What Is the HIV Window Period?

If you think you’ve been exposed to the virus that causes AIDS and want to take a test to find out, timing is important. After the human immunodeficiency virus (HIV) enters your body, there’s a certain amount of time that has to pass before a test can detect it. This is called the HIV window period. You need to understand your HIV window in order to get the most accurate HIV test results.

While you wait to have the test, be sure not to have unprotected sex, and don’t share needles. If you do have HIV, you could be very infectious, and you could pass it on to others.

How long do I need to wait before I test?

There’s a window period between exposure to HIV and a positive test because it takes time for your body to either build a response to the infection or for the virus to replicate enough for a test to detect it. HIV window periods can vary.

For example, if you have unprotected sex on a Friday night, and get an HIV test Monday morning, the test won’t be able to detect HIV or an immune response to HIV yet. There hasn’t been enough time for a positive result, even if the virus is in your body.

To get the earliest, most accurate result, first consider when you were exposed and whether you’re showing symptoms.

  • If you know exactly when you may have come into contact with the virus, take a test 3 months after that date. Tests 3 months after exposure should be 99% accurate.
  • If you are having symptoms of HIV, see your doctor right away. Your doctor may want to use a test that can look for the virus directly in your body.

Which test can give me results the soonest?

The period of time also differs, depending on which kind of test you take. The different types of tests include:

  • Antibody tests, which look for the antibodies -- special proteins that help fight infection -- that your body makes in reaction to an HIV infection. Most rapid tests and at-home tests are these kind. Antibody tests require the longest wait time after infection to get an accurate result. For most people -- around 97% -- this takes anywhere from 2 to 12 weeks. For some, it can take as long as 6 months.
  • Combination or fourth-generation tests, which look for both antibodies and antigens. Antigens are part of the virus itself. One antigen, p24, is detectable before your body starts making antibodies. These tests are becoming more common in the U.S. They can tell you if you have HIV a little sooner than an antibody test can.
  • Nucleic acid tests (NATs), which can detect HIV in your body the soonest after infection. The test looks for the virus in your blood. You need a certain amount of the virus in your blood before the test will detect it. This is called your viral load. You can get a negative test if your viral load is still low. A NAT can tell you if you have HIV as early as 7 to 28 days after infection. It gives the quickest result, but it’s also the most expensive. Doctors don’t typically use it unless you’re at a high risk of exposure to HIV.

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You’re more likely to have a NAT if you:

  • Are testing a baby born to a mother living with HIV
  • Took part in an HIV vaccine trial
  • Had unclear results from a previous test
  • Are having a test after known exposure but before HIV antibodies can be detected

Tell your doctor as soon as you think you’ve been exposed to HIV. Your doctor can best help you pinpoint when your HIV window is so you can take a test as soon as possible and know your status. They can also tell you whether you’ll need a follow-up test. Positive results from an antibody test typically require a follow-up test to confirm you have the virus.

The only way to know your HIV status for sure is to take a test after your window period is over. Protect yourself and others from possible exposure while you wait to have an accurate test.

WebMD Medical Reference Reviewed by Arefa Cassoobhoy, MD, MPH on June 09, 2020

Sources

SOURCES:

UCSF Center for HIV Information: “What Happens When You Get Tested for HIV?”

CDC: “Types of HIV Tests,” “Testing,” “HIV Risk Reduction Tool.”

The Well Project: “HIV Testing.”

HIV.gov: “What Can You Expect When You Go in for an HIV Test?”

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