Antibody to hepatitis B core antigen (anti-HBc) is an antibody that generally appears close to the onset of clinical hepatitis and may persist for years or life. In the mid-1980s, U.S. blood banks voluntarily began anti-HBc screening of blood and blood components for transfusion. This test was intended as a surrogate non-specific test for hepatitis C (formerly called non-A, non-B hepatitis). In addition, studies of transfusion-associated hepatitis B prior to anti-HBc testing indicated that hepatitis B still occurred, despite the use of a sensitive test for hepatitis B surface antigen (HBsAg). On September 10, 1991, FDA issued a memorandum to all registered blood establishments providing recommendations and guidance on testing for anti-HBc, donor deferral, product labeling and quarantine. FDA recommends that blood and blood components found to be repeatedly reactive for anti-HBc should not be used for transfusion. Studies have demonstrated that transfusions of blood that is reactive for anti-HBc, but negative for Hepatitis B Surface Antigen, were associated with some cases of post-transfusion hepatitis. The numbers of transfusion recipients developing hepatitis in such circumstances are, indeed, extremely low, but FDA is committed to ensuring the safest blood supply possible. A copy of the September 10, 1991, memorandum entitled "FDA Recommendations Concerning Testing for Antibody to Hepatitis B Core Antigen (Anti-HBc)" can be obtained from CBER's web site at: http://www.fda.gov/cber/bldmem/091091.pdf. In addition, FDA recommends that donors having a repeatedly reactive test for anti-HBc on more than one occasion be indefinitely deferred until a licensed confirmatory test is available for use. At present, there is no licensed confirmatory test available. Please note that the FDA does not prevent blood banks from developing procedures more stringent than FDA's regulations and recommendations. When a blood bank incorporates a standard operating procedure, the FDA requires the blood center to specifically follow the procedures that the center has developed. Therefore, the blood bank where you donated may be following a standard operating procedure that is more rigid than current FDA recommendations. If you have had only one reactive test for anti-HBc, then you may be eligible to donate blood again, provided that all other donor suitability criteria are met and the blood center's procedures are followed. Again, the blood bank where you donated may be following a standard operating procedure that is more rigid than current FDA recommendations and, for that reason, you may be excluded from donating. The reasons for testing blood donors for anti-HBc were reviewed in January 1995, when the National Institutes of Health held a Consensus Development Conference for Infectious Disease Testing for Blood Transfusions. The panel of experts, who are not government employees, based their report on presentations by investigators working in areas relevant to the consensus questions, questions and statements from the conference attendees, and closed deliberations by the panel. The panel's recommendations included continuing testing for anti-HBc as part of the donor screening process, both to prevent hepatitis B and as a surrogate marker for HIV risk. The panel also emphasized the need to improve the specificity of screening tests for anti-HBc. FDA certainly will continue to cooperate in this effort, even potentially allowing a re-entry scheme in the future. In December 1998, a re-entry algorithm for anti-HBc was discussed at FDA's Blood Products Advisory Committee (BPAC) meeting. However, after reviewing scientific data, this panel of outside experts, which provides scientific advice to FDA, did not recommend the re-entry algorithm at that time. Individuals can be perfectly healthy, give a negative history, and yet be carriers of one or more hepatitis viruses. Unfortunately, the presence of hepatitis viruses cannot always be detected with absolute certainty by any presently available means, including history, physical exam, or laboratory tests. While some FDA requirements and recommendations may seem inconvenient or not reasonable in all situations, they actually represent measures taken to ensure that blood and blood products are as safe as possible. There is no doubt that some persons, without hepatitis or other infectious diseases, are deferred as a result of established criteria. If you would like further information about the NIH Consensus Conference, a summary statement can be obtained from the NIH Consensus Program Information Service, P.O. Box 2577, Kensington, MD 20891, phone 1-800-644-6627. More recently, on October 21, 2004, FDA discussed and obtained endorsement at our BPAC of a candidate re-entry algorithm, which is now being studied. For a detailed agenda and transcripts for this meeting, please refer to FDA's website at: http://www.fda.gov/ohrms/dockets/ac/cber04.html#BloodProducts. | 
