What is the HIV test?

Due to the fact that early HIV infection often causes no symptoms, the only true way of knowing whether you are infected or not is through testing. There are a variety of laboratory testing methods available to screen blood and diagnose infection.

HIV is primarily detected by testing a person’s blood for the presence of antibodies to HIV. Antibodies are proteins that your body creates to fight infection or foreign invaders. The antibodies that your body creates are very specific to the particular infection that your body is trying to fight (i.e. HIV infection). These antibodies that are created by your body to fight HIV can be detected using what’s called the HIV antibody test. Two different types of HIV antibody test exist – the ELISA and Western Blot. Both tests are used to diagnose HIV infection. The ELISA, which stands for Enzyme Linked Immunosorbent Assay, is the most commonly used test to screen for HIV antibody because of its relatively simple methodology, high sensitivity and suitability for testing large numbers of samples. If an individual tests positive for HIV antibody using the ELISA, a second confirmatory test (usually a Western Blot) is performed. The Western Blot is perhaps the most widely accepted/used confirmatory assay for detection of antibody to HIV, and is considered the gold standard for validation of HIV antibody testing results. An individual who takes the HIV antibody test and tests positive for antibody for HIV, will be diagnosed with HIV infection.

HIV antibodies generally do not reach detectable levels until 1 to 3 months following initial infection, and may rarely take up to 6 months to be generated in quantities large enough to show up in standard blood tests for HIV antibody. This time period between becoming initially infected with HIV and the time it takes for your body to develop antibodies is called the window period. The window period of seroconversion can be anywhere from 2 weeks to 6 months after exposure to HIV. It is a very rare event that individuals will seroconvert after 6 months. If you think that you may have been exposed to HIV, you may want to get tested after the window period is over. We generally recommend that individuals get tested at least 3 months after your last risk of exposure. Waiting out the window period will ensure a more accurate test and help avoid the need to retest. Approximately 99% of HIV infected individuals will seroconvert within this 3 month window period.

Early testing (once sufficient antibody is detectable – usually after the window period), enables HIV infected individuals to receive the appropriate treatments at the time when they are most able (healthy) to fight HIV and prevent emergence of certain opportunistic infections. Another benefit of early testing is that it allows HIV infected individuals to avoid high-risk behaviors that could spread HIV to other individuals.

For more information about HIV testing in your state or HIV/AIDS in general, we encourage you to call the following:

Centers for Disease Control National AIDS Hotline: 1-800-342-2437
TTY/TDD 1-800-243-7889
Spanish Hotline: 1-800-344-7432
International: 301-217-0023
New York State residents: 1-800-541-2437