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National News

Critics Contest VaxGen Claim That AIDS Vaccine Has Hope

February 25, 2003

Independent scientists argue that available data are too weak to support claims by VaxGen Inc. that its experimental AIDS vaccine protected some people against HIV infection. While company officials conceded Aidsvax overall failed to protect volunteers from HIV infection in its first major trial, they said it appeared to provide benefit in a relatively small fraction of the total population -- African Americans and some other minorities.

"Last week, no human had ever been protected from HIV infection," said VaxGen co-founder and President Donald Francis. "This week, they have." He acknowledged, however, that more work is necessary to determine whether the minority results were "a statistical fluke or a real finding." Statistical biases or other errors might account for the unexpected findings.

Dr. Anthony Fauci, director of the National Institute for Allergy and Infectious Diseases, called the minority results "quite provocative, unexplained and surprising," but he added, "The issue is: What does it mean, if anything?"

Some AIDS activists charged that the company was "obfuscating" the results. "My sense is that they're way out in front of the data," said Gregg Gonsalves of Gay Men's Health Crisis.

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VaxGen shares fell 47 percent on news of the disappointing results.

Aidsvax, which consists largely of a genetically engineered version of the HIV surface protein gp120, is intended to stimulate the production of antibodies to neutralize the virus before it can infect cells. Many scientists have long been critical of Aidsvax, arguing that because HIV mutates so quickly, a gp120 vaccine was unlikely to work. Among the 5,009 volunteers who received three injections of either Aidsvax or a placebo, the vaccine failed to produce any measurable benefit. However, among a small subgroup of minority subjects, the vaccine showed 78 percent efficacy, with less than a 2 percent likelihood the results were based on chance. Vaccinated black and Asian volunteers appeared to produce levels of HIV antibodies as much as three times higher than white or Hispanic subjects, the company said.

While major doubts exist in the scientific community, the antibody reaction among minority volunteers struck some researchers. "That was hard to put off as any kind of chance or bias," said Donald Burke, a Johns Hopkins University scientist and a former director of the US military's AIDS program. Burke reviewed the data independently.

If the results hold up, they would not necessarily mean Aidsvax works better for minority populations. Those groups might simply have been more likely to encounter HIV variants similar to those used to produce the vaccine, as opposed to a more varied, and potentially more vaccine-resistant, population of viruses in white and Hispanic groups.

Back to other CDC news for February 25, 2003

Previous Updates

Adapted from:
Wall Street Journal
02.25.03; David P. Hamilton



  
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This article was provided by CDC National Prevention Information Network. It is a part of the publication CDC HIV/Hepatitis/STD/TB Prevention News Update.
 

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