Which type of HIV test is currently the most commonly used?

The most commonly used type of HIV test is the antibody test. This is primarily due to its balance of reliability, cost-effectiveness, and ease of administration. Antibody tests detect the presence of antibodies that are produced by the immune system in response to HIV infection. These tests can be performed using various biological samples, including blood and oral fluids, which increases accessibility for testing in diverse settings, including clinical facilities and community-based organizations.

Antibody tests are typically used for initial screening because they provide accurate results within a few weeks after exposure, when the body begins producing antibodies. Furthermore, many of these tests can be rapid tests, delivering results within minutes, which is crucial for prompt linkage to care and treatment.

In contrast, nucleic acid tests are generally used less frequently as they are more expensive and typically reserved for specific situations, such as confirming an acute HIV infection or monitoring viral load in patients already diagnosed. Viral load tests and CD4 tests, while critical in managing HIV treatment and progression, are not used for initial screening or diagnosis of HIV infection. These tests monitor the amount of HIV in the blood and the immune system's CD4 cell count, respectively, making them vital but not the primary tools for the initial discovery of HIV status.