[Question #8343] HIV Risk + PEP

45 months ago

Hello,

I had a possible HIV exposure risk about a month and a half ago. Although the individual said they recently tested negative three weeks before (routinely every three months) and were on PREP, I didn't know them that well. I am circumsized and was the insertive partner, unprotected sex, lube used, no cuts or blood to my knowledge. Out of precaution, I got on PEP 36 hours later, 28 day cycle. They said I was low risk. I got a fourth gen combo test two days after finishing my cycle of PEP, so 30 days after exposure. Came back negative. How accurate would you say this result is? Would the PEP impact the window period? Having a lot of anxiety, depression, and feel like I've potentially ruined my life. You said you've never had a patient that tested negative at 4 weeks that later test positive right? I saw a post of yours I think on MedHelp that said if they say they are negative just forget the whole thing. What are your thoughts?

Thanks,

H. Hunter Handsfield, MD

45 months ago

Welcome to the forum. Thanks for your confidence in our services.

I agree this was a very low risk exposure; I would have recommended against PEP. A problem with PEP, often not considered by patients and the doctors who prescribe it, is that if PEP doesn't work, it may substantially delay the time to positive testing. Therefore, it prolongs the uncertainty by several weeks. The testing clock starts when treatment is complete; your antigen-antibody (AgAb, "4th generation") only 2 days after stopping may be slightly reassuring, but that's all: you really can't have a reasonably reliable result before around 3 weeks after the last dose of drug, and the result isn't conclusive until 6 weeks after the last dose. It is true that I have never had (or heard of) a patient who tested negative with an AgAb test 4 weeks after exposure -- but exposure isn't the date that matters here.

But going back to the risk level, it is true that PrEP is highly effective in preventing infection, and also in preventing sexual transmission to partners if infected. So you can stay mellow and relaxed as the time passes and you wait for conclusive testing. There is no realistic chance you caught HIV.

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

HHH, MD

---

45 months ago

Wouldn't the antigen surely show up if the antibodies were delayed? I spoke to an HIV/AIDS specialist and they said PEP does not delay the window period but the mutation of the virus. Accuracy 99.9% effective they say. Is this correct? Of your patients who took PEP have any tested positive after 4 weeks? I took every dose and no repeat exposures since then and don't plan to again. The length of the encounter kind of concerns me. We went at it for awhile. They were in the their early 50's. I see them online sometimes still (Grindr). I just hope the person did not lie to me. I asked them a lot of specifics before and after the encounter and they really seemed legit, but was a terrible mistake trusting a stranger. I am trying to remain calm but am losing it. So scared.

Thanks,

H. Hunter Handsfield, MD

45 months ago

Interesting advice from the specialist you spoke with. But I have to respectfully disagree: PEP definitely extends the window period. To make sure I haven't missed some recent research developments or recommendations, I reviewed the CDC guidelines about PEP follow-up, and also made inquiries of some colleagues closely involved in PEP research and recommendations. They confirmed the advice I gave above and I'm sticking with it: testing as soon as 2 days after completing PEP says nothing at all about whether the PEP was effective in preventing HIV. Officially, CDC advice is for testing at 6 weeks and 3 months after completing PEP; but my expert colleagues agree that a negative result with AgAb testing 6 weeks after completion is sufficient and conclusive. And no, I have never had a patient (or even heard of one) who tested negative at 4 weeks (after exposure or after completing PEP) who had a positive result at 6 weeks. But rare things happen: I've also never cared for a patient struck by lightning, but that experience has no bearing on your risk of being struck.

If antigen "shows up" in the blood, antibody is never delayed more than a few days. That simply never happens in HIV infection.

In any case, none of this warrants "losing it" or being "so scared". You had a nearly zero risk exposure. That plus PEP reduces the chance you caught HIV to well under one chance in many million. The level of fear you express is irrational. Try to think objectively and calmly. And don't confuse your anxieties about a sexual experience you apparently regret with infectious consequences of that decision. They aren't the same.

---

45 months ago

Gosh, the well under one chance in many million has made me feel a lot better. I will try to calm down and think objectively like you say. I have a tendency to be a worry wart. Thanks doc.

H. Hunter Handsfield, MD

45 months ago

Thanks for the thanks -- I'm glad to have had some success in reassuring you. That's why we're here!

That completes the two follow-up exchanges included with each question and so concludes this thread. Best wishes and stay safe!

---