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What Causes False Positives?



Is it possible to get a false positive on an ELISA and WB test? If so, what could cause such false positives? Would a tetanus shot affect the tests?


The frequency of false-positive HIV serology in a low prevalence population was 1/135,000 (0.0007%); for blood donors in Minnesota it was 6/million (0.006%).

False positive tests can occur secondary to autoantibodies ( lupus and end stage renal disease),or HIV vaccines ( most common cause-68% of 266 healthy volunteers in HIV vaccine studies had positive EIA tests and 0-44% had positive WB, depending on the antigen in the vaccine).

Tetanus vaccine does not cause  false-positive HIV test.  


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Response by:

Pamposh   Kaul, MD Pamposh Kaul, MD
Assistant Professor
College of Medicine
University of Cincinnati