HIV Screening Test

Urgent safety information

If you think you were exposed to HIV, talk with your health care provider right away about emergency treatment called PEP (post-exposure prophylaxis). PEP may prevent an HIV infection if it is started within three days after a possible exposure. The sooner you start, the better.

Why this test may be ordered

• Routine screening: The CDC recommends everyone ages 13–64 get tested at least once as part of routine health care.
• After a possible exposure to find out if you were infected.
• If you have a higher risk for infection (e.g., had sex with someone who has HIV or whose status you don't know, shared needles or drug items, exchanged sex for money or drugs, had an STI like syphilis, or had sex with anyone who has done these things).
• If you are pregnant, because HIV can be passed to the fetus or baby, and medicines can greatly reduce that risk.
• If you have had hepatitis or tuberculosis, you should be tested at least once a year.

Preparation and collection

You don't need any special preparations. If you are getting tested in a clinic, you may want to write down any questions ahead of time.

For blood from a vein, a small needle is used to collect blood into a test tube. For blood from a finger, a lancet pricks your finger. For saliva, a swab is wiped along your gums. For urine, you may be given a cleansing wipe and container. At-home tests include rapid self-test kits (saliva) and mail-in tests (finger-prick blood).

There is very little risk to having any HIV screening test. If you have blood taken from a vein, you may have slight pain or bruising at the spot where the needle was put in, but most symptoms go away quickly.

Understanding results

Your test results will be interpreted by your health care provider. The following describes what different results may mean.

• Negative (no signs of HIV infection found): No signs of HIV were found in your sample. However, this does not always mean you don't have HIV—it may be too soon for the test to tell. If your possible exposure was 90 days ago or longer, you can be confident you don't have HIV. If it was less than 90 days ago, you will likely need another test later. Limitation: A negative result does not rule out recent infection. The time between infection and when a test can find HIV depends on your body's response and the type of test. For antibody tests, it may take up to 90 days. For antibody/antigen tests, it may take 18–90 days. For NAT tests, it may take 10–33 days. Next step: Your provider or an HIV counselor can explain your result and let you know if you need another test.
• Positive (signs of HIV infection found): Signs of HIV were found in your sample. This is a screening result and requires a follow-up test to confirm an HIV diagnosis (unless you had a NAT test). If the follow-up test is also positive, it means you have HIV. Limitation: A positive screening result does not by itself diagnose HIV. A confirmatory test is needed. If you used an at-home test, see your provider for follow-up testing. Next step: If your follow-up test is positive, it is important to start medicines called antiretroviral therapy (ART) right away, even if you still feel healthy. ART can't cure HIV, but it may lower the amount of virus in your blood enough so that a test can't find it. See your provider regularly for tests to check how your treatment is working.

• No test can find HIV immediately after infection. The window period depends on the test type and your body's response.
• A negative result does not always mean you don't have HIV—you may need a later test.
• A positive screening result requires a follow-up test to confirm an HIV diagnosis (unless a NAT test was used).
• At-home tests require careful following of instructions; results should be discussed with a provider.

What to do next

Discuss your results with your health care provider or an HIV counselor. They can explain what your result means and whether you need additional testing. If you have HIV, starting treatment early can protect your health and reduce the risk of spreading HIV to others.

• What type of HIV test did I have and what is its window period?
• Do I need a follow-up test?
• How often should I be tested based on my risk?
• What are my options for anonymous testing?

Evidence source

U.S. National Library of Medicine: HIV Screening Test