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Unclear HIV Test Should Not Necessarily Bar Blood Donors

WebMD Health News

June 14, 2001 (Washington) -- Blood donors who have been banned from donating because of unclear tests for HIV or the hepatitis C virus should be allowed to donate again provided they undergo follow-up tests that confirm they are not infected with either of these viruses, a panel of experts convened by the FDA said on Thursday.

It is believed that these rare types of donors are not actually infected with one of the viruses. This is because even though they have tested positive for the viruses on tests designed to detect antibodies produced by the body in response to the virus, they have tested negative on more specific tests designed to detect the virus itself.

"These people are probably not infected" with the HIV or hepatitis C virus, but for whatever reason the blood tests don't reflect this, the FDA's deputy director of the division of emerging and transfusion transmitted diseases, Paul Mied, PhD, tells WebMD. Sometimes it is because the blood sample has become contaminated and in other cases the tests may simply have given false readings, he says.

The FDA was concerned about how to handle such false positive donors because current guidelines were developed before the more specific tests, which detect the RNA or genetic material of the virus, were available, Mied tells WebMD.

The ultimate decision as to whether to allow falsely positive donors to begin donating again rests with the blood banks, Mied says. But the blood banks must adhere to criteria established by the FDA.

The FDA's blood products advisory committee recommends that in the case of a false positive test for the hepatitis C virus, a second test should be done after six months because it may take this long for the person to develop detectable antibodies to the virus. In the case of HIV, the second test should be done after 56 days. Waiting until the person should have developed antibodies will help to rule out false positives.

The FDA is not bound by the recommendations of its advisory committees, but it usually follows their advice. Both the American Red Cross and the American Association of Blood Banks agreed with the committee's recommendation.

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