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third generation antibody test is sufficient?

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I would be grateful for your kind support to clear my few queries. I had a high risk exposure, receptive anal/oral sex with a Chinese guy of unknown HIV status. At 14th day of my exposure, I did HIV 1 RNA PCR QUANTITATIVE test which was "Target Not Detected". At 28th day, I also did HIV 1/2 & P24 COMBO test which is NON REACTIVE. But, my concern is when I calculated very carefully, I found that the exact timing when my blood was drawn for COMBO test was 27 Days + 19 Hours after exposure which means it is not exactly at 28th day mark which is less by 4-5 hours. So, my doubts are: 1). Is there a much difference practically on HIV COMBO P24 test done at 27th day as in my case; it is not exactly 28 days or 28 days post exposure ? 2). I am thinking to repeat HIV COMBO P24 test coming sunday as it will be 6th week of exposure. Is it really necessary or third generation antibody test is sufficient in 6th week for reliable results? 3). How likely is my chances of turning positive later on ?

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replied June 13th, 2014
Welcome to e health forum.

Specifically answering to your questions -

1. No, a few hours deviation would not alter the test results. As long as the test was done after 3 weeks (for the 4th Generation ELISA test), the results can be considered valid.

2. It would be better to do the 4th Generation test, rather than the 3rd Gen ELISA test.

3. Based on the history given, The risk of HIV infection occuring after a single exposure (anal receptive intercourse) would be about 0.08 % per encounter. Chances of infection by this route increase if the act was unprotected and there was ejaculation inside you, the guy was HIV positive with high Viral loads, and there was any form of bleeding inside. The probability of you having a positive test result can hence be considered very low.

I hope this helps.
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