title: Transfusion-transmitted human immunodeficiency virus (HIV) from seroconverting donors is rare in England and Wales: results from HIV lookback, October 1995 through December 2008.
abstract: BACKGROUND
  Lookback is considered when human immunodeficiency virus (HIV) is detected in a repeat blood donor in case the immediately previous negative donation was donated in the infectious window period (IWP) or the assay(s) produced a false-negative result. HIV lookback investigations undertaken by NHS Blood and Transplant and the Welsh Blood Service between October 1995 and December 2008 are described.
  
  
  METHODS
  Investigations were undertaken into the previous negative donations of 113 HIV-infected donors, including retrospective testing of archive samples, tracing of components, and identification of recipients who were offered HIV testing when appropriate. Data were collated on HIV seroconverters and outcome of the lookback was summarized.
  
  
  RESULTS
  Two previous negative donations given before the introduction of minipool nucleic acid testing (MP-NAT) screening were confirmed positive by individual retrospective polymerase chain reaction (PCR) testing of the archive specimen. Red blood cell components had been transfused from both donations. One recipient died after transfusion, and the other was alive and tested HIV positive. All 23 (20%) donations previously testing negative by MP-NAT were confirmed to be PCR negative on individual testing of an archive specimen and none of the tested recipients of these donations had evidence of transfusion-transmitted HIV.
  
  
  CONCLUSIONS
  The yield of lookback was low with one positive recipient identified over 13 years of surveillance: HIV transmission occurred from a window period donation given before the introduction of MP-NAT screening and would have been detected using current testing methods. Current residual risk estimates for the United Kingdom predict that HIV lookback will be of limited benefit, as demonstrated by our data.
authors.affiliation: NHS Blood and Transplant and the Health Protection Agency Centre for Infections, London, UK. lisa.byrne2@nhsbt.nhs.uk
authors.forename: Lisa
authors.initials: L
authors.lastname: Byrne
authors.forename: Lisa J
authors.initials: LJ
authors.lastname: Brant
authors.forename: Katy
authors.initials: K
authors.lastname: Davison
authors.forename: Patricia
authors.initials: P
authors.lastname: Hewitt
mesh_terms: D001782:Blood Donors; D004739:England; D005260:Female; D006679:HIV Seropositivity / Q000635:transmission*; D006801:Humans; D008297:Male; D065227:Transfusion Reaction; D014852:Wales