Early assessment of the efficacy of a human papillomavirus type 16 L1 virus-like particle vaccine.

A post hoc analysis was performed using combined data from two Phase I tolerability/immunogenicity studies of monovalent human papillomavirus type 11 (HPV11) or HPV16 L1 virus-like particle (VLP) vaccines. The goal was to determine if the HPV16 L1 VLP vaccine protected against HPV16 infection. Vaccine or placebo was given at 0, 2 and 6 months. HPV16 infection was defined by positive polymerase chain reaction (PCR) results following vaccination. The incidence of HPV infection was observed to be 0 cases per 100 person-years at risk in the vaccine group, and 5 cases per 100 person-years at risk in the control group. These results support the institution of larger efficacy trials for HPV L1 VLP vaccines.