Science

hiv vaccine, aids vaccine, RV 144
MHRP/AP
A researcher testing the “prime-boost”
combination of two vaccines during the
Thai phase III HIV Vaccine Trial.

“Modest” Success of HIV Vaccine a Significant Step for Researchers

September 27, 2009 08:00 AM
by Denis Cummings
A clinical trial found that an experimental HIV vaccine moderately reduced the risk of infection. It is the first successful large clinical trial of an HIV vaccine.

Experimental HIV Vaccine a Success

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Researchers announced Thursday that a clinical trial of an experimental HIV vaccine was a “modest” success. In the study of 16,000 people in Thailand, the vaccine—a combination of the ALVAC-HIV vaccine developed by Sanofi Pasteur and the AIDSVAX B/E vaccine developed by VaxGen, Inc.—was found to reduce the risk of HIV infection by 31 percent.

Researchers cautioned that it would take years of further development before the vaccine would be available to the public. There are still many questions about its effectiveness. Most concerning is that those who were given the vaccine and became infected did not have lower levels of the virus.

Still, the positive development, coming after a series of failures in trying to develop an HIV vaccine, is a significant step for researchers. “It provides proof of concept that a vaccine can be developed,” writes The Independent. “Researchers have a handle on the virus that they did not have before which should mean we can now look forward to further progress, though there is still a long way to go before scientists will be able to say when, or whether, a viable vaccine against HIV may be available.”

Background: HIV vaccine failures

Researchers have had a long struggle in developing treatments for HIV and AIDS since the viruses were diagnosed in the early 1980s. In 1996, the development of protease inhibitors was a breakthrough in treating AIDS, spurring a decline in AIDS deaths. The search for an HIV or AIDS vaccine has proved elusive, however.

Just two HIV vaccines had been tested in clinical trials before the RV 144 trial in Thailand, and both had failed. The first was VaxGen’s AIDSVAX, the same vaccine that was used in RV 144. It failed in two clinical trials, one in North America and one in Thailand, in 2003.

In 2007, Merck was forced to end a clinical trial of a promising vaccine after initial results indicated that it not only failed to protect against HIV, but also may have actually increased the test subjects’ susceptibility to the virus.

Following the failure of the Merck vaccine, the National Institutes of Health scaled back its development of a vaccine. In July 2008, the NIH canceled plans for a clinical trial, which at one point was set to go ahead with 8,500 volunteers.
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