[Question #3492] Testing after pep

35 months ago
Hi dr

I hope you can help? 

After an incident a few months ago I was put on pep. 4 weeks and 7.5-8 weeks after pep I had 4th generation tests and both came back negative. My question is- is a negative result at 7.5-8 weeks after the completion of pep conclusive? As there are different info out there saying yes and some saying you need to wait till 12 weeks? Hope you can help? 
Edward W. Hook M.D.
Edward W. Hook M.D.
35 months ago
Welcome to the Forum.  I'll be glad to comment although I'm not sure it will clarify things much.  You are correct, recommendations for PEP follow-up vary and, unfortunately have not been updated for nearly two years.  Most governmental agencies recommend follow-up HIV testing at 4 and 12 weeks after completion of PEP with the 12 week value being most definitive.  These recommendations are conservative however.  The fact is that, if someone is going to fail PEP, newer combination HIV antigen/antibody tests are positive by 4, 6 or 8 weeks.  Thus the further out since completion of PEP you go, the "more definitive" a result is.  In your case, the chances that you acquired HIV from your encounter of concern with a negative 8 week test is extraordinarily low and strong, almost but not completely definitive evidence that you did not get HIV.  You may choose to get a 12 week test but were I you, I would have confidence that I was not infected at this time. 

I hope that this comment is helpful to you.  EWH
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35 months ago
Thankyou for your quick reply, I know you can’t test while your on pep, but reading on here about a conclusive test for someone who never had pep is 6 weeks and I tested at 7.5/8 weeks after pep how come that’s not conclusive? 
Edward W. Hook M.D.
Edward W. Hook M.D.
35 months ago
Not sure I follow your question.  I indicated the official, CDC/NIH recommendations for follow-up.  But, as I also said, were I you, with a negative test at 7+ weeks after completion, I would be confident that I was not infected.  EWH
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35 months ago
Sorry I meant on this the website you and  dr hh say a a negative result At 6 weeks is conclusive. And I tested negative at 7.5/8 weeks after pep, so you say to everyone at  6 weeks who is negative is conclusive wouldn’t mine be conclusive at 8 weeks? 
Edward W. Hook M.D.
Edward W. Hook M.D.
35 months ago
You clearly are not reading what I have said.  I do feel it is conclusive.  That said, we I believe does not line up with official recommendations from CDC and WHO whom we believe are overly conservative. 

This is my third reply to this circular conversation.  As per Forum Guidelines, the thread will be closed in a few hours.  You may reply again but you are not assured of a response.  EWH
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