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What is the success rate of PEP in preventing HIV infection?

This Premium Q&A, reviewed and published, features a real conversation between an iCliniq user and a physician.

Patient's Query

Hi doctor,

I am a 28-year-old male and had unprotected anal-vaginal intercourse with a sex worker, with me being the active partner. I was put on PEP immediately, within 11 hours post-exposure, and the first dose of PEP (Post-exposure prophylaxis) was the tablet TLE (Tenofovir or Lamuvidine, or Efavirenz), given to me in the morning.

I was asked to follow up the next day with an HIV specialist, and she changed my PEP regimen to a combination of Tenofovir or Emtricitabine and Dolutegravir, as they are more effective. As I was worried and had a fever for two days, I did an HIV PCR (Polymerase Chain Reaction) RNA (Ribonucleic acid) test, qualitative exactly after 10 days from exposure. The results came back as 'not detected'.

Kindly guide.

Answered by Dr. Kakkar

Hello,

Welcome to icliniq.com.

I have noted your concern. Perhaps your question was not completely typed. Anyways, your PEP (Post-exposure Prophylaxis) regimen of Tenofovir or Emtricitabine and Dolutegravir is the recommended one. Continue with it for 28 days. As far as the HIV PCR RNA test is concerned, it is not a reliable test while on PEP. You need to wait for your PEP to be over before testing.

I hope this helps.

Thank you.

Patient's Query

Hi doctor,

Thank you for the reply. My entire question was not submitted, though. I have completed my PEP today. What are the chances of contracting the virus from this single exposure? I asked the partner to get tested, and she did it after a couple of weeks. She told me that she was negative, though I have not seen the reports. And since I started PEP within 11 hours post-exposure and complete adherence to it, what is the success rate of this PEP to prevent the infection?

Answered by Dr. Kakkar

Hello,

Welcome back to icliniq.com.

I would like to know if you are circumcised or not. The risk per act of unprotected vaginal intercourse with an HIV positive female is estimated to be 0.04 % (1 in 2500). The risk per act of unprotected anal intercourse for an insertive partner varies from 0.11 % or 1 in 909 (circumcised) to 0.62 % or 1 in 161 (uncircumcised). PEP is definitely protective, but it is not 100 %. In various studies, the seroconversion rates have been reported to be reduced between 50 to 80 % with PEP.

I hope this helps.

Please feel free to reach out in case of further queries.

Thank you.

Patient's Query

Hello doctor,

I am not circumcised, and moreover, if the PEP has been effective, I have also had an HIV ELISA (Enzyme Linked Immunosorbent Assay) 4th gen test done today. So, will a negative result conclude or do I have to wait for another test to be conclusive?

Answered by Dr. Kakkar

Hello,

Welcome back to icliniq.com.

For a conclusive result, you need to test at four weeks after completing PEP and again at three months after completing PEP. Do you have any symptoms? As far as the HIV test of your sexual partner is concerned, are you sure she has had no other recent sexual partner after you? What was the test that she did?

I hope this helps.

Thank you.

Answered byDr. Kakkar

Medically reviewed byiCliniq medical review team

Published At January 24, 2018
Reviewed AtDecember 30, 2025

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