False-positive serologic tests for human T-cell lymphotropic virus type I among blood donors following influenza vaccination, 1992.

From October 31 through December 15, 1991, 10 blood donors to the American Red Cross Blood Services, Badger Region (ARCBS), were found to have false-positive screening enzyme-linked immunosorbent assays (ELISAs) for antibodies to two or more of the following viruses: human immunodeficiency virus type 1 (HIV-1), human T-cell lymphotrophic virus type 1 (HTLV-I), and hepatitis C virus (HCV). An investigation by the Division of Health, Wisconsin Department of Health and Social Services (WDOH), and the ARCBS indicated that the risk for false-positive reactivity was associated with antecedent receipt of influenza vaccine formulated for the 1991-92 season. In March 1992, the ARCBS began use of newly available ELISAs for anti-HIV (HIVAB, HIV-1/HIV-2 (rDNA) EIA [Abbott Laboratories, Abbott Park, Illinois]) and anti-HCV (HCV 2.0 ELISA [Ortho Diagnostic Systems, Raritan, New Jersey]), while continuing to test with the ELISA for anti-HTLV-I [HTLV-I ELISA (Abbott Laboratories) used in 1991. From January 1 through October 13, 1992, the ARCBS identified 19 blood donors with repeatedly reactive ELISAs for HTLV-I. However, from October 14 through November 10, 15 false-positive ELISAs for HTLV-I were reported by the ARCBS to the WDOH. As a result of this increase, the ARCBS conducted a case-control study to assess the relation between influenza vaccination and testing positive for HTLV-I. This report summarizes the results of the study.