How Long After an HIV Exposure Should I Wait to Get an HIV Test?

Understanding the Window Period and How It Affects Testing Accuracy

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Artwork © Alan Cleaver

If a person has been exposed to HIV, there is a period by which an HIV test cannot deliver an accurate response. This is called the window period. As HIV tests are designed to detect certain markers for infection, such as antigens and antibodies, it cannot do so until enough of these proteins have been produced in response to the infection.

It can be a worrying time for person who has to sit and wait to be tested, but the good news is that newer generation tests have cut that time down dramatically.

What to Do If Your Partner's HIV Status Is Unknown

If you do not know the HIV status of a sexual partner, it was traditionally advised that you wait anywhere from 2 to 8 weeks before being test. This is because most of the assays were antibody tests, which are produced as a slower rate that antigens.

With newer combinations HIV tests, able to detect both antibodies and antigens (of both HIV-1 and HIV-2 strains), that time has dropped dramatically. Today, a lab technician using this test can make an accurate reading in about 26 days on average.

Still, there is a chance that the test may misdiagnose in the earliest (acute) stages of infection so if you believe you may have been exposed to HIV very recently, it may be best to wait a couple of weeks longer or at the very least be retested 4-6 weeks later to confirm the results, if negative.

Since some HIV tests are more accurate than others, it may be worth inquiring about which test in being used.

  While your request may be met with surprise or even disapproval, you have every right to ask if only to provide yourself greater peace of mind.

What to Do If Your Partner's HIV Status Is Known

If you believe you have been accidentally exposed to HIV, there is always one rule to follow: take action now. This is particularly true if you know your sexual partner has HIV.

In the event on an exposure, you have the opportunity to avert an infection with a 28-day course of HIV post-exposure prophylaxis (PEP).

The timing of PEP has been shown to be more effective the sooner it is started:preferably less than 6 hours after the exposure but no more than 72 hours at the latest. The decision to start PEP is based on the type of exposure (e.g., anal, vaginal, sexual assault, injecting drug use, needlestick injury), as well as the known or unknown HIV status of your sex partner.

The simple rule of thumb is that if you've been exposed by a partner whose known to be HIV positive, you should visit a doctor or emergency room as soon as possible, preferably now.

And, most importantly perhaps, do not allow embarrassment or shame discourage you from seeking either PEP or an HIV test.  In the United States, it is recommended that all Americans ages 15-65 be given a one-time HIV test as part of a routine doctor visit.


Pilcher, D.; Louie, B; Facente, S.; et al. "Performance of Rapid Point-of-Care and Laboratory Tests for Acute and Established HIV Infection in San Francisco." PLOS|One. December 12, 2013; DOI: 10.1371/journal.pone.0080629.

Smith, D.; Grohskopf, L.; Black, R., et al. "Antiretroviral Postexposure Prophylaxis After Sexual, Injection-Drug Use, or Other Nonoccupational Exposure to HIV in the United States." Morbidity and Mortality Weekly Report. January 21, 2005; 55(RR02):1-20.

Kuhar, D.; Henderson, D.; Struble, K.; et al. "Updated US Public Health Service Guidelines for the Management of Occupational Exposures to Human Immunodeficiency Virus and Recommendations for Postexposure Prophylaxis." Infection Control and Hospital Epidemiology. August 6, 2013; 34(9): 875-892.

U.S. Preventive Services Task Force (USPSTF). "Screening for HIV: U.S. Preventive Services Task Force Recommendation Statement." Rockville, Maryland; April 2013; accessed February 7, 2014.

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