BACKGROUND: Blood donor testing for antibody to hepatitis B core antigen (anti-HBc) has been used in the United States for more than 20 years as a surrogate to prevent transmission by transfusion of non-A,non-B hepatitis, as a human immunodeficiency virus surrogate, and to reduce transmission of hepatitis B virus (HBV). Nonspecific anti-HBc assays have caused deferral of hundreds of thousands of otherwise qualified donors. A more specific anti-HBc test and a sensitive HBV DNA test should permit donor reentry after false-positive anti-HBc.

STUDY DESIGN AND METHODS: A total of 1324 otherwise eligible volunteer donors, deferred for anti-HBc reactivity on more than one occasion, were recruited from four collection facilities. They were tested using a licensed, more specific anti-HBc test, a licensed hepatitis B surface antigen (HBsAg) test, and a licensed HBV DNA assay with a 95 percent limit of detection of not more than 10 copies per mL.

RESULTS: From 11 to 32 percent of donors contacted by participating sites entered the study. Overall, 488 (37%) of the donors were negative on the more specific anti-HBc test. The proportion of putative false-positive samples varied according to the test responsible for the original deferral. A single donor, negative for the presence of anti-HBc and HBsAg, was positive for the presence of HBV DNA in one of three replicates. Repeat testing of this donor 10 months later was negative for the presence of all markers of HBV infection, and the donor had a history of HBV vaccination with documented postimmunization anti-HBs seroconversion 10 years before her anti-HBc deferral, and was considered HBV DNA false positive.

CONCLUSION: These data support reentry of donors with false-positive anti-HBc results on the relatively nonspecific assays that have been in use in the United States for more than 20 years.