This extension study aims to evaluate the long-term protection and immune response of the bivalent HPV vaccine in women aged 18-30 who participated in a previous efficacy study (311-HPV-1003). Participants will be monitored over two years, with two visits at 96 and 120 months after their initial vaccination. No additional vaccine doses will be given. Cervical samples will be obtained for ThinPrep Cytologic Testing (TCT) and HPV DNA typing. If applicable, participants meeting referral criteria for colposcopy will undergo the procedure during these visits, and tissue samples will be collected from those requiring a biopsy. Blood samples will be drawn from an immunology subset for antibody testing.The study includes data collection from multiple sites across China to assess the vaccine's long-term efficacy in preventing HPV-related cervical diseases and its durability over time.

Inclusion Criteria:

• Have the ability to understand and provide informed consent by signing the informed consent form (non-illiterate).
• Have the ability to comply with protocol requirements, such as attending scheduled visits and responding to follow-up phone calls.
• Prior enrollment in the 311-HPV-1003 study, with at least one dose of the study vaccine administered.
• At least one documented gynecological visit between 6 and 48 months during the previous 311-HPV-1003 study.
• Refrain from vaginal intercourse for 48 hours and avoid behaviors such as vaginal douching or using vaginal medications that could interfere with gynecological examinations or sample collection for 72 hours prior to each gynecological visit.

Exclusion Criteria:

• Participants who received another HPV vaccine during the prior 311-HPV-1003 study or between the end of that study and enrollment in this extension study.
• Participants diagnosed with HPV 16- or 18-related CIN2+ by an independent pathology expert panel during the prior 311-HPV-1003 study, or who were definitively diagnosed with HPV 16- or 18-related CIN2+ through external testing after the prior study ended.
• Participants who, at baseline in the 311-HPV-1003 study, tested positive for both HPV 16 and 18 antibodies, or were positive for both HPV 16 and 18 (by Cobas 4800), or whose cytology was not normal or of low-grade changes.
• Participants who are pregnant at the time of gynecological visits or within three months prior to the visit.
• Participants with any other factors deemed unsuitable for participation in the clinical trial, as determined by the investigator.

Participants in this long-term follow-up study were originally enrolled in the 311-HPV-1003 study and are drawn from multiple clinical sites across four provinces in China, including Guangxi, Hebei, Henan, and Shanxi. These participants represent a community-based sample of healthy women who received at least one dose of the Bivalent HPV vaccine or Placebo during the original study.