AIDS Vaccine is Still Likely...

... But not in the near future, experts say

TUESDAY, Feb. 25, 2003 (HealthDayNews) -- Depending on your perspective, this week's results of the most extensive test of an AIDS vaccine in history are encouraging, disappointing, or just plain weird.

But one thing is clear: It will be years, at the least, before anyone is routinely vaccinated against the virus that causes AIDS.

The disease has turned out to be a remarkably tenacious enemy, much harder to prevent with an injection than its cousins like smallpox, polio and chicken pox. Even now, more than two decades into the AIDS epidemic, only a single vaccine has made it to the final stages of human testing.

"To say it's five years off would be optimistic, even if everything goes well with the vaccines we're testing today," says Dr. Mark Feinberg, an AIDS vaccine researcher and professor of medicine at Emory University in Atlanta.

In fact, there are more questions this week than before.

Puzzled researchers revealed Monday that whites and Latinos who received a vaccine known as AIDSVAX weren't much less likely to become infected with the AIDS virus than their counterparts who got a placebo. (Neither group knew who was actually getting the vaccine.)

But blacks and Asians who got the vaccine were much less likely -- by as much as 78 percent -- to avoid infection.

No one knows why the vaccine appeared to work in non-Caucasian minorities. Some suspect the study numbers are misleading because the 5,400 subjects only included a few hundred non-whites. Another theory suggests that some genetic difference between the races underlies the differing reactions.

Researchers, with a possible assist from the U.S. government, plan to figure out whether the vaccine is a complete flop or a boon just for certain minority groups.

"Up until now, the data hasn't really been open to external scrutiny," Feinberg says. "There will be a fair amount of discussion and evaluation."

Meanwhile, other vaccine projects await in the pipeline. Researchers are testing the AIDSVAC vaccine on intravenous drug users in Thailand, and results of the final phase are expected later this year.

Steve Wakefield, associate director for community relations for the HIV Vaccine Trials Network, says he doesn't know of any other experimental AIDS vaccines that are headed to final testing this year. The next one isn't scheduled to reach that stage until late 2004.

The main challenge is that the usual vaccine approach -- priming the body's antibodies to fight off an infection when it arrives -- doesn't work with the AIDS virus, according to one expert. The virus is too strong and shrugs off the antibody soldiers, says Dr. Eric Goosby, chief executive officer of the Pangaea Global AIDS Foundation, an international AIDS advocacy organization.

"It's not just about developing an antibody. It's about developing an antibody that affords protection," Goosby says.

Many observers were disheartened by the findings of the AIDSVAX study. And Wall Street was particularly unimpressed. The stock price of the vaccine's manufacturer, Brisbane, Calif.-based VaxGen, fell by nearly half on Monday.

But Michael Allerton, HIV operations policy leader for Kaiser Permanente Health Plan doctors in Northern California, says there's a silver lining in the study results.

"Many people felt that a large-scale vaccine study could never be done, that the logistics and ethics would be too hard to manage," he says. But the study, he adds, proved them wrong.

"That's something that people are overlooking in the grand scheme of things," Allerton says, adding that the findings about the vaccine's effects on minorities will be studied for some time.

"It's not like all the eggs were in this basket and now they're dashed," he adds.

More information

Learn more about HIV vaccine development from the HIV Vaccine Trials Network, or the International AIDS Vaccine Initiative.

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