The AIDS Vaccine Advocacy Coalition has published a report with information regarding the forthcoming results from a controversial Thai HIV Vaccine trial. The trial is a Phase III trial which means it tests effectiveness and safety (for more info on this go here), and the largest of its kind ever. The hugely expensive trial triggered divisive debate in the scientific community, because it involved two vaccine candidates that had minimal / no results in previous trials. Here's the basic 411 on the report's info:

In September 2009 results will be released from an AIDS vaccine phase III trial in Thailand. This test-of-concept trial is the largest AIDS vaccine trial ever conducted. The study, known as RV 144, began in 2003 and enrolled more than 16,000 HIV-negative Thai men and women between the ages of 18 and 30.

[snip]

In late September, the first announcement of data will focus on the general findings: whether there was any evidence of vaccine impact on HIV infection and/or viral load. More detailed information on the findings will be released at the annual AIDS Vaccine Conference in Paris (October 19-22). Regardless of the content of these two announcements, in-depth analysis of the findings will continue well beyond October.

As the report notes, there may be several outcomes here:

Any clinical trial may show no effect, but if there is a positive result, it will be one or both of the following:

1) The vaccine strategy reduces risk of HIV infection;
2) The vaccine strategy reduces viral load in participants who receive the experimental vaccine regimen and go on to become infected.

Even a modest indication of either of these benefits will be exciting news for the field. It would be the first time that an AIDS vaccine shows an impact on either risk of infection or viral load.

The report is available in English (PDF) and Thai (PDF).