[Question #6624] HIV 4th Generation Test after PEP

14 months ago
Hello, 

I am back here with some questions. I posted here around 8 weeks ago about my very very low risk sexual exposure.

I finished my course of 28-day PEP.  Moreover, I recently got tested with 4th generation HIV lab test 4 weeks (28 days) after my last dose of PEP (8 weeks after exposure). It came out negative, which is expected. I just have a few questions:

1. Is the result conclusive enough? Do I need further testing in the future? I want to make sure so I don't have to waste money on further testing. 

Thanks again !
14 months ago
The reason I am asking is that I have read some information that I should get retested in 3 months. However, seeing some of the posts here lead me to conclude that 4-6 weeks test after PEP is conclusive enough. 
Edward W. Hook M.D.
Edward W. Hook M.D.
14 months ago

Welcome back to the Forum.  On this occasion I happened to pick up your question rather than Dr. Handsfield but I reviewed his earlier interactions with you and agree with all that he said, including that I would not have recommended PEP for you.  I hope that these replies will help you to move forward.  For persons with known exposures to HIV infected persons (unlike your close to not risk event) PEP reduces the likelihood of acquiring HIV by about 80%.  Because few people get HIV following PEP there are few data on precisely when testing is conclusive.  For that reason virtually all expert sources say that testing at 3 months is recommended for conclusive results.  These recommendations may be overly conservative but in the absence of data that is where things stand. 

Bottom line, 4 weeks after completion of PEP, while likely to be accurate, is too early to be recommended as conclusive. 

In your own case, between the virtually no risk nature of your exposure AND the fact that you took PEP, AND the fact that you have a negative test 4 week test I am confident that you have not acquired HIV from the exposure you describe.  If I were you I would not feel the need for further testing  but if you are going to follow the recommendations for testing following PEP, you need another test in 4 weeks.

I hope that this information and perspective is helpful.  EWH

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14 months ago
Thank you for your response, Dr. Hook !

I have read one of the post here, which is question #6325, where Dr. Handsfield wrote that 4th generation test 6 weeks after PEP completion is conclusive. 

I also forgot to say that 2 weeks after the exposure, I managed to reach out to the person and asked about her STD status. Luckily, she told me that she does not have any current/history with STDs. I know that I should not trust strangers right away, but after reading some of the posts here and based on your experience, people usually tell the truth when asked about their STD status.  I continued with PEP after she told me about her status anyway since I am already halfway through the 28 days dosage. 

I just have a few questions to close:

1. Do you think it is safe for me to engage in sexual intercourse with my regular partner?
2. From your experience, what are the main difference between symptoms of ARS (acute HIV infection) and flu, for example? I don't have any symptoms, I am just curious since I have read that they present similar symptoms.
3.  How would you compare the reliability of a 4th generation rapid test which detects both antibodies and antigen using blood from finger prick compared to the lab test? 

Again, I want to thank you and Dr. Handsfield for having this forum. It is a very great resource to learn about HIV, especially with a lot of misinformation throughout the internet these days.
14 months ago
Of course, I also want to thank Terri Warren too even though I have not been involved with her. All of you provide awesome resources for questions about STDs/STIs
Edward W. Hook M.D.
Edward W. Hook M.D.
14 months ago

While I agree with Dr. Handsfield if he said that related to situations following completion of PEP, and we are in agreement for persons who have not taken PEP that a 6 week test is conclusive, as I said above, the official recommendation, which may be conservative, is three months. 

1.  Yes

2.  There is much overlap between the symptoms of the flu and the ARS.  That is the reason we rely on the tests. 

3.  The fingerstick and venous blood tests are held to the same performance standards by the FDA.

thanks for your thanks.  I'm please our Forum has been helpful.  EWH

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14 months ago
So based on Dr. Handsfield and your evaluation,  it seems that I am overly worried about an exposure that carries basically no HIV risk. I do have anxiety problems which I have already sought help on.

One more question: I also looked up resources from BASHH guidelines for PEP monitoring and follow-up. They recommend following up with 4th generation test 8-12 weeks after exposure. My question is, why is the margin so large? How would you interpret this? Do you think following this guideline would mean that any test between 8-12 weeks after exposure is good enough?


Edward W. Hook M.D.
Edward W. Hook M.D.
14 months ago

The BASHH guidelines, like those of the CDC which are slightly more conservative coming out for 12 weeks after exposure, are both likely overly conservative and reflect the lack of good data on the timing of failure following unsuccessful PEP.  Most official organizations in such situations err on the side of being overly conservative rather than take a chance of being wrong as more data become available. 

Given the no risk nature of your exposure, my sincere advice is to put your concerns aside and move forward. 

This is my 3rd response.  Therefore as per Forum Guidelines, this thread will be closed shortly without further eplies.  EWH

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14 months ago
Thank you for your thorough explanation and reply, Dr. Hook ! It has been very helpful ! I will do my best to follow your advice to put aside my concerns and move on.