In a good quality study, the false-positive rate of a hepatitis C enzyme-linked immunosorbent assay, or ELISA, test is around 3 percent, according to the National Center for Biotechnology Information. False-positives from antibody tests occur when antibodies are present, but the patient is not infected, according to WebMD.
ELISA tests are used to check for the presence of antibodies that suggest hepatitis C infection. Positive predictive values of 50 to 61 percent are reported for second-generation ELISA tests and a 78 percent predictive value for third-generation tests, according to the National Center for Biotechnology Information. False-positives are more likely to occur in patients with a lower risk of hepatitis C infection, for example blood donors, according to the Centers for Disease Control and Prevention.