This is a follow-up study that 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) .The investigators 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 54 months after dose 1
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).