The Thai trial related to HIV vaccine, showing a 31 percent protection in the case of the 16,000 HIV-infected volunteers, marks a notable advance in the two-and-a-half decade long HIV vaccine research, underscoring the possibility of an AIDS vaccine.

The study, costing $105 million, observed the volunteers over a three-year period after their enrolment in October 2003. The participants were administered a sixth-monthly combination course of four doses of ALVAC vaccine and two doses of AIDSVAX.

While the vaccines had shown little protection against HIV infection in individual trials, the combination dose reduced the chances of infection of the deadly disease in 31.2 participants, vis-à-vis those who received placebo shots.

With the HIV virus affecting over 2.7 million people per year, the findings Thai HIV vaccine trial have served as a much-needed impetus for governments and funders worldwide to make the necessary resources available for addressing the pertinent questions raised by this trial, which was conducted by the US Army and the health officials in Thailand.

Commenting on the study's results, Anthony S. Fauci - director of the National Institute of Allergy and Infectious Diseases, which largely funded the study - said: "These new findings represent an important step forward in HIV vaccine research. Additional research is needed to better understand how this vaccine regimen in the Thai study reduced the risk of HIV infection."