Anonymous on November 21, 2011

What is the window period of HIV?

I’ve heard there’s a window period for HIV, but I don’t know what that means. Can you help?

answered by Lisa Oldson, MD on November 21, 2011

You’ve asked a great question. The window period for HIV can help you understand when to test for HIV after you’ve had an encounter that could have exposed you to the virus.

A window period refers to the segment of time from when someone is infected with HIV to when it will show up on a test. Why is there a lag? It takes a little time for enough of the virus or enough antibodies to be made in the body before they can be detected with HIV tests.

We offer two tests that can detect an HIV infection. The HIV Early Detection test looks for HIV in the blood. It is possible that the test can pick up HIV as early as 6 days after exposure, but to be on the safe-side our medical experts encourage people to wait 21 days after unprotected sex or sharing intravenous needles. 

The HIV Antibody test looks for antibodies to HIV...and because it takes a little longer for antibodies to develop in the body, the testing window is about 4-6 weeks. Keep in mind that the Centers for Disease Control and Prevention have stated that most people newly infected with HIV will have detectable antibodies by 25 days after exposure and that 97% will have detectable antibodies after 3 months. 

To sum up, the recommended testing window period for HIV is 21 days for the HIV Early Detection test and about 4-6 weeks for the HIV Antibody test. 

I’m glad you’re asking these smart questions about HIV testing. 

You can learn more about windows for HIV and other STDs, in our STD Testing Windows guide. Thanks for your question and good luck in your health.

Lisa Oldson, MD

Dr. Oldson is Medical Director of the Analyte Physicians Group. She is on staff at Northwestern Memorial Hospital, as well as Clinical Instructor at the Feinberg School of Medicine, Northwestern University. Her areas of expertise include STDs (with a particular clinical emphasis on herpes), women's health, preventive medicine, diabetes, obesity and weight management, and mood and anxiety disorders. Dr. Oldson was educated at Rush Medical College and completed her residency at Rush-Presbyterian-St. Luke's Medical Center in Chicago, IL.

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