title: Residual risk of transfusion-transmitted hepatitis B virus (HBV) infection caused by blood components derived from donors with occult HBV infection in Japan.
abstract: BACKGROUND
  Nucleic acid amplification testing (NAT) for hepatitis B virus (HBV) during blood screening has helped to prevent transfusion-transmitted HBV infection (TT-HBV) in Japan. Nevertheless, 4 to 13 TT-HBV infections arise annually.
  
  
  METHODS
  The Japanese Red Cross (JRC) analyzed repository samples of donated blood for TT-HBV that was suspected through hemovigilance. Blood donations implicated in TT-HBV infections were categorized as either window period (WP) or occult HBV infection (OBI) related. In addition, we analyzed blood from 4742 donors with low antibody to hepatitis B core antigen (anti-HBc) and antibody to hepatitis B surface antigen (anti-HBs) titers using individual-donation NAT (ID-NAT) to investigate the relationship between anti-HBc titer and proportion of viremic donors.
  
  
  RESULTS
  Introduction of a more sensitive NAT method for screening minipools of 20 donations increased the OBI detection rate from 3.9 to 15.2 per million, while also the confirmed OBI transmission rate increased from 0.67 to 1.49 per million. By contrast the WP transmission rate decreased from 0.92 to 0.46 per million. Testing repository samples of donations missed by minipools of 20 donations NAT showed that 75 and 85% of TT-HBV that arose from WP and OBI donations, respectively, would have been interdicted by ID-NAT. The ID-NAT trial revealed that 1.94% of donations with low anti-HBc and anti-HBs titers were viremic and that anti-HBc titers and the frequency of viremia did not correlate.
  
  
  CONCLUSIONS
  The JRC has elected to achieve maximal safety by discarding all units with low anti-HBc and anti-HBs titers that account for 1.3% of the total donations.
authors.affiliation: From the Blood Service Headquarters and Central Blood Institute, Japanese Red Cross, Tokyo, Japan.
authors.forename: Rikizo
authors.initials: R
authors.lastname: Taira
authors.forename: Masahiro
authors.initials: M
authors.lastname: Satake
authors.forename: Shun'ya
authors.initials: S
authors.lastname: Momose
authors.forename: Satoru
authors.initials: S
authors.lastname: Hino
authors.forename: Yoshiharu
authors.initials: Y
authors.lastname: Suzuki
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Murokawa
authors.forename: Shigeharu
authors.initials: S
authors.lastname: Uchida
authors.forename: Kenji
authors.initials: K
authors.lastname: Tadokoro
mesh_terms: D016913:Blood Component Transfusion / Q000009:adverse effects*; D001782:Blood Donors; D006509:Hepatitis B / Q000209:etiology / Q000635:transmission*; D006510:Hepatitis B Antibodies / Q000097:blood; D006801:Humans; D021141:Nucleic Acid Amplification Techniques; D012306:Risk
chemical_list: D006510:Hepatitis B Antibodies