There are three main types of HIV test:

The first is the HIV antibody test. This is the most commonly used, and shows whether a person has been infected with HIV. But antibodies can only be detected 1 to 3 months after infection.

The second is P24 antigen testing. It is mostly used to screen blood, but sometimes to test people as well. The P24 antigen is a protein that can be detected in blood serum soon after infection.

The third is used when a person knows that they are infected with HIV. These tests show the level of virus in the blood (viral load) and help to monitor their condition.

(China.org.cn November 30, 2004)