What is the first test commonly used to screen for HIV?

The ELISA test is the first test commonly used to screen for HIV due to its effectiveness in detecting antibodies to the virus. This test is relatively simple, cost-effective, and allows for high-throughput testing, making it the standard initial screening method for HIV infection.

The ELISA test looks for antibodies produced by the immune system in response to HIV, which can typically be detected within a few weeks to months after infection. Since many individuals might not exhibit symptoms early on, early detection through antibodies is crucial for diagnosis.

Other tests, such as the rapid test, are also used for screening but are usually employed as confirmatory tests or in settings where immediate results are necessary. While PCR tests are important for measuring the viral load in patients known to be infected, they are not used for initial screening. The Western blot is primarily a confirmatory test rather than a screening tool. Hence, the ELISA test serves as the foundational screening tool for HIV in the public health context.