[Question #2164] Is tested HIV negative after 40 days conclusive?

48 months ago
I gave an oral sex to a guy on 18 March 2017. Got tested 40 days later on 27 April 2017, rapid HIV test came back non reactive. Did a conventional lab test (HIV 1/2 Ag-Ab, CLIA Liaison XL)result came back inconclusive. So they did further test on HIV antigen (presumably the RNA test) and western blot for HIV antibody. Both came back negative. My Dr. told me to return for another test on 1 June. 
So my questions are: 
Is it conclusive I'm HIV negative?
Why do I need to do another test ? 
Why did the first conventional test came back inconclusive? By the way, I had a cold when I went for the test.
Do I need to be concern with this result? 
Thank you! 
H. Hunter Handsfield, MD
H. Hunter Handsfield, MD
48 months ago
Welcome fo the forum. Thanks for your quesiton.

One of the most consistent themes on this forum is that oral sex is safe sex with respect to HIV and other STDs. It isn't zero risk, but the chance of infection is far lower than for vaginal or anal sex for all STDs, and zero risk for some. There have been very, very few cases of HIV that appeared to have been acquired by performing oral sex, i.e. penile to oral transmission. (There are truly zero known transmissions for penis to mouth or for cunnilingus, i.e. vaginal-oral contact.) One estimate (from CDC) is that performing oral on an infected male has a 1 in 10,000 chance of infection. That's equivalent to giving BJs to infected men once daily for 27 years before transmission might be likely.

For those reasons, HIV testing normally is not done or recommended after exposures like yours. In any case, for sure you are not infected. Inconclusive results on the Ag/Ab (4th generation) HIV blood tests are very rare, but, as in your case, they almost always prove to be negative, as has been found in your case. The combination of repeat antigen testing (perhaps a test for p24 antigen; if it was RNA they probably would have called it an RNA or PCR test) plus Western blod is conclusive at ~5 weeks after exposure. To your specific questions:

1) Yes, your results are conclusive.

2) Your doctor apparently is just more conservative about such things, and doing another test a few weeks later is common in situations like this. It's just a question of being careful. YOu can definitely expect another negative result. (Remember that the chance you were infected was only 1 10,000 even if your partner had HIV, which he probably didn't.)

3) As I said, this is a rare outcome. The explanations for false positive or inconclusive tests aren't known. They do not appear to imply any problem with health or the immune system. I doubt your cold had anything to do with it, but cannot say for sure. Certainly I have not avoided HIV testing in people with colds and will not do so in the future.

4) Nope, no concern. Stay mellow pending the final test.

I hope this information has been helpful. Best wishes and stay safe--  HHH, MD

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47 months ago
Dear Dr Handsfield
Many thanks for the prompt reply and the reassurance of my test results to be conclusive. 
Out of curiosity, how accurate are both the HIV P24 antigen test and Western Blot? I understand that western blot is being used as confirmatory test. And what are the window period for both tests. 
 Thank you!
H. Hunter Handsfield, MD
H. Hunter Handsfield, MD
47 months ago
That combination is 100% conclusive. The window period for p24 antigen typically is 10-14 days, but it becomes negative again after a few weeks or months. The WB antibody test has a window period of 3 months. Everybody with a new HIV infection is positive for p24 antigen or antibody after ~4 weeks.

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47 months ago
Dear Dr Handsfield
I got my HIV test results back. Exactly identical to the first test I did a month ago (reactive to the combo test; non-reactive to both Antigen P24 and WB Antibody tests). My Dr. said it is conclusive I am all clear. 
She advised that I mention this situation in my future tests. 
She said apparently other type of antibodies might have set off the system. 
What is your view on this? 
Thanks!
H. Hunter Handsfield, MD
H. Hunter Handsfield, MD
47 months ago
I am unaware of recent new research on false positive or inconclusive HIV tests; most such work is over 10 years old. If there has been recent work on the combo test in particular, I am unaware of it. Based on the available studies, the cause(s) of such results were and remain unknown. However, they carry no known health implications. In any case, I agree with your doctor:  you do not have HIV; and if you have HIV testing in the future, perhaps best to avoid the combo tests entirely -- or at least learn exactly which test has given the inconclusive results (i.e. the particular brand name) and avoid that one.

That concludes the two follow-up comments and replies included with each question, and so concludes this thread. Take care and stay safe!

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