False Positive HBsAg Result in Blood Donors Due to Administration of Three Different Recombinant DNA Hepatitis B Vaccines

Vaccines are the only effective defence mechanism against Hepatitis B. Vaccination may create "false positive" results since the immunologic agent of the vaccines and serologic marker are the same. This possibility first studied on adult subjects and no "false positive" was observed. However, studies with infants indicated otherwise. Later studies reported similar results for adults. All these studies, except one, used recombinant Engerix B vaccine. In this study, three different vaccines (i.e. Engerix B, Hepavax Gene and Gen Hevac B) were administered to 44 healthy adult subjects divided randomly into three groups. Blood samples were drawn at 1, 24h and 3 days after vaccination and tested for the presence of Hepatitis B surface antigen (HBsAg) by enzyme immunoassay (EIA). Each groups, received different vaccine, was produced one "false positive" result in blood samples drawn at 24h after vaccination. Transient antigenemia were cleared within 3 days in three subjects with "false positive" results. This study indicates that "false positive" results can be observed with different recombinant Hepatitis B vaccines. Implications of "false positive" serologic tests for blood donation and misdiagnosis are discussed.