PEP medication and hiv testing

Question

Hi. I am a male. Last week, I had anal sex. I asked the status of the other guy and he told me he was negative. I insisted we use a condom. In the middle, without asking or telling me, he pulled the condom off and inserted back in me. I noticed right away and pushed him out maybe after three seconds. The next day, I went to a clinic and was prescribed PEP -- truvada. I have the following questions:

(1). Are there any studies, in terms of percentages, regarding my risk of exposure if the guy was positive?

(2). I read that the new guidelines are to have a 3 dose medicine of Raltegravir (Isentress) 400 mg PO twice daily plus Truvada (tenofovir DF 300 mg/emtricitabine 200 mg) 1 PO once daily.

However, I was only given truvada. Is that enough?

(3). How accurate will a fourth generation test be after 28 days? Will the face that I'm taking truvada give a possible false negative?

Thanks.

Answer

Hi there,

Thanks for writing in.

The risk for receptive anal intercourse is about 1 per 71 incidents. However, since the incident was extremely brief and was a one-time occurrence the likelihood of transmission would be much lower. For more information on the risk of HIV transmission by route check out this link.

Truvada alone is not enough for PEP, but is the prescribed regimen for PrEP which is taken every day as a form of HIV prevention. I'm not sure why they would have only prescribed Truvada for PEP. It might be worth contacting the clinic for further information.

By 28 days, most people will have produced enough antibodies that can be detected by a test. A follow-up test at 90 days will provide you with a conclusive result. If you received a negative test result at 28 days or later I would expect a negative result at 90 days as well. The Truvada will not impact your test result.

I hope this helps.

In health,

Richard