With just a week left until the full results of the Thai HIV vaccine trial are released, researchers are raising questions about whether the preliminary data reported last month reveal but a small and misleading glimpse of the full study results. Meanwhile, a major AIDS healthcare provider this morning (October 12) called for an independent evaluation of the data.

Human Immunodeficiency Virus Image: Wikimedia commons, NIAID

Results of the $105 million HIV vaccination study, conducted in more than 16,000 Thai volunteers, showed that the vaccine decreased the risk of HIV infection by 31% compared to placebo. A second analysis not disclosed to the public, however, may negate these findings, ScienceInsider reported last week.

At issue is the inclusion of those subjects who did not rigorously follow the protocols of the study. An analysis in which these individuals were excluded still showed a modest benefit from the vaccine, but it is no longer statistically significant, according to AIDS researchers who have supposedly seen the unreleased data.

"The [initial analysis] includes many subjects who did not receive the complete vaccine (e.g. they did not complete the protocol) and so it introduces significant noise into the analysis," Gary Nabel of the National Institutes of Health's Vaccine Research Center (VRC) explained in an email to The Scientist in response to the ScienceInsider report. "As usual, there is some truth to both sides, but my feeling is that the skeptics are overly pessimistic and fail to recognize the potential value of this study."

Although both sets of data were available to the researchers at the time of the original announcement, they chose not to report them alongside the initial analysis, Jerome Kim, a US Army scientist who was involved in the study, told the Wall Street Journal. "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." But some AIDS researchers (who preferred to remain anonymous) have suggested that the study leaders were dishonest and put a positive spin on a study with, at best, inconclusive results.

Others claim it's too early to say. "Since the data have not been formally presented in a scientific forum and are not publicly available," Barney Graham of the VRC wrote in an email to The Scientist, "I think it is premature to make any comments."


Related stories:

HIV vax testers react to Thai trial
[24th September 2009]

New wrinkle for HIV vaccine
[25th February 2009]

HIV vaccine research: crisis of faith?
[24th April 2008]

HIV vaccine trials stopped
[25th September 2007]