[Question #6403] Possible HIV/STD Exposure question

16 months ago
I met this girl at a bar last weekend. Afterwards, we both gave each other oral sex. Then, she asked whether I have a condom or not, which I do. I put on a condom and try to do a penetrative sex, which didn't work because I drank a little bit too much. Thus, we continued with only oral sex. I did not ejaculate at all. I double-checked the condom to ensure that it didn't break, which it didn't. I did not ask her whether she had any STDs and I don't have any way to contact her right now. We are both asians if that matter at all.

A day and a half later, I felt paranoid. I went to the ER and got prescribed PEP, which I have been taking for the past 2 days. I took it right at the 36 hour mark after exposure. I am anxious right now about the risk for HIV. I have planned a chlamydia and gonorrhea test for Thursday, which will be 3-5 days recommended waiting time for those two. However, I am not sure what to do with HIV.

My question is:

1. Should I continue with PEP given the risk factors? Is there a general rule for taking this drug other than to take it once daily (does it have to be eaten at the same time everyday, like 10 am everyday?)
2. If I decide to continue with PEP, will it interfere with future HIV testing if I decide to take an RNA HIV test around 12 days after exposure/4th generation test after I am done with 28 days PEP?
3. Just in general, do you have any advice for me to handle my this? Should I be worried at all? I regret what I did and I felt like I should have asked her about medical history beforehand.
H. Hunter Handsfield, MD
H. Hunter Handsfield, MD
16 months ago
Welcome to the forum. Thanks for your question.

Outside particularly high risk areas like sub-Saharan Africa, southern Asia, or eastern Europe, the chance any particular sexually active woman has HIV is very low, probably less than one chance in a thousand. And oral sex is low to zero risk:  there has never been a proved case of HIV being transmitted by cunnlingus (oral vaginal exposure) or to the penile partner in fellation (oral-penile). Certainly I would not have recommended PEP in this situation. There really is no signficant risk of HIV. The chance of gonorrhea or chlamydia from this event also were very low, but I'm glad to hear you were tested and negative.

1. Once someone is in direct medical care, this forum will not interfere or modify the recommendations of one's personal health care provider, in this case the ER you visited. While I would not have recommended PEP, I also will not advise you one way or the other on continuing it. But if you continue it, a few hours difference one day to the next makes no difference in effectiveness in effectiveness.

2. PEP taken for the full course (usually 4 weeks) may delay test positivity, if PEP doesn't work. If you stop, it would be reasonable to have an RNA test about 2 weeks after the last PEP dose, but no earlier.

3. If I were you and somehow found myself in this situation, taking PEP would not even have entered my mind. Indeed, I wouldn't even feel the need for an HIV test at all.

One solution to all this, if you are able to identify and contact your partner, is to ask her to be tested for HIV. You could also be tested -- you might find she is as worried about this event as you are. After all, women are at much higher risk for HIV from their male partners than the other way around. If both of you were tested and negative, both would know there was no risk and nothing to worry about.

I hope these comments are helpful. Let me know if anyhing isn't clear.

HHH, MD
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16 months ago
Thank you for your reply.

I have been trying to identify and reaching out but so far it hasn't been a success. One thing I am not clear is that if I do RNA test while on PEP and it turns out negative, is it a larger probability that it's going to be false negative? 
H. Hunter Handsfield, MD
H. Hunter Handsfield, MD
16 months ago
There is no chance of a positive RNA test while taking anti-HIV drugs. Don't waste your money.---
16 months ago
Hello,

Thanks for your response.

I have a couple more folllow up questions:

1. What are the effectiveness rate of PEP assuming I adhere by the dosage for the full 28 days? I have seen it to be as high as 92%, but it does not specify the relative success rate towards the timing of first intake. Do you think taking PEP at 36 hours after exposure would decrease the rate of success by a lot compared to say, 12 hours after exposure?  

2. 
16 months ago
Oops I accidentally press the submit button before I finish my question. Sorry

2. Since according to you my risk of exposure to HIV is little to none, I don't need to be worried right? Do you think I need to test at 4 weeks after exposure? For antibody/antigen tests, how's the success rate for testing at 4 weeks compared to say 3 weeks or 6 weeks?
H. Hunter Handsfield, MD
H. Hunter Handsfield, MD
16 months ago
1. There actually are no precise data on PEP effectiveness, but the 92% figure probably is too low for treatment started at 36 hours. Probably close to 100%, but that's just an educated guess.

2. I agree, no risk. If I had been in your situation, I would not even be HIV tested and certainly would not have started PEP. As for timing of testing, that's also uncertain, but most experts advise a final test at least 6 weeks and some would say as long as 3 months after finishing the drug. One of the downsides of PEP, especially in low risk settings, is prolongation of anxiety because it takes so much longer to have conclusive testing and the reassurance it brings. Probably the AgAb test would be always be positive 6 weeks after the last dose, but since there are no data, all we have to go on is expert opinion. That said, the reason we don't have precise data on this is reassuring:  it's because failure of PEP is so rare that there are no data on how long it would take for positive test results in those rare failures.

That completes the two follow-up exchanges included with each question and so ends this thread. I hope the discussion has been helpful. 
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