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.
Study Type
INTERVENTIONAL
Allocation
NON_RANDOMIZED
Purpose
PREVENTION
Masking
NONE
Enrollment
360
Administer the 9-valent HPV vaccine at month 0 and month 6 according to the immunization schedule
Administer the 9-valent HPV vaccine at month 0, 1 and month 6 according to the immunization schedule
Geometric mean concentrations (GMC) of neutralizing antibody levels against HPV types 6, 11, 16, 18, 31, 33, 45, 52, and 58;
Time frame: 7 months after the first dose (i.e., 1 month after completion of the full vaccination series)
Incidence of adverse reactions/events within 7 days after each dose of vaccination;
Time frame: Within 7 days after each dose of vaccination
Neutralizing antibody positive for HPV 6, 11, 16, 18, 31, 33, 45, 52, 58
Time frame: 7 months after the first dose (i.e., 1 month after completion of the full vaccination series)
Seroconversion rates for HPV 6, 11, 16, 18, 31, 33, 45, 52, 58
Time frame: 7 months after the first dose (i.e., 1 month after completion of the full vaccination series)
IgG binding antibody GMC for HPV 6, 11, 16, 18, 31, 33, 45, 52, 58
Time frame: 7 months after the first dose (i.e., 1 month after completion of the full vaccination series)
IgG binding antibody positivity rates for HPV 6, 11, 16, 18, 31, 33, 45, 52, 58
Time frame: 7 months after the first dose (i.e., 1 month after completion of the full vaccination series)
IgG binding antibody seroconversion rates for HPV 6, 11, 16, 18, 31, 33, 45, 52, 58
Time frame: 7 months after the first dose (i.e., 1 month after completion of the full vaccination series)
Neutralizing antibody GMC for HPV 6, 11, 16, 18, 31, 33, 45, 52, 58
Time frame: 1 Month post-dose 2 (i.e., 2 months after the first dose; 3-dose sequential & primary groups) and 1 Month post-dose 1 (i.e., 1 month after the first dose; 2-dose sequential group)
Neutralizing antibody Positivity rates for HPV 6, 11, 16, 18, 31, 33, 45, 52, 58
Time frame: 1 Month post-dose 2 (i.e., 2 months after the first dose; 3-dose sequential & primary groups) and 1 Month post-dose 1 (i.e., 1 month after the first dose; 2-dose sequential group)
Neutralizing antibody seroconversion rates for HPV 6, 11,16, 18, 31, 33, 45, 52, 58
Time frame: 1 Month post-dose 2 (3-dose sequential & primary groups) and 1 Month post-dose 1(2-dose sequential group)
IgG binding antibody GMC for HPV 6, 11, 16, 18, 31, 33, 45, 52, 58
Time frame: 1 Month post-dose 2 (i.e., 2 months after the first dose; 3-dose sequential & primary groups) and 1 Month post-dose 1 (i.e., 1 month after the first dose; 2-dose sequential group)
IgG binding antibody positivity rates for HPV 6, 11, 16, 18, 31, 33, 45, 52, 58
Time frame: 1 Month post-dose 2 (i.e., 2 months after the first dose; 3-dose sequential & primary groups) and 1 Month post-dose 1 (i.e., 1 month after the first dose; 2-dose sequential group)
IgG binding antibody seroconversion rates for HPV 6, 11, 16,18, 31, 33,45, 52, 58
Time frame: 1 Month post-dose 2 (i.e., 2 months after the first dose; 3-dose sequential & primary groups) and 1 Month post-dose 1 (i.e., 1 month after the first dose; 2-dose sequential group)
Incidence of adverse events within 30 days after each dose of vaccination
Time frame: within 30 days after each dose of vaccination
Incidence of serious adverse events throughout the study period, as well as pregnancy events and outcomes
Time frame: through study completion, an average of 7 months
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