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FDA Updates Guidance for Blood Samples Tested for HIV-1, HCV

NEW YORK (360Dx) – The US Food and Drug Administration has updated its guidance for testing blood samples for HIV-1 RNA and hepatitis C using nucleic acid testing technology.

The draft guidance issued on Thursday also includes recommendations for disposing patient blood samples tested for the viruses with NATs, and for managing donors of such samples. The new guidance amends recommendations that were made in 2005 by the FDA and comes amid new donor screening tests, including more sensitive tests for viral antibody, antigen for HIV-1, and nucleic acids, the agency said, noting that studies have shown that NATs have reduced the "window period," or time period when a donor is infected with a virus, but the virus cannot be detected by some technologies.

NATs have been demonstrated to reduce the window period for HIV-1 RNA by pooled sample by 11 to 15 days, compared to antibody testing and five to nine days, compared to HIV-1 p24 antigen testing, the FDA said. Meanwhile, NATS have been shown to reduce the window period for HCV by 50 to 60 day, compared to antibody testing.

Included in the new guidance are four recommended algorithms that should be used "when NAT-reactive results are obtained on individual samples or pooled samples from donors of human blood and blood components," the FDA said.

Also included are new recommendations for "donor reentry," which the agency defines as a procedure for qualifying a deferred donor as eligible for donations again. Deferred donors are barred from donating blood indefinitely due to a false-positive test result on a serologic test, followed by a negative or indeterminate supplemental test for HIV-1 or HCV antibodies.

Additionally, some donors have been deferred because of potentially false-reactive NAT results.

The new guidance includes recommendations for the reentry of deferred donors due to reactive HIV-1 NAT or HCV NAT or other tests in accordance with federal rules, the FDA said.

The guidance is for immediate implementation, the agency said.