[Question #3634] Post PEP Testing

33 months ago
* Unprotected MSM anal intercourse with ejaculation; source = top; exposed = bottom

* Source tested negative all STIs, eleven days post exposure (HIV duo)

* Source 64 yrs. old, white, educated, employed professional; monogamous (heterosexual) relationship 40 years

* Source denies engaging in receptive intercourse ("only 'tops'"); source creditable

* Source resides in low-prevalence locale

* Exposed completed thirty-day course of PEP, and was timely (< 5 hrs. delay) and consistent (no late/missed dosages)

* Six weeks post completing PEP, exposed presents no indication of seroconversion

* At baseline, exposed tested negative all STIs (HIV duo)

* Five weeks (thirty-seven days) post exposure, exposed tested negative all STIs (HIV duo)

How conclusive the five-weeks post exposure testing?
H. Hunter Handsfield, MD
H. Hunter Handsfield, MD
33 months ago
Welcome to the forum. Thanks for your confidence in our services.

You can be 100% certain you did not acquire HIV. (I'm assuming the "exposed" partner is you.) Your questions themselves indicate you pertty much understand why. However, because you had PEP, you're going to need another HIV test 3 months and, according to some experts, 6 months after exposure.

This was a high risk exposure in that your partner has unprotected anal sex with other men. Being only an insertive partner (top) and residing in a low-prevalence area do reduce his risk, but it's still a high risk situation based on partner selecttion and the nature of the exposure. On the other hand, with him having a negative duo test 11 days after exposure, you can be nearly certain he wasn't infected at the time of the exposure.

So I would not have recommended PEP; or would have advised you to stop taking it when you learned your partner's negative test result.

All things considered, I would estimate the chance you have HIV to be under 1 in a hundred thousand. But becuase of the theoretical possibility your partner was ain the window period when tested, that cannot be guaranteed. As implied above, most experts advise that test results after taking PEP requires delay of testing to 3 months after exposure, and some experts advise 6 months. There are absolutely no data on this, so we're dealing with expert opinion only. But I would advise you have at least 1 more test at 3 months and perhaps one more 6 months after the exposure. Alternatively, your partner could be tested again. A negative duo test at 6+ weeks after your encounter with him would also prove conclusively you were not exposoed.

As all this implies, you are experiencing one of the common downsides of PEP:  While it certainly is recommended for potentially high risk exposures to HIV, it usually prolongs the period of uncertainty by extending the test window by several weeks (except when the partner is available and willing to be tested).

In the meantime, stay relaxed. The chance you have HIV is nearly zero and almost certainly any additional tests you do will remain negative.

I hope this information is helpful. Let me know if anything isn't clear.

HHH, MD
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33 months ago
Thank you for the prompt and thorough reply. And thank you for your suggestion: am going to ask the source to be retested.

A timely/consistent/complete course of PEP: in your experience, how effective?



H. Hunter Handsfield, MD
H. Hunter Handsfield, MD
33 months ago
Thanks for the thanks. I'm glad to have helped.

The effectiveness of PEP has never been studied in clinical situation, i.e. HIV exposed humans. It would be ethically impossible to treat some but not ohter exposed persons, which is the only kind of research that would nail it down with certainty. But studies in animal models (e.g. primates) have been promising, and to my knowledge there have been no reported cases of new HIV following PEP, in the absence of major lapses in dosing. So the data suggest PEP is almost 100% effective, but we can't say more than that.
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33 months ago
Please clarify: "A negative duo test at 6+ weeks after your encounter with him would also prove conclusively you were not exposed."

6+ weeks post exposure--or 6+ post completion of PEP?

Thank you very much, Dr. Handsfield.

H. Hunter Handsfield, MD
H. Hunter Handsfield, MD
33 months ago
My comment about testing at 6+ weeks after your exposure was referring to your contact, not you. If he had a negative test 6+ weeks after your sexual contact with him, then for sure you were not exposed and do not need any further testing. If that isn't done, then you should be tested at least 3 and perhaps 6 months after the exposure. (After exposure, not after completion of PEP.)
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