Investigation of V520 in an HIV Vaccine Proof-of-Concept Study (V520-023)

This study will test the safety and efficacy of an investigational Human Immunodeficiency Virus (HIV) vaccine. Efficacy will be measured by either prevention of HIV infection or control of HIV viral load in subjects who become HIV infected. On September 18, 2007 the Protocol V520-023 DSMB (Data \& Safety Monitoring Board) reviewed data from a planned interim analysis. These data demonstrated that the investigational vaccine candidate was not effective, and all vaccinations in the study were halted. Participants were encouraged to continue to come to the clinic for scheduled visits and ongoing risk reduction counseling since the vaccine was not effective.