Guidance for Industry: Nucleic Acid Testing (NAT) for Human Immunodeficiency Virus Type 1 (HIV-1) and Hepatitis C Virus (HCV): Testing, Product Disposition, and Donor Deferral and Reentry, May 2010

This guidance provided to blood and plasma establishments contains recommendations regarding product disposition and donor management based on the results of NAT testing of individual or pooled samples for markers of HIV-1 and HCV infection on samples collected at the time of donation from donors of human blood and blood components. Also included are recommendations for re-entry of some donors after a specified waiting period based on additional test results taken from samples not associated with a blood donation. Recommendations in this guidance finalize the draft guidance issued in July 2005 under the same title.

The May 2010 guidance also supersedes the recommendations for re-entry of donors deferred because of anti-HIV-1 test results, HIV-1 p24 antigen test results, and anti-HCV test results that were provided in the FDA memoranda titled “Revised Recommendations for the Prevention of Human Immunodeficiency Virus (HIV-1) Transmission by Blood and Blood Products,” April 23, 1992; “Revised Recommendations for Testing Whole Blood, Blood Components, Source Plasma and Source Leukocytes for Antibody to Hepatitis C Virus Encoded Antigen (Anti-HCV),” Aug. 5, 1993; and “Recommendations for Donor Screening with a Licensed Test for HIV-1 Antigen,” Aug. 8, 1995.

Note: Most blood establishments have been performing HIV and HCV NAT testing on a universal basis for most of the past decade. The first NAT system for screening blood donors was licensed in 2001, followed by two more in 2002 and the most recent one in 2008. However, FDA only has recommended the use of NAT in the instance where the donor screening test for the detection of antibodies to HIV-1 or HCV was not reactive. (NAT has shown to reduce the window period for HCV and HIV-1 by 50 to 60 days and 11 to 15 days, respectively, relative to antibody testing.) This recommendation was made in the October 2004 guidance “Use of Nucleic Acid Tests on Pooled and Individual Samples from Donors of Whole Blood and Blood Components (including Source Plasma and Source Leukocytes) to Adequately and Appropriately Reduce the Risk of Transmission of HIV-1 and HCV” and is maintained in the recommendations of this guidance.

In the 2004 guidance, FDA noted that “although we recommend the use of HIV-1 NAT and HCV NAT on units that are not reactive on a donor screening test for the detection of antibodies to HIV or HCV, respectively, we do not believe that HIV-1 NAT and HCV NAT are necessary in all instances. We do not believe that a licensed HIV-1 NAT is part of the adequate and appropriate testing required under 610.40(b) for donations that are reactive on a test for the detection of antibodies to HIV-1 and are to be discarded or used in the manufacture of non-injectable products. Similarly, we do not believe that a licensed HCV NAT is part of the adequate and appropriate testing required under 610.40(a) for donations that are reactive on a donor screening test for the detection of antibodies to HCV and are to be discarded or used in the manufacture of non-inject able products. Nevertheless, you may decide to perform HIV-1 and HCV NAT in order to obtain useful information regarding the donor's infection status. This information may be useful as part of donor notification.”

At the same time, the HIV-1 NAT is the replacement test for the HIV-1 p24antigen test.

Overview

Reactive NAT minipools must be resolved, or deconstructed, to the single subpool(s) or individual sample(s) that is reactive. The reactive subpool(s) must be further resolved to determine the reactive individual sample(s). Components corresponding to the non-reactive pool samples or individual samples can be released from quarantine. When all subpools or individual samples test nonreactive, then all components may be released from quarantine; however, standard operating procedures must be followed with regard to investigation of the issues surrounding the non-resolution. The guidance document offers recommendations for laboratory control procedures to include in the standard operating procedures. When combined HIV-1/HCV NAT tests, or multiplex tests, are used, the resolution of reactive minipools to subpools and individual samples must include discriminatory NAT testing. Once a sample is identified to be reactive for HIV-1 and/or HCV NAT, the components must be quarantined and destroyed (or relabeled for further use) and the donor deferred while awaiting re-entry, if re-entry is a possibility. Lookback on repeat donors must be performed on all units donated within 12 months prior to the NAT reactive donation. Figures 1- 4 and Tables 1-4 are applicable.

Re-entry schemes for donors deferred for HIV-1 and HIV-2 are described in Figure 5 and Table 5, and re-entry for donors deferred for HCV are described in Figure 6 and Table 6. All donors are not eligible for re-entry, but the recommendations provide greater opportunities than have previously existed. Donors for whom FDA does not provide a re-entry scheme are those with the following:

• HIV-1 NAT-reactive and anti-HIV-1/2 or anti-HIV-1 or -2 repeat reactive results (regardless of blot, IFA, or p24 results).
• HIV-1 NAT-reactive and HIV-1 p24 EIA repeat reactive (regardless of other anti-HIV results).
• Anti HIV-1 or -2, or anti-HIV-1/2 repeat reactive and HIV-1 WB positive (HIV-1 NAT-non-reactive or not performed, regardless of HIV-1 p24 EIA result).
• Anti-HIV-1 or -2 or anti-HIV-1/2 repeat reactive and HIV-1 p24 EIA repeat reactive (regardless of confirmatory results for either, NAT-non-reactive, or not performed).
• HCV NAT-reactive and anti-HCV repeat reactive (regardless of HCV RIBA result).
• Anti-HCV repeat reactive and HCV RIBA positive (HCV NAT-non-reactive or not performed).

Highlights and Responses to Comments Submitted to the July 2005 Draft Guidance Document

The final recommendations contained in the May 2010 guidance address each of the comments submitted by AABB and the American Red Cross in response to the draft guidance in 2005. Key changes to the draft guidance include the following:

• The guidance contains four algorithms for use when NAT-reactive results are obtained on individual samples or pooled samples. Two of the six algorithms introduced in the draft guidance have been reduced to methods of deconstructing minipools within these four algorithms.
• Lookback period based on the NAT result is defined as 12 months prior to the NAT-reactive donation.
• Recommendations have been written to be inclusive of HIV-2 supplemental tests and NAT tests with HIV-1 group O claims when they become available.
• Donor re-entry for HIV-1 should include a group O test(NAT and antibody) when available.
• A re-entry is available for donors who are repeat-reactive on a second HIV-2 test.
• Sensitivity of the antibody test used for HCV reentry must be equal to the EIA version 3.0 or greater.
• In response to comments submitted to the draft guidance, the FDA has included unreadable western blot and immunofluorescence assays to the “groups” of donors that can be considered for re-entry.
• Persistent, unconfirmed serologic reactivity detected through testing for purposes of donor counseling during the initial eight-week (or six-month) waiting period may be followed by another waiting period at the end of which the testing may be repeated. Comments to the draft guidance noted that initial testing performed for the purpose of donor counseling often used the same lot numbers that generated the initial reactive results.
• Recommendations regarding minipools that do not resolve to an individual reactive donation or subpool have been clarified to recommend standard operating procedures that monitor the frequency of such events and investigation when the frequency exceeds the threshold defined by laboratory procedures. Comments submitted to the draft noted that a requirement to investigate each minipool that fails to resolve would be analogous to investigating each EIA reactive that does not repeat.
• HCV RIBA indeterminate donors can be retested for re-entry purposes after an additional six-month period. Comments to the draft guidance noted that this is allowed for an HIV donor with an indeterminate blot pattern that has not progressed.