Thai AIDS vaccine proves less effective in fresh evaluation

Full details of both the analyses have been officially made public today at the AIDS Vaccine 2009 Conference in Paris and published in the New England Journal of Medicine as well.

Initial disclosure of the experimental trial involving 16,000 volunteers, announced on Sept. 24 had shown that the vaccine reduced the risk of HIV infection by 31 percent. And the researchers claimed that the difference was statistically significant as there was only a 4 percent chance that 31 percent difference was simply a coincidence.

Second trial less convincing
Compared to the first analysis, the second one involving 12,542 volunteers showed less convincing results and it was found that the vaccine was only 26 percent better.

It was noted that the original trial excluded seven patients who were found to have HIV infections at the beginning of the trial. On the other hand, all the originally enrolled patients were included in the second analysis which produced comparatively weaker results.

The contradictory results of the second trial had been constantly criticized since they were leaked out and published on the Web site of Wall Street Journal on Oct. 12.

Mixed reviews on the twin analyses’ findings
Critics argued that "the results are weak enough that we need to be very careful about assigning too much optimism to them. . . . It seems not so likely that the vaccine really did what it was intended to do."

However, there are others who still consider the findings to be important because they believe that the results might suggest a way out to the kinds of immune responses essential to provide protection against the virus.

"This study becomes a landmark. You can put it on a map and begin to figure out where you go from here," said Col. Jerome Kim, the U.S. Army doctor who co-led the trial.

"The bottom line is that those results are real," even though they are not good enough to justify using this vaccine now, said Dr. Alan Bernstein, executive director of the Global HIV Vaccine Enterprise, an alliance of governments, AIDS scientists, the World Health Organization and funding organizations such as the Bill & Melinda Gates Foundation.