False positive test do happen, its not isolated only to HCV testing but also on others like HIV, HBS etc...In any case, it's unwise to retest a sample with the same kind of methodology(EIA VS EIA just of different manufacutrer brand in which the degree of SENSITIVITY AND SPECIFICITY VARIES), that is why they created confirmatory test. For HCV go with RIBA, positive then yes you have the virus(but the test doesn't indicate if it is a past or present infection) if its negative, then the 1st initial testing with EIA(anti-HCV) is a false positive result. Some individuals give a physiologic false positive test, the explanation is not sure but it was thought that they have something on their blood that reacts with the reagents that causes the false positives in the absence of a viable virus. It's very ignorant to directly assume that technical error was involved. I have a friend who is false POSITIVE HIV with qualitative testing(no signs and symptoms of DSS) , negative in confirmatory TEST...we use use blood just for fun @ school. So i can attest to the FALSE thingies... SOURCES On SENSITIVITY VS SPECIFICITY = Henry's Clinical DX dont matter what edition(GOOD READ) *i assume the DR used EIA also(i might be wrong) *im still at work when im typing this so there will be grammatical errors. oh snap! blood culture Gram stain: Gram Positive Bacilli in Chains(filamentous) ! hmmmm....anthrax??? GTG BRB to edit this just my 2 cents