In an early-morning announcement today, researchers reported that an experimental HIV (human immunodeficiency virus) vaccine effectively reduced the number of people who contracted the virus by nearly a third. Tested in a U.S.-sponsored trial that involved more than 16,000 volunteers in Thailand, the vaccine was administered in six injected doses starting in 2006 to half of the group, and the other half received a placebo. Seventy-four people in the placebo group had contracted HIV by the end of the trial, whereas only 51 of the vaccinated group tested positive.* The injections consisted of two vaccines that had proven unsuccessful on their own: Sanofi-Aventis SA's ALVAC and VaxGen Inc.'s AIDSVAX.
The results came as a surprise to HIV-vaccine skeptics in the AIDS (acquired immunodeficiency syndrome) research field, whose numbers have increased after years of failed vaccine trials. "It's safe to say that the scientific community is caught off-guard," Mitchell Warren, director of the AIDS Vaccine Advocacy Coalition, told Bloomberg News. Before the announcement, Marie-Paule Kieny, director of the World Health Organization's Initiative for Vaccine Research, told the news service: "I don't think that there is a lot of expectation that the efficacy of this vaccine will be very high." A 2007 clinical trial of a vaccine made by Merck was stopped when researchers found that, in fact, more people who received the active vaccine (49) than the placebo (33) had contracted HIV.
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