For the first time, scientists in Germany will begin testing a vaccine against HIV, the virus that causes AIDS, on humans. The first phase of a clinical trial will start at university hospitals in Hamburg and Bonn, where 50 healthy volunteers will receive injections of the vaccine later this month. Participants don't run a risk of getting infected with the virus, according to Jan von Lunzen, who leads the team of scientists involved in the trial. Two Belgian hospitals also participate in the study, which aims to find a vaccine that can be used in developing countries. That's why later phases of the trial will take place in those countries, according to Lunzen. Should the vaccine prove to protect against infection, it will become available within seven to eight years. About 30 vaccines are currently being tested around the world.