The primary objective of this study is to evaluate the immuno-persistence (type specific IgG antibody) of the tested vaccine administered in girls aged 9-17 years ,comparing to young healthy adults of 18-26 years who received the standard 3-dose schedule (0,1,6 months).

This is a follow-up study which is based on the bridging study of a recombinant human papillomavirus 16/18 bivalent vaccine in preadolescent girls(Unique Protocol ID:HPV-PRO-006,Identifiers: NCT02562508) .We will recruit people who have participated in bridging study before and collect their serum samples to test the seroprevalence and geometric mean concentrations of anti-HPV16 and anti-HPV18 antibody on 18 and 30 months after dose 1.

Inclusion Criteria:

1. Participants who participated in the bridging study of a recombinant human papillomavirus 16/18 bivalent vaccine in preadolescent girls (Unique Protocol ID:HPV-PRO-006-2, Identifiers: NCT02562508) and received at least one dose;
2. The legal guardian of participants under age 18 can provide identity certificate, or representative can provide authorization;
3. Participants under the age 18, able to sign or whose legal guardian agree to sign the written informed consent; or participants aged 18 and older agree to sign the written informed consent;
4. Able to comply with the requests of the study;

Exclusion Criteria:

1. Participants with coagulation dysfunction (such as coagulation factor deficiency, blood-clotting disorder, or platelet disorder) or coagulation disorders, as diagnosed by a physician after vaccination ;
2. According to the investigator's judgment, there might be some medical, psychological, social or occupational factors which might impact on the individual to obey the protocol or sign the informed consent;

Participants who participated in the bridging study (Unique Protocol ID:HPV-PRO-006-2, Identifiers: NCT02562508) and received at least one dose will be recruited.