HIV test: 4th-generation antibody and p24 antigen blood test

This test simultaneously screens for two markers: the HIV p24 antigen, which is a viral protein produced early in infection, and antibodies that the immune system generates in response to HIV. By detecting both, the test covers different stages of the infection timeline.

The p24 antigen is typically detectable before antibodies develop, which means this combination test can identify HIV infection during the acute phase when viral load is high and transmission risk is greatest.

HIV often causes few or no symptoms in the early phase, so a blood test can be a way to gain clarity that you cannot get from how you feel alone. Detecting a possible infection earlier may help you discuss timely care and next steps with a doctor. Knowing your status can also support informed choices for yourself and others.

A 4th-generation test can often detect infection from about 2 to 6 weeks after a possible exposure, and a reliable negative result is generally expected from about 6 weeks (in line with RIVM guidance). Testing too early may miss a recent infection, so timing matters. It can be helpful to discuss the right moment to test, and whether a repeat test is wise, with a doctor or the GGD.