or the first time ever, an investigational vaccine regimen has shown some efficacy, albeit modest, in preventing HIV acquisition. The prime-boost regimen involves a combination of two previously tested vaccines — ALVAC-HIV and AIDSVAX B/E — that were designed to protect against clades B and E. ALVAC-HIV consists of three genetically engineered HIV genes (env, gag, and pro) and a live-canarypox vector, whereas AIDSVAX B/E consists of genetically engineered gp120. The regimen was tested in a phase III trial in Thailand among more than 16,000 adults aged 18 to 30 at average risk for HIV infection. Half received two doses of ALVAC-HIV alone, followed by two doses of both ALVAC-HIV and AIDSVAX B/E, over a 6-month period; the other half received placebos. For the next 3 years, all participants underwent HIV testing and behavioral counseling every 6 months.During follow-up, 51 of the 8197 people in the vaccine group acquired HIV infection, compared with 74 of the 8198 in the placebo group. The difference — which represents an absolute reduction of 0.3% and a relative reduction of 31% — was statistically significant. Vaccination did not appear to reduce viral load among those who became infected. The vaccine regimen was safe and well tolerated, and there was no evidence that participants increased high-risk behavior during the trial. Source: Journal Watch, 9/28/2009. Ref: McNeil DG Jr. For first time, AIDS vaccine shows some success.New York Times . Sep 24 , 2009. (http://www.nytimes.com/2009/09/25/health/research/25aids.html) & HIV vaccine study first to show some effectiveness in preventing HIV [press release]. Rockville, MD: U.S. Military HIV Research Program; Sep 24 , 2009. (https://www01.hjf.org/apps/internet/hivnewscenter.nsf/phase3pressrelease) & U.S. Military HIV Research Program. FAQs: Frequently asked questions regarding the RV144 phase III HIV vaccine trial. Sep 24 , 2009.https://www01.hjf.org/apps/internet/hivnewscenter.nsf/phase3resources/$FILE/RV144-FAQs-20090924.pdf). Comments: A great early and promising step although the information we have so far is scarse and not from peer-reviewed journal or even a medical conference. I think we should withhold judgement until information are made available for scrutiny. BA