| Abstract: | Hepatitis B is caused by infection with pandemic hepatitis B virus (HBV) and has a serious impact on blood safety worldwide. Active immunization is an efficient preventive measure particularly in countries with medium and high HBV prevalence. However, as long as only some countries have started immunization programmes for their younger population and escape mutants occur, stringent donor selection and testing is presently the only approach to reduce the risk of transfusion transmitted HBV infections. Surrogate testing for alanine aminotransferase (ALT) has shown its limitations and has mostly been discontinued especially since sensitivity and specificity of hepatitis B surface antigen (HBsAg) tests have been continuously improved. However, there remains a significant risk by donations from freshly infected donors who have not yet developed detectable HBsAg levels and donations by donors with occult infection that are HBsAg‐negative but HBV DNA‐positive. Nucleic acids amplification technology (NAT) has been applied primarily to close the diagnostic window between HBV infection and HBsAg detection and has shown to be effective either in testing donor samples in mini‐pools or by individual donation (ID) testing. It has also been shown that mini‐pool NAT may not be sufficiently sensitive to identify occult chronic carriers who show very low virus concentrations in their plasma. For those chronically infected donors, highly sensitive mini‐pool NAT with specific enrichment procedures and ID NAT may be required. Anti‐HBc testing would be the most sensitive approach resulting in highest yield rates for occult carriers. However, for medium and high prevalence countries, deferral rates would be extremely high with negative effects on the blood supply. Inactivation would be a reasonable alternative but at very high costs and is presently not applicable to all blood components. Future scenarios will most probably be diverse, depending on the prevalence in a given country, its resources and the vaccination status of its population. |
