September 24, 2009
Final data from a Phase III trial showed that an experimental vaccine regimen lowered the rate of HIV infection in healthy volunteers by 31.2 percent compared to placebo, the US Army said Thursday. Eric Schoomaker, surgeon general of the US Army, which sponsored the study, said “this is the first vaccine candidate to successfully reduce the risk of HIV infection in humans.”
The study enrolled over 16 000 HIV-negative volunteers in Thailand aged 18 years to 30 years who were randomised to receive placebo or a “prime-boost” vaccination regimen consisting of sanofi-aventis’ ALVAC-HIV vCP1452 and a vaccine originally developed by VaxGen called AIDSVAX. The volunteers were administered placebo or four doses of the ALVAC vaccine and two doses of AIDSVAX over six months, and were then monitored for three years.
Results showed that HIV infections occurred in 51 of the 8197 volunteers given the vaccine regimen, compared to 74 of the 8198 volunteers who were administered placebo, a statistically significant result. Further data indicated that the vaccine regimen had no effect on the levels of HIV in the blood in those volunteers who became infected. The researchers said they do not understand exactly how the vaccine prevented infections or why it did not reduce viral load, with some calling this finding “one of the most important and intriguing.”
Michel DeWilde, senior vice president of research at Sanofi Pasteur, sanofi-aventis’ vaccine arm, called the results “the first concrete evidence…that a vaccine against HIV is eventually feasible,” however he cautioned that “further work is required to develop and test a vaccine suitable for licensure and worldwide use.” Further details from the study will be presented at a conference in October