July 19, 2002 -- Two Florida residents have HIV after getting blood from an infected donor. Because the chance of this happening is about 1 in 2 million, health authorities say the U.S. blood supply remains safe.
The unidentified donor originally tested negative for the AIDS virus. He or she first gave blood shortly after the Sept. 11 terrorist attacks and then became a regular donor. A donation made in March 2002 was infected with HIV but passed testing because the donor was in the earliest stage of infection.
Blood given in May 2002 by the same donor tested positive for HIV. Officials tracked down people who received the earlier donations. Two people in the Tampa/St. Petersburg area -- identified as a young adult and as a mid-60s adult -- were infected.
"We know that this is a possibility," Paul Ness, MD, tells WebMD. "There is a small but remote risk. The risk is incredibly small compared to other things that can happen to a person who needs a blood transfusion." Ness is past president of the American Association of Blood Banks and director of transfusion medicine at Johns Hopkins University.
The problem is that when people get infected with HIV, their blood will test negative on HIV antibody tests for about 25 days. The more sophisticated nucleic acid test (NAT) shortens this window -- but for about the first 10 days after HIV infection a person has so little virus in the blood that even this test can't find it. Depending on the blood center, samples of 16 to 128 blood donations are pooled for NAT testing. Any positive result sparks an investigation.
Since 1999, all U.S. blood has been tested by both HIV antibody and HIV NAT tests. A San Antonio man was infected by donated blood in September 2001.
"When you screen blood for HIV with modern testing, there is a shorter window for HIV to get through than there used to be, but it can still happen," Ness says. "The odds are less than 1 in a million transfusions in the U.S. -- and I find it quite reassuring that the FDA estimates the odds at less than 1 in 2 million."
According to the Associated Press, the Florida blood donor was "stunned" to learn about having HIV infection. Donors must answer a lengthy series of pointed questions about HIV risk in order to give blood. There is no suggestion that the donor lied.
The AP also reports that earlier donations by the same donor went to five other people. None have HIV infections.