Landmark HIV vaccine study shows some effectiveness in preventing HIV

A vaccine has reduced the risk of HIV infection in humans for the first time, in what is hailed as an historic milestone in the search for an AIDS vaccine.

A Phase III clinical trial using a combination of two earlier experimental vaccines, ALVAC HIV and AIDSVAX B/E, and involving more than 16,000 adult volunteers in Thailand over seven years, was found to lower the rate of HIV infection by more than 31%.

In the trial, 50% of the 18 to 30-year-old participants received the vaccines and 50% placebo over the course of six months and were followed for an additional three years. All were counselled on how to prevent becoming infected with HIV and received an HIV test following vaccination.

In the final analysis, 74 placebo recipients became infected with HIV compared with 51 using the vaccine, which is "statistically significant".

Colonel Nelson Michael, director, division of Retrovirology, at the Walter Reed Army Institute of Research and director of the US Military HIV Research Program (MHRP) warned that a global vaccine is still some way off and "further study is required to build upon these findings".

The trial team included the US Army, the Thai Ministry of Public Health, the National Institute of Allergy and Infectious Diseases, part of the National Institutes of Health, Sanofi Pasteur, and Global Solutions for Infectious Diseases (GSID).

Sanofi Pasteur developed ALVAC HIV and the booster vaccine, AIDSVAX B/E, was originally developed by VaxGen and is now licensed to GSID.

Mitchell Warren, executive director of the AIDS Vaccine Advocacy Coalition (AVAC), an international group that has worked towards the development of a vaccine, said: "These results move us one step further along in the marathon journey of AIDS vaccine research that continues. They also demonstrate that the scientific process is remarkable and unpredictable, and underscores the need for testing strategies in human efficacy trials.

"It will take time and resources to analyse fully, understand and validate the data, but there is little doubt that this finding will energise and redirect the AIDS vaccine field as all of us begin the hard work to translate this landmark result into true public health benefit."

Additional analysis of the data will be presented in October. It remains to be seen whether the two specific vaccine components used in this trial would be applicable to other parts of the world with diverse host genetic backgrounds and different HIV subtypes.