I have been using "on-demand" PrEP from time-to-time and I had taken a PrEP tablet 3 days before the encounter, 2 days before the encounter and then again about an hour before the encounter.  So I missed the PrEP tablet the day before the encounter AND only took one tablet (instead of the recommended 2 for "on-demand" dosing) about an hour before the encounter (not the minimum 2 hours as recommended).  I did, however, continue to take PrEP for the subsequent two days as recommended as part of the "on-demand" regime.

Thank you in advance for your assessment and any advice you can share. 

Welcome to the Forum and thanks for your confidence in our service.  I'll be glad to comment on your questions.  Let me start by complementing you on your use of PrEP.  While the regimen you took was not the one which has been most widely studied, it is reasonable to assume that it would further reduce the already low risk for infection associated with the encounter you describe.  Let me provide some facts, followed by my advice:

1.  Your partner told you he was negative.  Most people tell the truth.  (I should add, that even if he was infected, if he was on effective therapy, he would be un-infectious as well).

2. Performance of oral sex on an infected, untreated partner is low risk. Even the U.S. CDC which tends to be conservative estimates  that transmission through receptive oral sex occurs less than in in 10,000 episodes. 

3.  You were taking PrEP which would further reduce your risk for infection. 

4.   Admittedly, you do not mention fever but your flu-like illness has occurred at about the time the ARS might occur.  When at risk persons with flu-like illness have been studied, only about 1% of them turn out to have HIV. The remained tend to have other flu-like viral illnesses.  You have been traveling as well which is a circumstance associated with risk of non-HIV flu-like illness.

My advice.  The chances that this is HIV are very, very low - statistically less than 1 in a million (risk from oral sex  X ~1% risk that your partner was infected X your on-demand PrEP) BUT transmission of HIV does occur rarely in this situation.  If you were my patient I would order an HIV PRC on you, anticipating that it will be negative.  When it is, my advice would then be to urge you not worry further and offer my best wishes that I hope that your non-HIV flu gets better quickly.  

I hope that this perspective is helpful.  EWH

 In my opinion your risk of being infected is infintesimal and not something to be worried about. If the problem is on your mind however, the most direct way to resolve your concerns is to get tested as suggested. If these are not concerns I would suggest no need for testing or waiting until six weeks had passed for testing  with a fourth generation test. 

Hope this is helpful?  EWH

(1) I know judging HIV risk based on symptoms is difficult but, in your clinical experience, is sore throat alone ever indicative of ARS? The muscle aches in my legs were definitely a result of my run and have now subsided; the tiredness is because of my lack of sleep. So I literally just have a bad sore throat. The timing and lack of nasal/cold symptoms is what is freaking me out; seems pretty coincidental it came on exactly a week after the event and I don't have a cold or feel particularly unwell.

Thanks for additional information.  Final responses below:

1.  The classical description of the ARS is a "flu-like" illness comprised of high temperatures,  sore throat, and flu-like muscle and/or joint aches, sometimes accompanied by diarrhea or a faint generalized body rash.  An isolated sore throat without the other components (you apparently have a satisfactory alternate reason for your muscle aches) is NOT the ARS and further greatly reduces the likelihood that your symptoms are due to the ARS.  I would add that when at risk persons seek care for a flu-like illness, 99% of them have the flu or something other than the ARS.  Thus odds are that your current symptoms are due to HIV are very low.

2.  PrEP was studied for HIV prevention irrespective of the type of sexual activity.  HIV following oral sex is so low that this could not be reasonably studied.  There just isn't enough data to comment further.  I would hypothesize that it would have at least some beneficial effect.

3.  Most oral gonorrhea and chlamydia or the throat is asymptomatic.  The only way to know about these infections is with a throat swab test.

Hope this helps.  As you know, we provide up to three responses per question and since this is my 3rd response, this thread will be closed shortly without further responses.  EWH