Which antibody test is primarily used as the initial screening for HIV infection?

The primary antibody test used for initial screening for HIV infection is the ELISA test. This test is designed to detect antibodies to HIV in the blood, and it is highly sensitive, making it effective for screening purposes. When an individual is infected with HIV, the body typically produces antibodies within a few weeks to a few months. The ELISA test can identify these antibodies, allowing for early detection of the virus.

This test is widely used because it can process a large number of samples efficiently and provide results in a relatively short time. While other tests, such as the Western Blot, are used to confirm HIV infection following a positive ELISA result, they are not typically used for initial screening. The CD4 count, which measures immune system health, is also not a screening test for HIV but rather a marker of disease progression in individuals already diagnosed with HIV. Thus, the ELISA test stands out as the standard initial approach for screening due to its sensitivity and reliability.