In addition to the evaluation of efficacy against HPV infection, we propose to monitor participants immunological response to vaccination, to demonstrate robust, stable, and durable antibody responses following one- and two-dose vaccination, and to enable studies to compare immune responses induced by the two vaccines, which contain different adjuvants. This effort will establish the foundation for immunobridging studies that could accelerate future vaccine development. We envision that these immunobridging studies could bridge our study to different populations and age groups and/or to next-generation vaccines that are based on the same virus-like particle technology (i.e., biosimilar vaccines).