Long-term Immune Persistence of a Bivalent HPV Vaccine in Females From Study 311-HPV-1004

This long-term extension study evaluates the persistence of neutralizing antibody responses to a bivalent human papillomavirus vaccine in females who previously participated in study 311-HPV-1004 (NCT02740777). Participants belonged to one of three vaccination cohorts in the base study: adolescents who received two doses at Months 0 and 6, adolescents who received three doses at Months 0, 2, and 6, and adults who received three doses at Months 0, 2, and 6. No vaccine is administered in the extension study. Blood samples are collected at Months 84, 108, and 132 after the first dose in the base study and tested for HPV-16 and HPV-18 neutralizing antibodies using a high-throughput pseudovirus-based neutralization assay.

Inclusion Criteria: * The participant, and the participant's legal guardian when applicable, is able to understand the study information and voluntarily sign the informed consent form for the extension study. * In the investigator's judgment, the participant is able to comply with protocol requirements, including attending scheduled visits and responding to follow-up telephone contacts. * The participant was enrolled in study 311-HPV-1004 and completed blood collection at Day 0 and Months 7, 12, 24, and 36. Exclusion Criteria: * Receipt of any HPV vaccine other than the study vaccine during study 311-HPV-1004 or between completion of that study and enrollment in this extension study. * Use of an investigational or unregistered product, other than the study vaccine, during study 311-HPV-1004 or between completion of that study and enrollment in this extension study. * Seropositivity for both HPV-16 and HPV-18 antibodies at baseline in study 311-HPV-1004. * Long-term use of immunosuppressive agents or