[Question #913] 4 weeks after pep result

50 months ago
Hi dr

I know I've ask the question before but still stressing abit,  my last question I stated that I had an incident when a drug user stabbed me with a needle. I went on pep for 4 weeks and after completing the pep i had a 4 generation test at 18 days and 30 days both came back negative! I'm just worried that 30 days isn't enough time for a true 100% accurate result! As many health professionals in the uk say it needs to be 6-8 weeks after you complete pep. My question is, is 4 weeks a true result and also because I had pep and if I did get HIV would it not show up at the 4 week mark as I know pep stops the virus showing up? I just worried as I've just had a child and this would be the end of the world and my herpes have came back twice as much as before and I haven't had them in months! Previously I used to get them every month for the last 2-3 years! This episode being the most I've had! 
Edward W. Hook M.D.
Edward W. Hook M.D.
50 months ago

Welcome to the Forum. I will be pleased to comment.  I do not know the details of your exposure so my reply will be somewhat general.    Before I do, let me make two comments which may be important.  The first is that when taken as recommended, PEP works so well that it is hard to study-few people develop HIV when started on therapy soon after exposure if they take all of there medications.  Definitive answers need to be based on studies large enough to give accurate outcome measures.  When something works as well as PEP, measuring failures is difficult.  Second, please remember that official guidelines tend to be conservative and cautious, preferring to possibly be overly conservative than to provide misinformation.  Both of these factors influence recommendations for PEP follow-up.

When PEP was new on the scene and recommended, repeat blood tests were suggested at 1, 3 and 6 months after completion of PEP.  Since then the tests for HIV have gotten better and we have gotten more experience with PEP.  As a result, the six month follow-up is no longer recommended but the 1 and 3 month follow up testing, using 4th generation tests still are.  There is little doubt that nearly everyone with a negative test at 4 weeks has successfully avoided infection however there remains a lingering, very small doubt that there may be a few failures.  For that reason official bodies such as the CDC and WHO continue to recommend a 3 month follow-up test as well.  I have not seen or heard of patients who took PEP correctly and failed beyond the three month period and would be most surprised if it failed you at this time but the data are not yet strong enough to be 100% sure at this time.  Sorry I cannot be more definitive but hope that this information will be comforting.  They are meant to be.  EWH

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50 months ago
Thanks for reply back I know when I ask the question before dr hhh replied back thst it would be conclusive at the 4 weeks, so I'm a little confused thst you said it's not conclusive at the 4 weeks, sorry just abit worried 
Edward W. Hook M.D.
Edward W. Hook M.D.
50 months ago

Thanks for telling me that you had interacted with Dr. Handsfield earlier.  It allowed me to go back and read his earlier interchange with you and learned that apparently you do not know that the person who stuck you had HIV and that PEP was started within hours of the exposure.  Having read Dr. Handsfield's replies, I am confident that he and I are in agreement.   As I said above, the sorts of details you describe make the likelihood that you were infected incredibly low and your 4 week results make the possibility lower still.  When Dr Handsfield said "It takes 4 weeks for a truly conclusive result. But I have never heard of a patient in this situation who turned out to have HIV. You can expect any further tests to remain negative.", he said essentially the same thing I said when I wrote " I have not seen or heard of patients who took PEP correctly and failed beyond the three month period and would be most surprised if it failed you at this time but the data are not yet strong enough to be 100% sure at this time." although I did mistakenly write "beyond the three month  time period" when I meant to write that I, like Dr. Handsfield have never seen or heard of someone who was found to fail PEP after a negative test at one month.  I apologize for the typo. 

4th generation HIV test results obtained 4 weeks following exposure without PEP are conclusive.  The introduction of PEP into the situation complicates things a little and as I tried to explain, this makes experts a bit more cautious than is the case for exposures in which PEP is not used since there are studies describing outcomes in literally millions of people without PEP.  I do not expect you to be the first person who took PEP correctly within hours of a possible exposure to develop HIV despite a negative 1 month 4th generation HIV test.  EWH     




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50 months ago
So in your opinion is 4 weeks not long enough for a conclusive test and should I wait and go again? If was HIV it's about 6-7 weeks now after stopping pep would I have has symptoms? I've had a few occasions where I've woke up in the night sweating and also my herpes coming back? Just really worrying now thst testi g at the 4 week point won't show a true result 
Edward W. Hook M.D.
Edward W. Hook M.D.
50 months ago

You are over reacting and either not reading or not processing what both Dr. Handsfield and I have been telling you.  Your chances of having contracted HIV are infinitesimal.  The RECOMMENDATION from the CDC and World Health Organization is that you should have a repeat test at three months.  This recommendation is likely to be overly conservative but that doesn't change the FACT that today that is the recommendation.  If I had a million dollars to bet, I would not hesitate to bet that any further follow-up tests related to the possible exposure you describe will be negative.

Fewer than half of persons who acquire HIV have symptoms- that is the reason the blood tests are important.  When people develop symptoms, they do not come and go.

I urge you to believe that the 4 week result and consider the follow-up as more of a formality than a concern,.  EWH

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50 months ago
Ok thanks doctor just struggling as I read so many different things and are all saying different things. And with my my herpes coming back the most of ever had I panic! Just there's so much different info it's really hard who or what to believe! 
Edward W. Hook M.D.
Edward W. Hook M.D.
50 months ago

As you know, we are limited to three responses per question so this thread will be closed later today.  At the same time Dr. Handsfield and I have communicated about your recent (and past) questions and are in agreement on our message to you.  Once more, these are:

That the chance that you have HIV from the encounter you describe is very, very low (a small fraction of 1%) based on the nature of your exposure, that you took your PEP, and your test results so far.  We urge you to go forward and have confidence that you are not infected while still following the official recommendations.

We would also urge you to stay off the internet as much of what you see there will be misleading and incorrect.

This will now end my replies to this thread.  Take care and try not to worry.  EWH

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