"In 1984, the US Secretary of Health and Human Services Margaret Heckler announced at a press conference in Washington, DC, that scientists had successfully identified the virus that later became known as HIV -- and predicted that a preventative vaccine would be ready for testing in two years. Nearly four decades and 32 million deaths later, the world is still waiting for an HIV vaccine. Instead of a breakthrough, Heckler's claim was followed by the loss of much of a generation of gay men and the painful shunning of their community in Western countries. For many years, a positive diagnosis was not only a death sentence; it ensured a person would spend their final months abandoned by their communities, while doctors debated in medical journals whether HIV patients were even worth saving. The search didn't end in the 1980s. In 1997, President Bill Clinton challenged the US to come up with a vaccine within a decade. Fourteen years ago, scientists said we were still about 10 years away. The difficulties in finding a vaccine began with the very nature of HIV/AIDS itself. "Influenza is able to change itself from one year to the next so the natural infection or immunization the previous year doesn't infect you the following year. HIV does that during a single infection," explains Paul Offit, a pediatrician and infectious disease specialist who co-invented the rotavirus vaccine. "It continues to mutate in you, so it's like you're infected with a thousand different HIV strands," Offit tells CNN. "(And) while it is mutating, it's also crippling your immune system.""