Researchers from the U.S. Army and Thailand announced last month they had found the first vaccine that provided some protection against HIV. But a second analysis of the $105 million study, not disclosed publicly, suggests the results may have been a fluke, according to AIDS scientists who have seen it.

The second analysis, which is considered a vital component of any vaccine study, shows the results weren't statistically significant, these scientists said. In other words, it indicates that the results could have been due to chance and that the vaccine may not be effective.

The additional data were available to the researchers on Sept. 24 when they announced the trial results, but they chose not to disclose them, said Jerome Kim, a scientist with the U.S. Army who was involved in the study. News of the second analysis was first reported on the Web site of Science magazine, but the story didn't provide specific data. Full details of the trial are to be aired at an AIDS meeting in Paris that starts Oct. 19.

The incomplete disclosure raises the question of whether the Army, the Thai government and the U.S. National Institutes of Health — which helped fund the study — rushed to give a positive spin to what may turn out to be another inconclusive AIDS-vaccine effort.

"We thought very hard about how to provide the clearest, most honest message," Kim said. "We stand by the fact that this is a vaccine with a modest protective effect." He called the trial results "complex."

Anthony Fauci, director of the National Institute of Allergy and Infectious Diseases, the part of the NIH that oversees AIDS research, declined to comment.

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