A large clinical trial of a vaccine against AIDS, for the first time, gave positive results. But once the researchers questioned the relevance of the data, indicating that the vaccine offered only modest protection against HIV infection.
The controversial trial, conducted with more than 16,000 volunteers in Thailand over the past six years, tested the effectiveness of two vaccines against AIDS used together as a double blow. The researchers randomly assigned an equal number of participants who were at average risk of becoming infected with HIV to receive either the vaccines or a saline placebo. At the end of the study in June, 51 of the vaccinees were infected within 3 years after their last shot, compared to 74 people in the placebo group. The p value, which indicates whether the results are due to chance was less than 0.039, just below the "meaning" break widely accepted but arbitrary 0.05. Surprisingly, the vaccine does not appear to suppress levels of the virus in 51 people who were infected. No serious adverse events were observed in both groups.
Many researchers vaccine against AIDS had predicted that the study would be a failure, and its sponsors are delighted with the effectiveness, marginal though it may be. "Although the level of protection was modest, we believe that the study is a major scientific advance," said Col. Jerome Kim, head of HIV vaccines produced for the US Army, who collaborated with the Thai Ministry Health to conduct the efficacy trial. "We were all very excited by the results." The US military and Thai officials will announce the results of the trial, the largest ever held for a vaccine against AIDS (see table on other vaccine trials against AIDS after the jump) at conference now press in Thailand and the United States.
Several critics long study, which cost $ 105 million, were stunned and wary when they learned the results.
"Wow. Wow," said the researcher vaccine against AIDS Ronald Desrosiers, director of the New England Primate Research Center in Southborough, Massachusetts. "Looking at the numbers, it is disappointing to me. But I want to stay close and get a bunch of people to do the analysis and see if the protective effect held under further review." Dennis Burton, an immunologist at the Scripps research Institute in San Diego, California, had a similar reaction. "It's very early days," said Burton. "People should be extremely careful now." In an editorial published in Science shortly after the start of the trial (January 16, 04, p. 316), Desrosiers, Burton, and 20 other prominent AIDS researchers have argued that the study should never have been started.
skepticism about the study comes from poor results of previous vaccine, tested separately and together, in smaller clinical trials. In the just-ended trial, individuals vaccinated first received "seed" of a preparation, manufactured by Sanofi Pasteur in Lyon, France, which contained a canarypox virus that researchers had designed to contain HIV genes. A "booster" shot contained a recombinant form of the HIV surface protein, gp0, made by VaxGen, a company in South San Francisco, California. VaxGen has sold the rights to develop the product to Global Solutions for Infectious Diseases after the product failed in efficacy trials when tested alone. Both vaccines were based on HIV strains circulating in Thailand.
Although the data are positive, US military researchers point out that many discussions have yet to take place before someone decides to use vaccines with such modest efficacy. Yet Colonel Nelson Michael, director of the Research Program on HIV military of the United States, said he hopes the results will help researchers finally unravel the immune responses that correlate with protection, and then build on this information to design more effective vaccines. "These results tell us that at least walking on this road is worth it," said Michael. "From the scientific point of view, I pray this will begin to inform our arguments. So much of what people have said, in the absence of clinical success as it is theology. We finally have an argument that will be impregnated with data rather than theories. "
Michael and his colleagues plan to present the data in more detail at a vaccine against AIDS conference in Paris on 19-22 October. "That will definitely stir up the field," said Desrosiers
table credit :. AIDS Vaccine Advocacy Coalition
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