45 years at the time of receiving the first trial vaccine dose;
2. Volunteers (and their legal guardians) are able to understand the study procedures and are capable of complying with protocol requirements (such as collecting biological samples, filling out diary cards, and attending follow-up visits on schedule), and have signed the informed consent form;
3. Adult female volunteers agree not to plan a pregnancy and to use effective contraception within 8 months after completing the first dose, or are women who have undergone tubal ligation, subtotal hysterectomy for benign lesions, or removal of benign ovarian tumors;
4. Previously completed the full three-dose schedule of XinKeNing, XiRuiShi, and WoZeHui [full three-dose schedule is defined as completing the second and third doses within 12 months after the first dose];
1. Axillary temperature > 37.0°C;
2. Positive urine pregnancy test in adult female volunteers, or being currently pregnant or breastfeeding;
3. Use of any other investigational or unregistered product (drug or vaccine) within 30 days prior to study vaccination, or planned use of other investigational or unregistered products or participation in another clinical study during the study period;
4. Long-term (continuous for more than 14 days) use of immunosuppressants or other immunomodulatory medications within 6 months prior to vaccination. Systemic administration of corticosteroid medications is excluded, while topical use (e.g., ointments, eye drops, inhalers, or nasal sprays) is permitted;