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AIDS Vaccine Testing on Humans Halted Because of Risk


Scientists who have worked for decades to find a vaccine for the HIV and AIDS infections will meet next week at the U.S. National Institute of Health in Bethesda, Maryland to chart a future course for research. A few months ago, two human trials of a potential vaccine were halted when it appeared the drug was ineffective, and in some cases, increased the risk of getting the disease. VOA's Melinda Smith spoke Friday with Dr. Anthony Fauci, a leading international expert on HIV and AIDS.

Once again, the grim statistics: 12,000 new cases of HIV are diagnosed every day -- more than 25 million people have already died from AIDS. But the good news is that many more, approximately 40 million people, are still living with HIV.

There has been a great deal of hope pinned on the outcome of two human trials of an HIV vaccine. The STEP trial had just enrolled high-risk patients in North and South America, the Caribbean and Australia. The Phambili trial was just getting underway in South Africa. To our knowledge, none of the HIV and AIDS patients shown in our video were part of either trial.

It is standard protocol to have any human trial reviewed by an oversight committee, which monitors progress and safety. When the board assigned to monitor these trials looked at the data for the first time, it was obvious that something was not right.

"There was no indication that the vaccine was protecting against infection, and there was no indication that the vaccine was lowering the ultimate level of the virus after one person -- after a person -- got infected," says Doctor Anthony Fauci. Dr. Fauci is Director of Allergy and Infectious Diseases at the U.S. National Institutes of Health.

The review board was so concerned it recommended that both trials be stopped. Doctor Fauci says one of the most serious concerns was how the vaccine failed to protect those patients who already seemed to have an underlying immunity to a component of the HIV virus. That component is an adenovirus [adenovirus vector], found in the common cold. When those patients were given the vaccine, they had a higher risk of getting infected than those who were not yet vaccinated.

Dr. Fauci says this finding surprised him, "That was surprising. There was nothing that would have hinted that," he said.

In the meantime, what can people do who might be at risk for HIV?

Doctor Fauci says there are many drugs available to help stabilize the infection. For those who are not yet infected, some preventive steps have proven to be highly effective for what is still a highly preventable disease.

"If you are careful in your sexual contacts, you wear a condom. If you are an injection drug user, you use clean needles. If you engage in sex with someone and you don't know what their sexual history is, you use a condom. In situations, that in certain countries for example, abstinence or delaying sexual debut works (and) in some circumstances, not all -- being faithful to your partner, knowing the HIV history of your partner. Circumcision has proven to be quite effective to the tune of about 55 to 65 percent in men in situations who are heterosexually having sex with women. We're not sure about whether or not it protects among gay men," he said.

Doctor Fauci says even though the human trials were canceled, there was still valuable information that will be applied when human trials are attempted again.