Full Results of AIDS Vaccine Trial Confirm Modest Benefit

Oct. 21 -- TUESDAY, Oct. 20 (HealthDay News) -- The full results of a landmark trial of an AIDS vaccine show that the shot did have limited success in protecting recipients from HIV.

But the study, published Tuesday in the New England Journal of Medicine, also suggests that this effect fades with time and may not work well for those at highest risk from HIV, such as people who engage in risky sexual practices or abuse intravenous drugs.

"Although our study provided preliminary evidence that an HIV vaccine regimen has the potential to prevent infection, it did not have the power to address two intriguing questions: vaccine efficacy may have decreased over the first year after vaccination, and vaccine efficacy may have been greater in persons at lower risk of infection," wrote the researchers who tested the vaccine on more than 16,000 young adult volunteers in Thailand.

Overall, the vaccine cut the risk of infection by almost a third, the researchers first reported in September. The full results were also described Tuesday at the AIDS Vaccine 2009 conference in Paris.

The researchers acknowledged that the protection offered by the vaccine was relatively modest and did not represent a breakthrough. But the trial results marked a significant gain in the so-far frustrating fight against AIDS, which has killed an estimated 32 million people worldwide since it struck more than a quarter century ago.

Speaking when preliminary results were first described last month, experts said the trial should give scientists important insights into HIV, the virus that causes AIDS, and how it attacks the body's immune system, with the ultimate goal of producing a more effective vaccine.

"I don't want to use a word like 'breakthrough,' but I don't think there's any doubt that this is a very important result," Dr. Anthony S. Fauci, director of the U.S. National Institute of Allergy and Infectious Diseases, one of the trial's sponsors, told The New York Times last month.