RV144, an experimental HIV vaccine at the center of the largest human AIDS trial to date, is the first to show a significant result in HIV prevention.

The study, a joint effort between vaccine patent-holders and U.S. and Thai governmental agencies, involved more than 16,000 Thai volunteers -- half who received six doses of the vaccine in 2006, half who received a placebo.

Though RV144 was shown to be only 31% effective against infection, the trial results left researchers stunned and renewed hope that a vaccine against the deadly disease is still possible.

In a brief interview, spoke about the findings with Mitchell Warren, executive director of AIDS Vaccine Advocacy Coalition. How does the RV144 study differ from past studies that showed no significant evidence of protection against HIV infection?

Mitchell Warren: Previous efficacy studies looked at either antibody response or a cellular [CD4- or CD8-cell] response. This trial was the first large-scale efficacy trial to try a prime-boost combination vaccine, one meant to stimulate both cellular and antibody responses.
What’s the bottom line of this study?

It’s the first time we’ve had any significant positive result for a vaccine. We’ve always fundamentally believed that a vaccine is possible, but the clues have always come from various animal studies, elite controllers [people who are infected with HIV but never develop symptoms of AIDS], and highly exposed uninfected individuals.

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