title: Multiple unconfirmed-reactive screening tests for viral antibodies among blood donors.
abstract: BACKGROUND
  In December 1991, the United States Food and Drug Administration received reports of blood donations with unconfirmed reactivity on screening tests for antibodies to human immunodeficiency virus, human T-lymphotropic virus type I, and hepatitis C virus (HCV). Of 91 donors with these test results, 57 (63%) reported a recent influenza vaccination.
  
  
  METHODS
  To determine the extent of unconfirmed reactivity, the time at which it began, and its association or nonassociation with specific manufacturers' tests, a nationwide survey of blood centers was conducted. A case-donation was defined as a blood donation that was repeatedly reactive, but not confirmed positive, on at least two of the three tests from May 1990 through December 1991.
  
  
  RESULTS
  Among 14 million donations screened by 110 centers, 582 case-donations were identified. An increase in case-donations was evident in the fall of 1990 (2.8/100,000 donations). In 1991, rates increased from 0.9 per 100,000 donations in the first quarter to 1.3, 3.2, and 19.7 in subsequent quarters. A significantly higher rate of case-donations was observed among donations tested with one of the two available anti-HCV screening tests (8.0 vs. 1.2/100,000 donations; risk ratio = 6.8; 95% CI = 5.4-8.5).
  
  
  CONCLUSIONS
  Although unconfirmed reactivity on multiple screening tests appeared to be seasonal, its documentation prior to the availability of influenza vaccine in 1991 and higher rates among donations tested with one manufacturer's anti-HCV test indicated that test-specific factors were also involved.
authors.affiliation: Division of Viral and Rickettsial Diseases, Centers for Disease Control and Prevention, Atlanta, Georgia.
authors.forename: J
authors.initials: J
authors.lastname: Buffington
authors.forename: C N
authors.initials: CN
authors.lastname: Shapiro
authors.forename: R C
authors.initials: RC
authors.lastname: Holman
authors.forename: T W
authors.initials: TW
authors.lastname: Strine
authors.forename: B J
authors.initials: BJ
authors.lastname: Grossman
authors.forename: A E
authors.initials: AE
authors.lastname: Williams
authors.forename: M J
authors.initials: MJ
authors.lastname: Alter
authors.forename: L B
authors.initials: LB
authors.lastname: Schonberger
mesh_terms: D000914:Antibodies, Viral / Q000097:blood*; D001782:Blood Donors; D003140:Communicable Disease Control / Q000379:methods*; D005189:False Positive Reactions; D006678:HIV / Q000276:immunology; D016174:Hepacivirus / Q000276:immunology; D015368:Human T-lymphotropic virus 1 / Q000276:immunology; D006801:Humans; D007124:Immunoenzyme Techniques; D007252:Influenza Vaccines / Q000008:administration & dosage; D008403:Mass Screening; D011795:Surveys and Questionnaires; D014611:Vaccination
chemical_list: D000914:Antibodies, Viral; D007252:Influenza Vaccines