False-positive hiv test results

Many False-Positive HIV Test Results for Those in AIDS Vaccine Trials

Almost half get the erroneous result, causing stigma and hampering trial enrollment, experts say

URL of this page:http://www.nlm.nih.gov/medlineplus/news/fullstory_101203.html (*this news item will not be available after 10/17/2010)
Monday, July 19, 2010
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SUNDAY, July 18 (HealthDayNews) -- Almost half of HIV-negative people who participate in clinical trials for HIV vaccines end up testing positive on routine HIV tests -- even though they're not actually infected, a new studyshows.

The reason: They underwent what experts call "vaccine-induced seropositivity/reactivity" (VISP), meaning that they possess immune system antibodies to the virus but not the virus itself.That's an important distinction, since routine HIV screening looks for virus antibodies only.

Experts pointed out that the results are not new or surprising, but simply underline the delicacies ofconducting trials into HIV/AIDS.

"You need to make sure to use other forms of testing for HIV, for example, viral load or p24 antigen, not just HIV antibodies. And people who've been in trials need toknow their antibody status by the end of the trial," said Dr. Michael Horberg, director of HIV/AIDS at Kaiser Permanente in Santa Clara, Calif. "If it is a false positive but they do not have HIVinfection, that would be very important for them to know, especially if they do repeat testing as part of good preventive health."

But a positive test can still carry stigma as well as insurancerepercussions, noted Dr. Jerome F. Levine, an infectious diseases specialist with Hackensack University Medical Center in New Jersey, adding that "trials have had trouble recruiting people for this veryreason."

The findings are simultaneously being presented Sunday at the International AIDS Conference in Vienna and published in the July 21 issue of the Journal of the American Medical Association...