[Question #11311] HIV scare

15 months ago

Hi doctors, I (M) had vaginal sex with a female of unknown HIV status. Was protected to begin with until the condom broke. Stopped immediately after this. I began PEP (kocitaf) 16 hours post potential exposure. Full course was completed properly as instructed. I had a 4th gen test during this period (2 weeks post exposure) which was negative. I then had another 4th gen test along with a full std screen completed at 5.5 weeks post potential exposure which was all negative. I am wondering how conclusive I can consider these tests? Whether more tests are necessary? The chance of seroconversion after the test at 5.5 weeks? Does the PEP regimen affect the reliability of these tests? If I do a third gen test at 4 months post potential exposure is it possible that a test line can be extremely faint (borderline not visible) or should there be enough detectable antibodies by that time that it’s obvious if positive?

H. Hunter Handsfield, MD

15 months ago

Welcome to the forum. Thanks for your question.

PEP probably is nearly 100% effective when started under 24 hours after exposure. I wasn't aware of Kocitaf® but I find it contains the most recommended and highly effective combination of anti-HIV drugs. The time to conclusive testing after PEP is uncertain; it's a difficult topic to study and conclusive research has not been done. However, most experts believe 6 weeks is about right. However 5.5 weeks likely is conclusive as well. You definitely can expect a final test at 4 months (or any other time) to remain negative.

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

HHH, MD

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15 months ago

Thank you Dr. Hunter for the reply. Glad to hear that about PEP being almost 100% effective when started early. I just wanted to clarify when I was saying the test was at 5.5 weeks, I meant 5.5 weeks after the potential exposure not after the PEP was completed. Would have been about 1.5 weeks after the PEP was completed. Can I still consider this test reliable? From what I have read my situation seems relatively low risk?

H. Hunter Handsfield, MD

15 months ago

Some experts believe the window period to a positive test result is not prolonged after PEP, but there is no proof and most experts would agree you cannot rely on a negative result only 1+ weeks after completing treatment. It's reassuring but nowhere near conclusive. One of the downsides of PEP -- which many exposed persons and also their doctors don't understand or don't think about -- is that it prolongs the period of uncertainty until conclusive testing can be done. It's the main reason I would have advised against PEP for an exposure like yours, unless there were strong evidence your partner had HIV. Your situation was very low risk for HIV -- probably no higher than one chance in a million.

But what's done is done. Your negative test result is reassuring but not conclusive. You can have a conclusive antigen-antibody blood test (AgAb, i.e. 4th generation) 6 weeks after your last dose of PEP.

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