Investigational HIV vaccine regimen the first to show protective benefits

Combining two experimental HIV vaccines lowered the rate of HIV infection by 31.2% in 51 vaccine recipients compared with 74 patients in a placebo group, data from a phase-3 clinical trial indicated.

“This is the first HIV vaccine candidate to successfully reduce the risk of HIV infections in humans,” Lieutenant General Eric B. Schoomaker, MD, PhD, and U.S. Army Surgeon General, said in a press release.

The RV144 trial was sponsored by the U.S. Army, conducted in Thailand, and involved 16,000 adult volunteers.

The researchers randomly assigned participants to receive either primary vaccine (Alvac HIV, Sanofi Aventis) with a booster vaccine (AIDSVax B/E, Global Solutions for Infectious Diseases) or placebo during a six-month period. The two vaccines were chosen based on the most common circulating HIV subtypes in that region.

After a three-year follow-up period in which participants were screened for HIV every six months, findings showed that using a prime-boost vaccine regimen was safe and modestly effective at preventing HIV infection. However, it did not affect the viral load of volunteers who contracted HIV during the study.

More details from the trial will be presented at the AIDS Vaccine Conference in Paris this October. The U.S. Army in collaboration with the Thai Ministry of Public Health, the National Institute of Allergy and Infectious Disease and both vaccine manufacturers are working with experts in the field to determine how these findings will impact other HIV vaccine candidates.

“These results show that development of a safe and effective preventive HIV vaccine is possible,” said Colonel Nelson L. Michael, MD, PhD, director in the division of retrovirology at the Walter Reed Army Institute of Research and director of the U.S. Military HIV Research Program. “While these results are very encouraging, we recognize that further study is required to build upon these findings.”