National HIV Testing Day

Public health agencies in the United States recommend that everyone be tested for HIV at least once in their lifetime during adolescence or adulthood, with repeat testing based on individual risk.

The Centers for Disease Control and Prevention (CDC) advises that all people between about 13 and 64 years of age be tested at least once, and that people with ongoing risk factors, such as having multiple sex partners, having sex with partners of unknown status, or sharing injection equipment, be tested at least annually.

Sexually active gay and bisexual men and others at higher risk may benefit from testing every 3 to 6 months, especially if they are on pre‑exposure prophylaxis (PrEP).

Pregnant people are advised to have an HIV test during each pregnancy, with repeat testing in late pregnancy if they have higher risk.  

Modern HIV testing relies on three main types of tests that look for different markers of infection. Antibody tests detect the body’s antibodies to HIV and can use blood or oral fluid; most rapid tests and self‑tests fall in this category.

Antigen/antibody tests, often called fourth‑generation tests, detect both HIV antibodies and p24 antigen, a viral protein that appears earlier in infection; laboratory versions using blood from a vein are the preferred screening tests in many clinical settings.

Nucleic acid tests (NATs) detect HIV RNA (the virus’s genetic material) directly in the blood and can identify infection sooner than other tests, but are more expensive and usually reserved for specific situations, such as suspected very recent infection or indeterminate results on other tests.  

The window period is the time between acquiring HIV and the point when a specific test can reliably detect the infection. During this period a person may have HIV and be able to transmit it, yet still test negative.

For antibody‑only tests, HIV is typically detectable about 23 to 90 days after exposure; antigen/antibody laboratory tests using blood from a vein usually detect infection in roughly 18 to 45 days, while rapid antigen/antibody finger‑stick tests may take up to 90 days.

Nucleic acid tests can often detect HIV within about 10 to 33 days. Understanding the window period helps people and providers decide when to test after a potential exposure and when repeat testing is needed to rule out recent infection.  

HIV self‑tests used at home are generally reliable for detecting long‑standing HIV infection when used correctly, but they are less sensitive than laboratory tests and may miss some early infections.

The U.S. Food and Drug Administration reports that the OraQuick In‑Home HIV Test, an oral‑fluid antibody self‑test, correctly identifies about 92 percent of people who have HIV (sensitivity) and 99.98 percent of people who do not (specificity) in its studies, with performance improving when testing occurs after the window period.

A global review of self‑testing studies found similarly high sensitivity and specificity for most oral and blood‑based self‑test kits, though accuracy varied by product and user technique.

Any reactive self‑test result should be confirmed with follow‑up testing by a health care provider or laboratory before a diagnosis is made.  

A single positive HIV screening result, whether from a rapid test, laboratory test, or self‑test, is considered preliminary and must be confirmed before a diagnosis is made.

The next step is a follow‑up blood test or series of tests in a medical or laboratory setting that follow standardized diagnostic algorithms.

If confirmatory testing is also positive, the person is diagnosed with HIV and should be linked promptly to HIV medical care. Health care providers then recommend starting antiretroviral therapy, which can control the virus, preserve the immune system, and greatly reduce the risk of illness.

Public health guidance emphasizes that testing is the entry point into this “care cascade,” which includes diagnosis, linkage to care, treatment, and ongoing viral load monitoring. 

Extensive clinical evidence supports the concept known as “Undetectable = Untransmittable” (U=U). People living with HIV who take antiretroviral therapy as prescribed and maintain an undetectable viral load in their blood do not transmit HIV sexually to their partners.

Large studies of thousands of serodifferent couples have found no linked sexual transmissions when the partner with HIV had sustained viral suppression.

This finding has been endorsed by major public health bodies and is now a central message of HIV treatment as prevention. Regular HIV testing is essential for identifying infection so that treatment can be started and viral suppression, and thus U=U, can be achieved.  

Research and education campaigns consistently find that many people still overestimate the risk of casual contact and underestimate specific high‑risk behaviors.

Scientific evidence shows that HIV is transmitted through certain body fluids, notably blood, semen, vaginal fluids, rectal fluids, and breast milk, when they enter the bloodstream or mucous membranes, most often through unprotected sex, sharing needles, or from parent to child without preventive measures.

HIV is not spread by hugging, shaking hands, sharing dishes or toilets, using public swimming pools, or via mosquitoes and other insects. Studies also show that misconceptions about casual contact are strongly associated with stigma and discriminatory attitudes, which can deter people from testing and treatment, so correcting these myths is an important part of HIV education.