Long-term Effectiveness and Immuno-persistence Study of a Recombinant HPV 16/18 Bivalent Vaccine in Preadolescent Girls

Inclusion Criteria:

* Participants must be at least 18 years old;
* Participants who have participated in the immunobridging clinical trial of the bivalent HPV vaccine (Unique Protocol ID:HPV-PRO-006,Identifiers: NCT02562508) and have received at least one dose of the vaccine (only applicable to the vaccine group);
* Able to understand the study procedure and have the ability to comply with the protocol requirements (e.g., collection of biological samples and regular follow-up) and sign a written informed consent form;

Exclusion Criteria:

* Participants who did not experience sexual debut;\*
* Participants with acute cervical inflammation and acute lower genital tract infection;\*
* Participants during menstruation, or have vaginal medication, sexual behavior within two days (48 hours) before the visit, which may affect gynecological examinations and specimens collection;\*
* Participants in the vaccine group have used other HPV vaccine products (including both marketed and unmarketed vaccines) after participating in the immunobridging clinical trial of the bivalent HPV vaccine (Unique Protocol ID: HPV-PRO-006, Identifiers: NCT02562508); Participants in the control group have used HPV vaccine products (including both marketed and unmarketed vaccines);
* According to the judgement of investigator, various medical, psychological, social, vocational or other factors that are not suitable for participating in the study.

  * Note: For criteria marked with an asterisk (\*), if the participant meets that exclusion criterion, it does not affect the blood sample collection.