Use of supplemental anti-HBc testing of donors showing non-discriminating reactive results in multiplex nucleic acid testing

Background and Objectives The Korean Red Cross began nucleic acid amplification testing (NAT) for HIV and HCV in February 2005, and added HBV NAT beginning in June 2012. The current NAT system utilizes a multiplex assay for simultaneous detection of HBV DNA, HCV RNA and HIV-1 RNA. For samples that are reactive in the multiplex assay, we do specific tests for each virus. However, there have been cases of non-discriminated reactive (NDR) results which appear to be the result of non-specific reactions or cross-contamination, although some cases are considered to arise from the presence of low levels of HBV DNA due to occult hepatitis B infection. Materials and Methods We examined the incidence of NDR results in previous donations of some NAT-reactive donors. Additionally, for those donors with NDR results, we performed an HBV core antibody (anti-HBc) assay. Results From November 2015 to March 2016, there were 408 NAT-reactive donors. Of these, nineteen HBV NAT-reactive donors showed a history of NDR results in the past donations. Seven donors showed NDR results more than once. Of 771 NDR donors, 362 (47·0%) were anti-HBc reactive. Conclusion The NDR donors had a substantially higher rate of anti-HBc reactivity than other blood donors indicating that some with anti-HBc reactivity represent donors with occult HBV. Therefore, the incorporation of an anti-HBc testing for NDR donors could improve blood safety testing for the Korean Red Cross.