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Hiv 21 days post exposure testing

Question: 

Can I test 21-25 days after an unprotected encounter?

Answer: 

Hi there! Thanks for contacting the AIDS Vancouver helpline with your HIV related questions and concerns. We are happy to help

Most test start showing accurate results at 4-6 weeks, with them being conclusive at 21-25 days. However, here is a chart with testing info:

EIA 3rd Generation

Test Name
Method
Window Period
Conditions
Enzyme Immunoassay Antibody (EIA) 3rd Generation (ELISA) Blood test that looks for antibodies. Up to 95% of infections are detectable within 4-6 weeks post exposure. Most people develop detectable antibodies in 21-25 days. Most commonly available testing method. Conclusive at 3 months post exposure.

RAPID

Test Name
Method
Window Period
Conditions
Rapid or “Point-of-Care” Blood or oral swab test that looks for antibodies. Up to 95% of infections are detectable within 4-6 weeks post exposure. Most people develop detectable antibodies in 21-25 days. The rapid test is a type of 3rd Generation test. Two forms available: finger prick blood sample or oral swab. Oral swab test is most common in the U.S. but due to false positives in Canada it is not approved and blood collection is more likely. Many places in the U.S. and abroad may charge a fee for rapid testing. Conclusive at 3 months post exposure.

POOLED RNA NAAT

Test Name
Method
Window Period
Conditions
Pooled RNA NAAT or “Early Test” Detects viral RNA in blood of people who have yet to develop detectable antibody levels. 10-12 days post exposure The pooled RNA test is often expensive and not readily available. One must be referred by a health care professional to receive this test. An antibody follow up test after 12 weeks is sometimes necessary depending on how long after the exposure the test was performed. Conclusive at 3 months post exposure.

NAAT (PCR RNA & DNA)

Test Name
Method
Window Period
Conditions
NAAT (PCR RNA & DNA) Nucleic-Acid Amplification Testing (NAAT) looks for the genetic material of HIV and tests for it with a Polymerase Chain Reaction (PCR) test. 2-3 weeks post exposure NAAT tests generally take two forms: DNA PCR and RNA PCR tests. DNA PCR NAAT tests are usually used for screening babies of HIV+ mothers. RNA PCR NAAT tests are often used to screen blood or organ donations. Both measure the viral load of a positive person’s blood. Conclusive at 3 months post exposure.

P24 Antigen

Test Name
Method
Window Period
Conditions
P24 Antigen The antigen on HIV that most commonly provokes an antibody response is the protein P24. This test looks for this protein. ONLY within first few weeks after infection. Once the body starts producing antibodies, the antigen is no longer detectable. This test is part of the 4th Generation EIA test, which most specialists agree is conclusive at 6 weeks. Official guidelines recommend re-testing at 12 weeks with an antibody test. Accuracy: see 4th Generation EIA tests.

Western Blot

Test Name
Method
Window Period
Conditions
Western Blot Immunoblot which detects HIV antibodies directed against specific HIV proteins. Interpreted according to Canadian consensus guidelines. 4-6 weeks (may take up to 8 weeks for a positive result) The Western Blot test is only used to confirm a positive test result and it considered to be the "gold standard" for confirmation of HIV infection. If test results are indeterminate, PCR NAAT Tests are usually performed to confirm an infection. Conclusive at 4-6 weeks post exposure.

4th Generation EIA

Test Name
Method
Window Period
Conditions
4th Generation EIA Blood test that looks for antibodies AND p24 protein antigens. Commonly referred to as the "combination," "combo" or "DUO" test. P24 protein is detectable immediately after infection but only for the first few weeks. The antibody (ab) test has a window period of 4-12 weeks post exposure. This test is widely available in North America. Most HIV specialists consider this test to be conclusive at 6 weeks but official HIV testing guidelines still recommend re-testing at 12 weeks for conclusive results. Conclusive at 3 months post exposure.

So as you can see, the Rapid test shows relatively accurate results at 21-25 days. This could be an option, then re-tested later on to confirm the results.

Hope this helped! Sincerely, Christina

Hello and thanks for reaching out to the AIDS Vancouver Helpline.

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