BLOOD COMPONENT TESTING Experience of German Red Cross blood donor services with nucleic acid testing: results of screening more than 30 million blood donations for human immunodeficiency virus-1, hepatitis C virus, and hepatitis B virus Michael K. Hourfar, Christine Jork, Volkmar Schottstedt, Marijke Weber-Schehl, Veronika Brixner,* Michael P. Busch,* Geert Geusendam,* Knut Gubbe,* Christina Mahnhardt,* Uschi Mayr-Wohlfart,* Lutz Pichl,* W. Kurt Roth,* Michael Schmidt,* Erhard Seifried,* and David J. Wright* for the German Red Cross NAT Study Group BACKGROUND: The risk of transfusion-transmitted human immunodeficiency virus-1 (HIV-1), hepatitis C virus (HCV), and hepatitis B virus (HBV) infections is predominantly attributable to donations given during the early stage of infection when diagnostic tests may fail. In 1997, nucleic acid amplification technique (NAT)- testing was introduced at the German Red Cross (GRC) blood donor services to reduce this diagnostic window period (WP). STUDY DESIGN AND METHODS: A total of 31,524,571 blood donations collected from 1997 through 2005 were screened by minipool NAT, predomi- nantly with pool sizes of 96 donations. These donations cover approximately 80 percent of all the blood col- lected in Germany during that period. Based on these data, the WP risk in the GRC blood donor population was estimated by using a state-of-the-art mathematic model. RESULTS: During the observation period, 23 HCV, 7 HIV-1, and 43 HBV NAT-only–positive donations were detected. On the basis of these data and estimated pre- NAT infectious WPs, the residual risk per unit trans- fused was estimated at 1 in 10.88 million for HCV (95% confidence interval [CI], 7.51-19.72 million), 1 in 4.30 million for HIV-1 (95% CI, 2.39-21.37 million), and 1 in 360,000 for HBV (95% CI, 0.19-3.36 million). Based on observed cases of breakthrough infections, the risk of transfusion-related infections may be even lower. CONCLUSION: The risk of a blood recipient becoming infected with HCV, HIV-1, or HBV has reached an extremely low level. Introduction of individual donation testing for HCV and HIV-1 would have a marginal effect on interception of WP donations. D uring the past two to three decades, there has been a substantial decrease in the risk of transfusion-transmitted blood-borne infec- tions. This has been a result of the deve- lopment of sensitive serologic methods and the recruitment of low-risk blood donors based on imple- menting progressively more restrictive donor eligibility criteria. 1 Despite these measures, a residual risk of acquiring a transfusion-associated virus infection still exists. Fortunately, this residual risk has become ABBREVIATIONS: ChLIA = chemiluminescence assay; GRC = German Red Cross; ID = individual donation; IR-WP = incidence-rate window period; MP = minipool; WP(s) = window period(s). From the German Red Cross Baden-Württemberg–Hessen, Frankfurt, Germany; German Red Cross NSTOB, Springe, Germany; German Red Cross West, Hagen, Germany; Bavarian Red Cross, Wiesentheid, Germany; Blood Systems Research Institute, San Francisco, California; German Red Cross North, Lütjensee, Germany; German Red Cross Saxonia, Plauen, Germany; German Red Cross Mecklenburg-Western Pomerania, Neubrandenburg, Germany; German Red Cross Baden- Württemberg–Hessen, Ulm, Germany; and Westat, Rockville, Maryland. *Shared senior authorship; senior authors in alphabetical order. Address reprint requests to: M.K. Hourfar, Institute of Trans- fusion Medicine and Immunohematology, German Red Cross, Johann Wolfgang Goethe University, Sandhofstrasse 1, 60528 Frankfurt am Main, Germany; e-mail: k.hourfar@blutspende.de. Received for publication October 28, 2007; revision received January 28, 2008, and accepted January 28, 2008. doi: 10.1111/j.1537-2995.2008.01718.x TRANSFUSION 2008;48:1558-1566. 1558 TRANSFUSION Volume 48, August 2008