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Safeguarding Blood Against HIV: When Is Enough Enough?

The U.S. blood supply now is screened for common bloodborne viruses with both antigen and antibody tests, but the "window" period between infection and seroconversion means that newly infected blood donors still theoretically can infect recipients.

To estimate trends for this risk, researchers surveyed units donated by 1.9 million volunteers in 5 U.S. cities from 1991 through 1996. Among units discarded because of infection, hepatitis C was found most commonly in those of first-time donors, with a prevalence that fell from 0.63 percent to 0.40 percent during the study; both prevalence and incidence of HIV were low (approximately 0.02 percent and 1.6 per 100,000 person-years, respectively) and declined over the study period, despite a rising population prevalence of HIV (suggesting that predonation behavioral screening has been helpful in minimizing potentially risky donations). Hepatitis B had the highest incidence among repeat donors (10 per 100,000 person-years).

Could testing batched aliquots of blood with ultrasensitive nucleic acid amplification techniques (NAT) for HIV reduce risk for transmission still further? Plasma from a newly HIV-infected donor in Singapore whose blood products caused infection in 2 recipients had an HIV RNA level of less than 40 copies per mL. NAT detected virus in the undiluted plasma, but not in some diluted samples, indicating that batched screening, which has been proposed as one way of further safeguarding the blood supply, may not offer reliable results.

Comment: The blood supply is safer now than ever. Is it safe enough? An editorialist points out that the tiny risks for viral infection from transfused blood (now estimated at 1 in 677,000 units for HIV, 1 in 103,000 for hepatitis C, and 1 in 63,000 for hepatitis B) means that blood is as safe as, or safer than, many commonly prescribed medications, even without further viral screens.

— A Zuger

Published in Journal Watch General Medicine July 28, 2000

Citation(s):

Glynn SA et al. Trends in incidence and prevalence of major transfusion-transmissible viral infections in US blood donors, 1991 to 1996. JAMA 2000 Jul 12 284 229-235.

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Ling AE et al. Failure of routine HIV-1 tests in a case involving transmission with preseroconversion blood components during the infectious window period. JAMA 2000 Jul 12 284 210-214.

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Klein HG. Will blood transfusion ever be safe enough? JAMA 2000 Jul 12 284 238-240.

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