How Common Are False-Positive HIV Test Results After Participation in an HIV Vaccine Trial?

As HIV vaccine development efforts continue and routine HIV antibody testing becomes more common, the ability to distinguish true infection from vaccine-induced seropositivity (VISP) is increasingly important.

To determine the frequency of VISP, investigators reviewed end-of-study HIV antibody test results from 27 HIV vaccine trials. Testing was done 6 to 12 months after the last vaccination and involved three enzyme immunoassays (EIAs), followed by Western blot and, if that test yielded positive or indeterminate results, nucleic acid testing.

Of the 2176 vaccine recipients who were truly HIV-seronegative, 908 (42%) had VISP. However, the proportion varied substantially depending on the HIV vaccine construct — for example, it was 1% among tho…