[Question #3778] 4th Gen Hiv test 31 days

35 months ago
Thank you for the service provided on this forum. I went on a guys golfing trip in the Dominican Republic in March. While there I had protected oral and vaginal sex with some CSW's from a escort service. 2 weeks after returning I was tested for chlamydia/gonorrhea both which came back negative. The doctor had stated to me that he was not too concerned about the encounters since I was safe even with the oral, which I see from reading this forum seems to be acting overly cautious. I returned 31 days past exposure and had blood testes done for syphilis as well as a 4th gen HIV test which also came back negative. I have seen on several websites and forums that 28 days is a reliable test result when using a 4th gen HIV test. I have also seen 6 weeks is needed. My question is can I move on from this exposure and be confident in the 31 day test results or do I need to retest. Also what kind of accuracy would the 4th gen test show at 31 days past exposure. Again thanks for your insight.      
Edward W. Hook M.D.
Edward W. Hook M.D.
35 months ago
 Welcome to our forum and thanks for your confidence in the advice we provide.  I'll be glad to comment.  Before I address your specific questions however let me point out that condom protected sex, when condoms are worn throughout the encounter, is safe sex with virtually no risk of STI's including HIV. Your test results so far prove this.  I agree with your doctor,  I would not be worried about this encounter. 

 Confidence in test results depends not only on the test that is performed but the circumstances of the encounter which lead to the testing. In your case the encounter was a virtually no risk in counter. This makes evaluating test performance easy.    Interpretation of combination antigen antibody tests has changed in the past year. Previously we said with great confidence that results of these tests were definitive at four weeks following exposure.    More recently however investigators at the CDC have found a very small number of persons who is tests have become positive beyond the four week time period.    As a result both the CDC and we have changed our recommendation to now tell clients that these tests are only absolutely definitive at 6 weeks after weeks after an encounter of concern.   Despite this change, you can be confident that over 99% of persons will have definitive test results within four weeks of their exposure.   Neither of us on this forum has ever seen a person who's tests were not conclusive at the four-week time Period.  In your case given the very low risk of the encounter and your test results at four weeks I would consider your results definitive and, were I you, I would not worry and would not feel the need for additional testing.

 I hope these comments are helpful to you. BWH. 
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35 months ago
Than you for the reassurance as I resumed unprotected sex with my GF after I received all of my negative results.
Edward W. Hook M.D.
Edward W. Hook M.D.
35 months ago
Glad to be able to help. Take care.  EWH
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34 months ago
Hello Dr. 

Sorry for the delayed reply. Out of an abundance of caution and given the way my mind works. I went for a confirmation test at 12 weeks yesterday and am currently waiting for the results to come back. My question is two fold . One, am I correct in believing that these results coming back positive given my negative results with a 4th Gen test at 31 days would be virtually zero and also this time the Dr ordered just an anti-body test. Does that change any confidence in my results or would it be normal to switch from a 4th gen test to a anti-body only test 12 weeks out?

Thanks for the help
Edward W. Hook M.D.
Edward W. Hook M.D.
34 months ago
The 4th generation, combination HIV antigen/antibody test is typically more sensitive and a preferred test over the antibody only tests.  OTOH, the further out you are tested, the less difference there is in the performance of antibody only vs antibody/antigen (4th generation) tests.  If your 12 week test is negative, I would urge you to believe it and have complete confidence that you did not get HIV from the low risk exposure you have described.  EWH
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