AIDS Vaccine has Modest Effect

Full results from the world's first successful test of an experimental AIDS vaccine confirm that it was only marginally effective and suggest that its protection against HIV infection may be more modest than was at first assumed.

Last month, researchers announced that a two-vaccine combination cut the risk of becoming infected with HIV by more than 31% in a trial of more than 16,000 volunteers in Thailand, reports the Associated Press.

The initial findings showed the vaccine's efficacy rate as statistically significant, but new analyses released on Tuesday are not as promising.

Full results, published online by the New England Journal of Medicine and presented at the 2009 AIDS Vaccine Conference in Paris, include two additional analyses that suggest the vaccine is beneficial, but not with a statistically significant efficacy rate.

Dr. Seth Berkley, head of the International AIDS Vaccine Initiative, said the vaccine combo provided a "modest effect."

"I say modest because the effect was 30%, which is a relatively low efficacy for a vaccine," Berkley told Voice of America. " You like to see a vaccine to have a public health effect a higher efficacy."

The Thailand trial was the first time an AIDS vaccine was tested mostly in heterosexuals at average risk.

While the results are not ideal, the new findings suggest that the vaccine may work better in the general population than in those at higher risk of infection, such as men who have sex with men and intravenous-drug users.

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