September 14, 2011
Researchers at the AIDS Vaccine 2011 conference in Bangkok on Tuesday presented updates from an ongoing Thai trial of a vaccine characterized as "modestly effective." At the end of the initial three-and-a-half-year study, the vaccine candidate prevented HIV infection in approximately 30 percent of 16,000 volunteers compared with a placebo.
Results suggested that vaccine-conferred protection against HIV is highest at six to 12 months, and trials this fall hope to sustain or boost this immunity. But the researchers cautioned that the vaccine's formulation and the response it created are specific to the HIV type found in Thailand. It had no effect on the amount of HIV in the blood of those who became infected during the trial. And vaccination did not seem to be associated with lower amounts of virus in genital fluid.
US Army Col. Jerome Kim, one of the principal investigators, said the new findings provide clues as to how the vaccine works as well as how to conduct more focused research.
"It might be possible in the future to do vaccine trials with many fewer people much more rapidly so we could see progress occurring a lot more rapidly," Kim said.
A similar vaccine trial planned for South Africa will attempt to replicate the Thai results.