Jun 1, 2011 · At 4 weeks 90% of tests would be positive, at 5 weeks 95% and at 8 weeks virtually all persons with newly acquired HIV would have positive tests. (third- and fourth-generation HIV-antibody Nov 9, 2021 · 35â45-day post exposure 50% accuracy. 95% after 6 weeks > 99% after 6 months. Second generation. 25â35 days post exposure 50% accuracy. 57 days post exposure is 99% accurate. Third generation. 22â35 days post exposure 50% accuracy. 50 days post exposure is 99% accurate. Fourth generation. The fourth generation HIV test, also called an enzyme-linked immunosorbent assay (ELISA) test, is a more complete screening that can identify acute HIV. This is the time when the virus is multiplying rapidly and you’re more likely to pass the infection. In the first few weeks after exposure to HIV, your body produces an antigen known as p24.

Because third-generation tests detect only antibodies to HIV, they cannot detect HIV infection during acute infection—the period after virus acquisition when viral protein (HIV-1 antigen) may be detectable but antibodies to HIV are not. 4 In contrast, fourth-generation HIV-1/2 testing methods can detect HIV-1 antigen as well as HIV-1 and HIV .