Unusual HIV-Vaccine perplexes Scientists
Scared from the escalating HIV pandemia with 25 million dead people since 1981? Here’s a flicker of hope: a HIV vaccine phase III study performed in Thailand this year is yielding promising results while reducing the infection rate with 31% effectiveness.
31 percent, that’s not rip-roaring, but at least it’s a beginning. Rather stunning, however, is the scientific approach behind this unusual trial that is performed under the code “RV 144”(a joint venture between the U.S. and Thai governments). It combines two more or less ineffective vaccines to create an effective one, Vaxgen’s AIDSVAX vaccine with Aventis Pasteur’s Alvac-HIV canarypox vector, also known as “vCP1521”.
AIDSVAX, targeting the gp120 glycoprotein that is exposed on the surface of HIV, failed in North America as well in Thailand in 2003, supplying “not a statistically significant reduction of HIV infection within the study population”.
On the other hand, the Aventis Pasteur vaccine, Alvac-HIV – a therapeutic vaccine designed to slow or halt disease progression in people who are already infected – induced just weak immunogenicity.
The current trial that cost $119 million involved 16,400 participants. 8,200 of them were given an experimental vaccine consisting of AIDSVAX / Alvac-HIV, while the remaining 8,200 were given a placebo. The participants were tested for HIV every six months. After 3 years, those given the vaccine had HIV infection rates reduced by 31% compared with those who had been given the placebo (51 newly HIV infected persons vs. 74 in the placebo group).
The US/Thai study is the only phase III trial of a HIV vaccine that currently is being performed. In addition, it’s the first successful HIV vaccine trial in history.
It’s too early to jubilate, however. These results could still be due to chance, and the whole thing has yet to undergo peer review.
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Comments
@RoaringRick: You are right. Here’s the link to the story: http://www.natap.org/2004/jan/012304_01.htm
Unless I am very much mistaken: Wasn’t there a Science paper of leading HIV researchers that denigrated this trial as “useless” and “doomed to fail”??
… think it was in 2004 or 2005? Someone who knows more?