NEW YORK--(BUSINESS WIRE)--World AIDS Vaccine Day, May 18, marks the occasion in 1997 when U.S. President Bill Clinton challenged researchers to come up with an AIDS vaccine within the following decade, stating that such a vaccine was the only way to eliminate the threat of AIDS. Twelve years later, the goal of an effective HIV vaccine remains unfulfilled, but the need for one remains urgent. AIDS is the number four killer in the world and number one in sub-Saharan Africa. Despite education and prevention campaigns, every day 7,500 people become infected with HIV. Antiretroviral drugs can prolong the lives of those who are infected, but they are not cures, and because of their cost and logistical difficulties, they reach only a minority of those who need them. And for every two individuals who go on antiretroviral treatment, five become HIV infected. As with any major viral pandemic, a vaccine remains the best hope of ending, and not just mitigating, AIDS.