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Dr. Andrew Rynne
MD
Dr. Andrew Rynne

Family Physician

Exp 50 years

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What Can Affect Pcr Test To Became False Negative ?

Good day. I have done qualitative PCR test 15 days after possible exposure and then repeated test at 30 day, both negative. 1. Do I still need to do antibody test or both PCR s are conclusive? 2. what can affect pcr test to became false negative if pcr looks for viral load which is many million copies after recent infection 2-4 weeks and pcr can detect 150 copies? Thank you
Mon, 28 Oct 2013
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Psychiatrist,  's  Response
Hi,
Though chances are less that you have false negative HIV PCR results, there is no sufficient data to show that false negative pcr turn to positive ELISA after few months. An antibody test can be done just to doubly confirm at a later date.

International HIV Testing Guidelines revolve around HIV antibody detection and suggest testing with an HIV antibody detection method (such as a 3rd Generation ELISA or a Rapid "Point-of-Care" test) at/after 12 weeks for definitive results. That said, the window period for antibody testing is 4-12 weeks, with 95% of infections being detected within 4-6 weeks.

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What Can Affect Pcr Test To Became False Negative ?

Hi, Though chances are less that you have false negative HIV PCR results, there is no sufficient data to show that false negative pcr turn to positive ELISA after few months. An antibody test can be done just to doubly confirm at a later date. International HIV Testing Guidelines revolve around HIV antibody detection and suggest testing with an HIV antibody detection method (such as a 3rd Generation ELISA or a Rapid Point-of-Care test) at/after 12 weeks for definitive results. That said, the window period for antibody testing is 4-12 weeks, with 95% of infections being detected within 4-6 weeks. Hope this helps