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Date of last update: 10/12/2017.

Forum Name: AIDS

Question: Would a PEP med increase the likelihood of a false negative?

 trey3025 - Fri Jan 09, 2009 10:00 am

I'm currently taking a 30-day supply of Truvada as a post exposure prophylactic after a high-risk exposure to HIV. I've read that even in cases where PEPs don't inhibit the transmission of HIV that they can greatly reduce the viral load during the acute phase. If this is the case, would the fact that I'm taking Truvada increase the likelihood that the HIV antibody test at the 3-week post-exposure mark would return a false negative? In other words, would a newly infected person taking Truvada produce detectable amounts of antibodies at a later date than someone who was infected but wasn't taking Truvada? I'm wondering if I should assign much credit to the results of the 3-week antibody test.
 John Kenyon, CNA - Sun Feb 08, 2009 11:02 pm

User avatar Hello -

While I am unaware of any studies which specificlaly address your question, it does stand to reason that antibodies would become reduced as the viral load is reduced (assuming the virus is even present), so it does become somewhat of a puzzle. Since HIV takes a good six weeks to develop significant antibodies anyway, the early test is essentially a baseline test, so not too much can be taken away from it unless one has already been infected for some time.

The follow up test should be far more telling, so long as the PEP has been discontinued for a few weeks before testing. It's a difficult and anxiety-producing situation at best. Hopefully your follow up test will be negative, and that will be a far more reliable exam.

Good luck to you. Please update us as things unfold.

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