A combination of two HIV vaccines reduced the risk of infection by almost one-third in a large trial in Thailand, the trial sponsor announced today. It is the first proof that a vaccine against HIV can protect against infection, but scientists say a lot more research will be needed before a vaccine emerges that can be given to large numbers of people.
“This is a historic day in the 26-year quest to develop an AIDS vaccine,” said Dr Alan Bernstein, executive director of the Global HIV Vaccine Enterprise.
"This is the first HIV vaccine candidate to successfully reduce the risk of HIV infection in humans. We are very excited and pleased with the outcome of this trial and congratulate all those who participated in it," said Lieutenant General Eric Schoomaker, Surgeon General, U.S. Army, the trial sponsor.
The trial, called RV 144, compared a regimen of vaccination with two products against vaccinations with a dummy, inactive substance in 16,000 adults enrolled since 2003.
Participants received an initial set of vaccinations with ALVAC, and follow-up booster vaccinations with AIDSVAX, a product previously tested in large trials without evidence of success.
The presence of AIDSVAX in the vaccination regimen was one reason why many vaccine experts had not expected the trial to show a positive result.
In the event, the prime boost combination of ALVAC(R) HIV and AIDSVAX(R) B/E lowered the rate of HIV infection by 31.2% compared with placebo.
In the final analysis, 74 placebo recipients became infected with HIV compared to 51 in the vaccine regimen arm. The efficacy result is statistically significant. The vaccine regimen had no effect on the amount of virus in the blood of volunteers who became HIV-infected during the study.
More detailed results of this study will be presented next month at the AIDS Vaccine Conference, October 19 through 22 in Paris, France.
The vaccine products used in the study will not go forward for immediate licensing. Instead, the results from the study, which was considered to be a 'proof of concept' trial, will be used to inform the design of future vaccine trials.
Collaborating partners on this study include the U.S. Army, the Thai Ministry of Public Health, the United States National Institute of Allergy and Infectious Diseases, part of the National Institutes of Health, sanofi pasteur (the developer of ALVAC), and Global Solutions for Infectious Diseases (GSID), the current developer of AIDSVAX. The collaborators are already working with external experts to determine the need for additional studies on this vaccine regimen and consider the impact of this study’s findings on other HIV vaccine candidates.
This article was first published by NAM/Aidsmap.com and is republished with permission.
Further information
See aidsmap.com's guide to The search for an AIDS vaccine for further information and background information.