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Experimental AIDS Vaccine Gives Different Results Among Racial Groups - 2003-02-24

An AIDS vaccine tested for three years in North America, Europe, and Australia has proven disappointing, but not worthless.

The California drug company VaxGen says its AIDS vaccine did not show a statistically significant reduction in HIV infection in a group of 5,000 volunteers.

"Certainly we were disappointed that the vaccine did not induce a reduction in infections in all populations," says the firm's Chief Executive, Dr. Lance Gordon.

But when the test results are broken down by subgroup, the differences are dramatic.

Whites and Hispanics, the majority of the study population, did not benefit. But research scientist Michael Para says for Blacks, Asians, or other minorities who were vaccinated the infection rate was significantly lower.

"The "Black, Asian, and others" subgroup showed clear evidence of vaccine efficacy, with an efficacy of 66.8 percent," said Michael Para. "When the smaller group of just black volunteers was considered, we see a vaccine efficacy of 78.3 percent. Both of these [results] are highly significant."

The drug company says it does not know yet if racial differences or differences in the virus caused the broad variation in infection rate. It will continue to refine the data with a more thorough analysis and by continuing to collect results from study participants.

VaxGen says it could conduct further study of the groups in which it proved effective,in order to market the vaccine.

Global health officials find hope in the results, although the vaccine did not help most of those who received it. World Health Organization HIV Vaccine Coordinator Jose Esparza calls the study promising.

"African-Americans and Africans may now have a glimpse of hope, but it should also be a stimulus for other companies working on HIV vaccines to go ahead, because at least now we have some initial demonstration that protection in humans through vaccines is possible," he explained.

The vaccine tested in North America, Europe, and Australia would not necessarily work in Africa or other parts of the world, since each region has its own HIV strain. Eleven HIV subtypes have been identified.

The World Health Organization says one of the major challenges is to develop a vaccine effective against all the major strains.

VaxGen is conducting a second vaccine trial in Thailand for the subtypes prevalent in Southeast Asia, and expects to report results later this year. It is also at an early stage of developing a vaccine for the HIV strains common in sub-Saharan Africa, China, and India, which account for half of the world's infections.