[Question #3914] HIV test accuracy

31 months ago
Doctors-

I had sex and the condom broke.  I am unaware of his HIV status.  I got tested at 19.5 weeks with an antigen antibody test in a laboratory setting (was from my arm vein.)  I am worried that it may have produced a false negative because my doctor told me I should test until about a year.  I am confused too, because I have heard that autoimmune diseases can delay antibody production.  I have eczema and psoriasis.   I appreciate your answer in advance!  

Am I safe to relax?  Thanks!
Edward W. Hook M.D.
Edward W. Hook M.D.
31 months ago
Welcome to our Forum.  I'll be glad to comment.  From a statistical perspective your risk for HIV is very, very low even before testing and with the HIV test result that you mention is essentially zero.  Most people do not have HIV, even most escorts and even when they do, the statistical risk for infection after a single act of intercourse with an infected person is less than 1 in 1000 to 2000.  This even without testing your risk for infection was just a fraction of 1%. You have now been tested with one of the bests tests available in all of medicine (HIV antigen-antibody tests) at a time when the results are quite reliable.  I would consider you results definitive and would advise my patients in your situation that no further testing is needed.  Your eczema and psoriasis do not change this assessment.  I think your doctor is being a bit more conservative than is necessary.

I hope this information is helpful.  I would believe your results.  EWH
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31 months ago
I know you said to not retest so the 6 month testing guideline is outdated then?  
31 months ago
I guess what I want to know is the chances of delayed seroconversion in my position.  What are the official window periods for this test I had?  Thanks again in advance, I really appreciate it.  
Edward W. Hook M.D.
Edward W. Hook M.D.
31 months ago
Yes, I would suggest that the guidelines for repeat testing at six months and both overly conservative and out dated.  CDC authors have recently also published data which are the basis for the revised recommendation that results with combination tests at 6 weeks are conclusive.

With your current results your risk for "late seroconversion" ( which is now an Internet-sustained myth for persons tested with combination tests) is effectively zero.  We have never seen or heard of any persons with negative combination tests at six weeks to later become HIV positive.

I hope this is helpful.  EWH
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31 months ago
Thank you for your help!  I feel much better!
Edward W. Hook M.D.
Edward W. Hook M.D.
31 months ago
I'm glad I could help.  EWH---
31 months ago
One last thing-  What would make my results change if I was to go get tested at the 6 month mark?  I know you said that I don't need further testing, but something I read which basically said that "even with window periods, you still can't be positive you won't become positive later" is making me go crazy.  Statistically, testing at 4.5 months, what chances would you give it for my results to change???  

I also wanted to let you know that I reached out to the man I had sex with and asked him if he had ever been tested.  He said he had to for work (works in a hospital in finance there.)  He told me he did not have HIV.  

Even with all of this information I still have a small doubt in my head.  Let me know what you think.  Thanks in advance.  I really appreciate all of the work you do...it is incredible.  
Edward W. Hook M.D.
Edward W. Hook M.D.
31 months ago
 Give him the information you have provided there is nothing that would make me worry that you might develop a positive test from this exposure in the future. Statements like the one that you make are sometimes made by persons " just in case "  and overly cautious statements designed to protect the person making the statement. Certainly we learn new information all the time but there is no reason to presume did your test results are not conclusive unless you took anti-HIV  medications or had been receiving cancer chemotherapy I really would not be concerned at all and would consider your results entirely conclusive.   Please don't let these overly cautious statements worry you. 

 This is my third reply to your questions. As per forum guidelines this thread will be closed later today without further replies. I wish you the best. Take care. EWH.  
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