[Question #5991] 4th Generation Window Period

Moses Isaiah
19 months ago
Hello Doctors,

I was exposed to an HIV+ partner with a high viral load last 15 July. I assume he has a high viral load because he was reluctant to answer my question of whether or not he had risky encounters prior to his nonreactive January 2019 test. My exposure was brief (more or less 3 seconds) unprotected insertive anal sex. I took two (2) 3rd Gen Antibody tests on my 4th and 6th week, and a 4th Gen Ab/Ag test on my 8th week (54 days post-exposure). All three were negative.

On the 3rd week of the exposure, I had a fever, rash on my palms and foot soles, and some muscle aches. I was diagnosed by my GP with Hand, Foot, and Mouth Disease. What really terrified me was that after about two weeks, I caught a cold (with coughing lasting to about 2 weeks). I felt like something’s wrong because these were two illnesses in less than two weeks. 

I understand that the window period for the 4th gen test is up to 6 weeks (42 days), but my doctor also said that there may still be a *slim* chance of seroconverting up to the 12-week period. That being said, he did mention that their tests were "more advanced" than the commercial 4th gen tests and their test’s window period was around 4-6 weeks. The tests were sent to a lab and I got the results 8 hours after extraction.

My question is, can I put this exposure behind me? I still have a nagging feeling of malaise, but maybe partly because of my anxiety. That being said, I am also terrified of rationalizing things when I may have HIV so I can’t relax.

Thank you doctor.
Edward W. Hook M.D.
Edward W. Hook M.D.
19 months ago
Welcome to our Forum.  Irrespective of what your partner's viral load was at the time you has sex with him, the fact that you have now had multiple negative 4th generation tests including at 6 and 8 weeks following exposure provide you with reliable evidence that you were not infected by that exposure.  To our knowledge and as per the latest information from the CDC, other than persons who are taking anti-HIV PEP or PrEP for HIV prevention, there are no instances in which persons have had negative tests at 6 weeks and then gone on to have a positive test.  On occasion persons will state that there is a "slim chance" rather than say there may be new data but the fact is, we follow this information and are unaware of any data to suggest that 6 week tests are not conclusive.  I have no idea what he might have meant by "more advanced" test so I cannot comment on this other than to say that the tests you have described are reliable and conclusive and should be believed.  Than another test of some sort confirms those results should, if anything, strengthen your confidence that you do not have HIV.

I hope that this information is helpful to you and will help you to move forward.  EWH
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Moses Isaiah
19 months ago
Dear Dr.  Hook:

I appreciate the time you took to reply to my query. Just to clarify, however, my 6-week test was an SD Biolone HIV 1/2 3.0, and my 8-week test was a laboratory 4th generation one. 

That being said, I have a friend who apparently seroconverted during his 4th week which lasted up to the 6th week post exposure (said he thought it was dengue (flu, rashes, etc.)) which the rapid antibody tests didn’t pick up until his 3-month mark. 

Should I continue to be worried despite my 8-week (54 days) 4th generation HIV nonreactive test result? I still plan to take a 12-week 4th gen test for peace of mind, but I just wanted to ask if there is still any chance of me seroconverting late like what happened with my friend.  I’m having unusual back pains which I hope are just psychosomatic manifestations of weeks of stress and anxiety. 
Edward W. Hook M.D.
Edward W. Hook M.D.
19 months ago
Thanks for the additional information.  It in no way changes my assessment or advice.  The rapid tests that you refer to detect only antibodies, not antigens and antibodies what are detected by 4th generation tests.  Your 3rd generation tests at 4 and 6 weeks would have detected over 90% of recent infection but not all.  OTOH, your 8 week test is entirely reliable and should be believed.  Further, when symptoms are present, 4th generation HIV tests are virtually always positive as the symptoms of early HIV (the so-called ARS) are due to interactions of high concentrations of virus and antibodies.


I cannot comment on your back pains which may be deserving of their own, separate evaluation  but certainly anxiety and stress can contribute to and accentuate such problems.  EWH    
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Moses Isaiah
19 months ago
Thank you for taking the time to reply doctor:

I've begun the process of eliminating my anxiety by starting to believe in my test results. Thank you for the reassurances of my 8-week 4th gen test to be reliable and conclusive. For my final follow up question, this is going to be more along the lines of understanding the testing process itself. 

I've read several answers, primarily by Dr. HHH, that 4th generation tests will detect either the p24 antigen, the antibodies, or both by 45 days or later. But my question is:

Why don't rapid antibody tests (primarily by the finger prick or oral swab tests) detect 100% of acute infection cases by the 45th day if the p24 antigen levels drop to undetectable levels by then and if in theory the body should be then producing detectable amounts of antibodies to fight off a possible infection? 

There were talks of a "second" window period between the antigen and antibody tests of the 4th generation tests and I would like to understand that even more (manufacturers of finger prick tests advertise that their tests are sensitive enough to detect early infections). Your answers will definitely put my mind to rest (there's still a small doubt in my mind regarding the definitiveness of my 4th gen test) and give me the confidence to move on from this incident.

If possible, could you also post suggested readings so I can have a look at them, and also for the benefit of anyone who might have the same questions.

Thank you very much doctor. More power to you and the rest of the ATE staff.
Moses Isaiah
19 months ago
Just additional information to my last question:

Why did my friend who was seroconverting (experiencing dengue-like symptoms) tested negative during his rapid finger prick antibody test? Is it also the same for me?
Moses Isaiah
19 months ago
Oh and last additional information:

I may also have genital herpes, but they were asymptomatic as of time of testing. Would Herpes affect my test results?
Moses Isaiah
19 months ago
Edit: Please forget my last reply. I found out that HSV does not affect the window period. 
Moses Isaiah
19 months ago
Edit 2: Please scratch my last reply. I cannot find straightforward answers as to the effect of HSV to the development of HIV antigens and antibodies, which could potentially affect my 8-week 4th gen Ag/Ab test.

Please forgive me, doctor. I am currently trying to recover from the HIV scare (to which you have provided me the necessary assurances that my 8-week 4th gen test was conclusive), but my mind is a bit restless at the moment. Which is why I still plan to take a 12-week 4th gen test to put this all behind me (I'm not sure if I'm totally off the hook yet).

Please consider these my last two questions (on my 3rd and 5th reply to this thread) as my final follow-up questions regarding HIV window period testing reliability.

Thank you doctor, and have a great day ahead!
Edward W. Hook M.D.
Edward W. Hook M.D.
19 months ago
Five follow-up responses.  Clearly you remain concerned about your exposure which is a natural reaction to a known exposure.  Although you do not say so directly, your follow-up questions also suggest that you have been on the internet seeking answers.  I urge you to stop this or at least visit ONLY reputable sites such as those provided by the U.S. Centers for Disease Control (CDC).  The internet is quite full of incorrect, out of date and misinterpreted statements.   For instance, the idea of second window is totally incorrect.

During sero-conversion to HIV a sequence of events occurs which can impact test results for a few days.  Following infection and before the body begins to produce antibodies, there are high concentrations of circulating HIV virus.  During this period persons are asymptomatic and the 4th generation tests will detect antigen (the virus) but not antibodies (which have not yet been produced).  Then, as antibodies to the virus begin to be produced, all of the antibodies produced bind to the circulating virus; at this time antibodies are still undetectable with antibody only tests such as finger stick tests because the antibodies have been stuck to the virus (4th generation tests are positive at his time however).  During this initial period as antibodies are produced, the combined virus and antibodies also cause the Dengue-like symptoms you describe, severe muscle and joint aches, high fever, etc.  Over just a few days however, the antibodies continue to be produced and partially control the virus, at which time antibodies become detectable, low concentrations of antigen (virus) are detectable, and symptoms resolve.  At his time both 4th generation and antibody only tests such as the finger-stick test are positive and will remain positive going forward (always).

Once again, I assure you that your 8 week test results are conclusive.  

As per forum guidelines, and as this is my 3rd response, this thread will be closed.  I hope that my responses have been helpful.  Believe your tests.  EWH
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Moses Isaiah
19 months ago
Thank you Doctor! You’ve been of great help!