Which test is used as a confirmatory test for HIV infection?

Which test is used as a confirmatory test for HIV infection?

• A. ELISA
• B. Western Blot
• C. Rapid test
• D. HIV RNA

Answer: (B)

In HIV testing, a test used to confirm infection must be highly specific after a positive initial screen. Western blot fits this role because it detects antibodies to several distinct HIV proteins, so a true infection produces a characteristic pattern of reactivity across multiple viral antigens. This multi-antigen band pattern provides high specificity, helping to distinguish true positives from false positives that can occur with screening tests. Screening assays like ELISA are designed to be highly sensitive, catching as many true infections as possible, but they can yield false positives, which is why a confirmatory test is required. Rapid tests also function mainly as screening tools and need confirmation if reactive. HIV RNA testing, on the other hand, detects the virus itself and is used to diagnose acute infection or monitor viral load, not to confirm infection after an antibody screen.

In HIV testing, a test used to confirm infection must be highly specific after a positive initial screen. Western blot fits this role because it detects antibodies to several distinct HIV proteins, so a true infection produces a characteristic pattern of reactivity across multiple viral antigens. This multi-antigen band pattern provides high specificity, helping to distinguish true positives from false positives that can occur with screening tests.

Screening assays like ELISA are designed to be highly sensitive, catching as many true infections as possible, but they can yield false positives, which is why a confirmatory test is required. Rapid tests also function mainly as screening tools and need confirmation if reactive. HIV RNA testing, on the other hand, detects the virus itself and is used to diagnose acute infection or monitor viral load, not to confirm infection after an antibody screen.