How is acute HIV diagnosed when antibody tests may be negative?

• A. Antibody test is always positive in acute infection.
• B. HIV RNA quantitative assay or p24 antigen detected during acute infection.
• C. PCR test only after years.
• D. No testing needed.

Answer: (B)

In acute HIV infection, antibody tests can be negative because seroconversion hasn’t happened yet. That’s why you look for the virus itself or its early components rather than antibodies. An HIV RNA quantitative assay directly measures viral RNA in the blood and can confirm infection within days to a couple of weeks after exposure, often before antibodies are detectable. The p24 antigen, a viral core protein, also appears in the blood early and can indicate acute infection before the antibody response. Many modern tests combine these approaches to shorten the window period, so detecting HIV RNA or p24 antigen provides the accurate diagnosis when antibody tests may still be negative. PCR-based testing is useful for early detection, not something confined to years, and choosing no testing in a suspected case would miss this early window.