HIV 1 & 2 Abs/p24Ag Test

A fourth-generation blood screening test for HIV-1/2 antibodies and p24 antigen. Testing too soon after exposure can miss infection, and any reactive result requires confirmatory testing; seek urgent advice after a recent high-risk exposure because PEP is time-critical.

At a glance

• Sample: Blood
• Collection: Self-collected sample using the supplied kit
• Estimated turnaround: 1 day from laboratory receipt of a usable sample

What this test measures

HIV-1/2 antibodies and p24 antigen

A fourth-generation screen combining immune-response markers with an early viral antigen. A reactive screen is not a diagnosis and requires confirmatory testing. Testing too soon after exposure can miss infection.

How clinicians use this test

Clinicians use HIV-1/2 antibodies and p24 antigen to look for the listed infection, exposure or resistance markers at the sampled sites. Results may support diagnosis, but window periods, site selection and confirmatory testing remain important.

Is this the right test for you?

Adults seeking testing for the listed infection(s) and sampled site(s), particularly after an appropriate test window. People with symptoms or a known contact should use a sexual-health service.

Preparation and collection

Return the sample on the same day it is collected. Do not post over weekends or bank holidays.

Understanding your result

Results are usually reported as detected, not detected, reactive or non-reactive rather than simply “normal”. A reactive or detected result may need confirmation or treatment; a non-detected result does not exclude exposure during the window period or infection at a site that was not sampled.

Your results and next steps

A reactive screening result requires confirmatory testing and clinical follow-up. Do not make treatment decisions from the screening result alone.

Limitations

This test covers only the listed infections and sampled sites. Testing during a window period can miss infection, and reactive screening results may require confirmation.

When to get medical help

Do not wait for a postal result if you have symptoms, a known contact, are pregnant with a concern, or may need time-critical HIV post-exposure prophylaxis. Contact an NHS sexual-health service. Call 999 for a life-threatening emergency.