HIV Screening Test

This test is a laboratory screening blood test for HIV (human immunodeficiency virus), suitable for anyone who wants clarity about their HIV status, including people with potential exposure, those starting a new relationship, or individuals who simply want routine sexual health screening. It is also used as part of antenatal care and before certain medical procedures or treatments.

The test uses a combined immunoassay to detect both HIV antibodies and the p24 viral antigen. Antibodies are produced by the immune system in response to HIV infection, while the p24 antigen is a viral protein that can be detected earlier, often before antibodies become measurable. This combined approach allows for reliable detection from around four weeks after potential exposure, with confirmation advised at three months where a recent exposure is suspected.

What the test screens for

• HIV antibodies (HIV Ab): Detects antibodies produced by the body against HIV-1 and HIV-2, indicating exposure to the virus.
• HIV p24 antigen (HIV Ag): Detects a core protein of HIV-1, allowing earlier identification of infection before antibodies appear.

A reactive screening result does not confirm a diagnosis on its own. In line with UK guidelines, any reactive sample is referred for confirmatory testing, and results are discussed with a clinician who can advise on next steps and any further tests.

Why it matters

Knowing your HIV status allows you to protect your health and that of others. Early detection means treatment can begin promptly, supporting long-term health and reducing the risk of transmission. A negative result can provide peace of mind, while a reactive result ensures you are guided quickly to confirmatory testing and specialist support.