Infection Risk From Blood, Tissues Now Tiny
But Does Extra Blood Safety Come at Too High a Cost?
Aug. 18, 2004 -- You've now got a near-zero chance of getting HIV or hepatitis C from a blood transfusion or tissue graft, new studies show. But is this extra safety worth the extra cost?
In the early 1980s, there wasn't any way to tell whether a blood transfusion carried the deadly AIDS virus. What saved the day were antibody tests. These tests showed whether a blood donor's body was mounting an immune response against HIV. A similar test for hepatitis C virus also made blood safer.
But a dangerous window remained open. If people donated blood or tissues after getting a virus infection but before their bodies mounted an antibody attack on the virus, the tainted blood could not be detected. Now, a new technology -- nucleic acid testing -- is used to test donated blood and tissue for a virus' genetic material.
How well are these tests working? Very well, according to two reports in the Aug. 19 issue of The New England Journal of Medicine. An editorial by Jesse Goodman, MD, MPH, director of the FDA's Center for Biologics Evaluation and Research (CBER), accompanies the reports.
"I think the biggest message here is the tremendous advance in blood safety from HIV and hepatitis C virus, which are probably the two most serious illnesses that can be potentially transmitted by blood," Goodman tells WebMD. "What has happened here is in the space of just 20 years since HIV and hepatitis C virus were really infecting significant numbers of blood donors -- with pretty tragic consequences -- first we had pretty effective antibody tests, which dramatically improved blood safety, and now on top of that we have a new test. [These tests] now make the risk of getting HIV or the most serious hepatitis virus one in 2 million."
Susan L. Stramer, PhD, executive scientific officer for the American Red Cross, led a team that analyzed tests of some 37.2 million units of blood.
The result: Nucleic acid tests showed that 12 units of blood -- which passed antibody tests -- actually carried HIV. The tests detected 170 units infected with hepatitis C.
"For HIV we are talking about a rare event: One in 3 million donors is positive [on a nucleic acid test] prior to having detectable antibody," Stramer tells WebMD. "For hepatitis C virus, we tested 39 million units of blood. One in a quarter of a million was hepatitis C nucleic acid test-positive prior to appearance of detectable antibody."
D. Michael Strong, PhD, executive vice president at the Puget Sound Blood Center/Northwest Tissue Center in Seattle, led a similar study of tissues donated by 11,391 donors to five U.S. tissue banks.
They used nucleic acid tests to look for four dangerous viruses: HIV, hepatitis C virus, hepatitis B virus, and HTLV, a cancer-causing retrovirus.