The vaccine regimen consisted of two separate vaccines. The first was a killed canarypox virus containing pieces of AID and the second was an HIV surface protein that plays a key role in infection. This regimen was based on HIV strains that commonly circulate in Thailand. The main goal of the vaccine regimen was to train the immune system to attack HIV, so that if a vaccinated individual were exposed to the virus, his or her immune system would successfully fight off the infection. A secondary goal was to determine if the vaccine regimen could reduce the amount of HIV in the blood of vaccinated study participants who later became infected with the virus.