Recently I was in NYC and hired an escort. For what it is worth, she charged about $1000 and did not seem to be a drug user as far as I could tell. Both of us are white (however she is from Venezuela). I am circumcised.

We were having protected vaginal intercourse and when she got off of me, the condom was no longer on my penis. She quickly pulled it from around or in her vagina and threw it out. We also had unprotected oral sex.

My concern is I am not sure when the condom came out so I am incredibly worried about HIV risk.

1.  Assuming the condom was totally off for at least some period during sex, how risky was this and do I need an HIV test?

2. If I get an HIV test I can do an RNA test much earlier. However my fear is the false positive rate could be higher than my actual risk so maybe that is a bad idea. Thoughts?

3. How accurate would a 21 day duo test be in your opinion? I was thinking this could at least alleviate my anxiety until 28 days if the result is meaningfully predictive.

Thank you for your advice.

 You do not say specifically however it appears that your encounter occurred about three weeks ago. Is that correct? If so, the apparent absence of symptoms at this time is also a good sign.  With that general comment let's address your specific questions: 

1.   Few commercial sex workers are infected with HIV, and even if she were the risk for acquisition of infection following a single sexual encounter is about one infection per 2000 encounters.  Thus your chance of infection is tiny, less than 1 in 100,000.

2.  RNA tests do become positive earlier than other tests for HIV. Having said that at four weeks you can be tested with a combination HIV antigen/antibody test and be completely confident that you were not infected. As you also suggest, the risk of a false positive test is slightly higher with the RNA test then with the combination test.  I am confident that when tested, you will find that you did not acquire HIV from the encounter you described.

3. At 21 days a negative duo would be strong, but not perfect evidence that you did not get HIV.

Finally,  and perhaps more importantly, you do not mention testing for other, more common STIs such as gonorrhea or chlamydia whichare more common than HIV, are sometimes asymptomatic, and can easily be diagnosed with a simple urine test. I would encourage you to get one just to be sure ( I doubt that you have these infections either but I realize that you want to be as short as possible. )

I hope these comments are helpful to you. Please feel fee free to follow up if there are further questions.  EWH

I am awaiting the results of the ghonorea and chlamydia tests but they should be back soon.

The incident was only about 11 days ago.  Based on this, do you think it would it be worthwhile taking an RNA test now or waiting for 28 days for a single Duo test? 

(Or, like I was considering also taking a Duo test at 21 days and another at 28 days.)

I would very much like to take an RNA test and they are less costly than I anticipated at Quest, but I am very concerned about false positives as you can probably tell. 

Are there any reliable figures on false positives?  I am afraid that if a false positive is more likely than my own risk, I might be acting foolishly to take the test.

Also, is there any range of reliability at 11 days if I did take the RNA test and it were negative?

Finally, and this is nitpicky and driven by anxiety, but when you note less than 1/100,000, should I take that as a suggestion this person was at higher risk than most CSWs? 

(I had read elsewhere in your group's advice that, the rate was 1/100 to 1/1000, which would be lower than 1/50, which the below would seem to suggest if the risk were 1/100,000.) 

On the other hand, I understand you said "less than" so maybe I am overthinking that you are simply providing ballpark figures. If so, simply chalk it up to anxiety and forgive the question.

Thanks for the additional information.  I'm glad you have tested for gonorrhea and chlamydia.  My own advice is to realize that your risk for having acquired HIV is tiny and to hold off getting the RNA test.  While I cannot give you a precise figure as to the false positive rate, I can tell you that we regularly see patients whose RNA PCR tests are falsely positive.  On the other hand, I have never personally had a patient with a false positive duo test.   A negative duo test at 21 days would be further evidence supporting that you did not get HIV from your encounter but as I said, I would not consider it definitive until 28 days when, for all practical purposes you could consider the result definitive. 

From what you have described, if anything, your CSW partner was on the low end of the risk spectrum, not the high end.  Higher cost CSWs are less likely to be infected and you already know that she uses, condoms, the problem was just that it came off. 

Please try not to worry.  I am confident that your tests will be negative.  EWH

That was super helpful. I am going to forgo the RNA test in that case.

One final question and I will never darken your door again.

I am thinking of doing a 16 day Duo test on Monday. Does that have any meaningful predictive value if negative?

If so, is there even a ballpark range you could put on it?

This would not be in lieu of a 28 Duo test.

Thank you again for all of your advice!

Great, I do think forgoing the RNA test is a good idea.  What I neglected to say in my original reply (sorry) was that my back of the envelope calculation is that your risk for a false positive results was about as high or perhaps higher than your risk for HIV.

With regard to testing before day 28 with a combined HIV antigen/antibody test, the HIV antigen typically appears between day 11 and 14 after exposure and on average antibodies begin to appear around day 21.  Thus a negative day 16 test would be further support that you did not become infected but not definitive.  Precise estimates of what proportion of infections would be detected is difficult to say but I would guess that by day 16 at least half of recent infections would be detected with that proportion increasing statistically on a day-by-day basis. 

I hope this is helpful. Please do your best not to worry- your risk for infection is very, very low.  As you also know, this is my third reply to your questions.  Hence there will not be further replies and this thread will be closed later today.  Take care.  EWH.