 Totally 750 healthy girls of 9-17 years and 225 healthy young women of 18-26 years were enrolled. The subjects of 9-14 years will be stratified into 2 subset. Subjects in each subsets will be randomly assigned into the standard 0-1-6m schedule group or an alternative 0-6m group. All subjects of 15-26 years of age will receive the standard 0-1-6m schedule. Participants were actively monitored for adverse events for 1 month after each injection. Severe adverse events during the trial were followed up. Serum samples from all the subjects would be collected on day 0, 6m, 7m to evaluate the immunogenicity. 