Efficacy of individual nucleic acid amplification testing in reducing the risk of transfusion‐transmitted hepatitis B virus infection in Switzerland,a low‐endemic region

BACKGROUND: The risk of transfusion‐transmitted hepatitis B virus (HBV) in Switzerland by testing blood donors for hepatitis B surface antigen (HBsAg) alone has been historically estimated at 1:160,000 transfusions. The Swiss health authorities decided not to introduce mandatory antibody to hepatitis B core antigen (anti‐HBc) testing but to evaluate the investigation of HBV nucleic acid testing (NAT). STUDY DESIGN AND METHODS: Between June 2007 and February 2009, a total of 306,000 donations were screened routinely for HBsAg and HBV DNA by triplex individual‐donation (ID)‐NAT (Ultrio assay on Tigris system, Gen‐Probe/Novartis Diagnostics). ID‐NAT repeatedly reactive donors were further characterized for HBV serologic markers and viral load by quantitative polymerase chain reaction. The relative sensitivity of screening for HBsAg, anti‐HBc, and HBV DNA was assessed. The residual HBV transmission risk of NAT with or without anti‐HBc and HBsAg was retrospectively estimated in a mathematical model. RESULTS: From the 306,000 blood donations, 31 were repeatedly Ultrio test reactive and confirmed HBV infected, of which 24 (77%) and 27 (87%) were HBsAg and anti‐HBc positive, respectively. Seven HBV‐NAT yields were identified (1:44,000), two pre‐HBsAg window period (WP) donations (1:153,000) and five occult HBV infections (1:61,000). Introduction of ID‐NAT reduced the risk of HBV WP transmission in repeat donors from 1:95,000 to 1:296,000. CONCLUSIONS: Triplex NAT screening reduced the HBV WP transmission risk approximately threefold. NAT alone was more efficacious than the combined use of HBsAg and anti‐HBc. The data from this study led to the decision to introduce sensitive HBV‐NAT screening in Switzerland. Our findings may be useful in designing more efficient and cost‐effective HBV screening strategies in low‐prevalence countries.