Results of this second analysis, published in Science magazine’s Web site and The Wall Street Journal, suggest that the supporting data is not statistically significant.
The initial results of the clinical trial released on Sept. 24 had indicated that the vaccine reduced the chance of HIV
infection by 31 percent, but a follow-up "per protocol" analysis showed that there is 16 percent chance that the study results were just a coincidence.
Researchers’ take
Experts who have seen the data informed that the secondary analysis excluded patients who did not follow the experimental regimen. When that was done, less convincing results were shown and it was found that the vaccine was only 26 percent better, they said.
In the wake of this development, the researchers have subsequently been criticized for incomplete disclosure.
Dr. Anthony S. Fauci, director of one of the National Institutes of Health, which financed the trial, admitted that different analyses of the data could show a weaker effect. However, he maintained that the analysis released on Sept. 24, which included every participant in the trial, was “the gold standard”.
The initial trial
In the first experimental trial, 16,000 volunteers were chosen from a cross-section of the Thai young adult population, aged 18 to 30, and not just high-risk groups like the sex workers.
Half of the volunteers were given six doses of two vaccines in 2006 and half were given placebo shots, informed Col. Jerome H. Kim, a physician and manager of the army’s HIV vaccine program.
The medical condition of the volunteers was followed for three years. Out of those who got placebos, 74 became infected, as compared to only 51 of those that were given the vaccine shots.
The researchers found that the vaccine seemed to work 31 percent better than the placebo shots. They said that the difference was statistically significant as there was only a 4 percent chance that 31 percent difference was simply a coincidence.
It was for the first time that a vaccine had shown signs of protection against the disease that has killed more than 25 million people worldwide. Therefore, the scientists hoped that the results of the clinical trial may have "important implications for the design of future HIV vaccines".
It is expected that the full details of the second trial will be made public on Oct. 20 at a meeting in Europe, and the researchers are writing a paper to be submitted to the New England Journal of Medicine.
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