I had 2 brief exposures with no ejaculation. Vaginal penetration (I am the woman) neither lasted more than a minute. I started PEP within 24 hours of exposures for 30 days. Somewhere in the middle of the regimen I missed 2 doses unsequentially (missed a dose once and then maybe a week later missed another) 

I tested negative with RNA test at 14 days post last dose of PEP. If I were to test at 41 days and 13 hours (post pep) with 4th gen test would this be conclusive? Or is it better to wait until the complete 42 days (post pep)? What are the odds of testing negative? 

Thanks. 

Did you have reason to believe your partner(s) is/are at high risk for HIV, i.e. gay/bi men, IV drugs users, immigrants from Africa, etc? (It isn't clear whether both events were with the same or different men.) If not, I would have considered your risk of HIV too low to warrant PEP, given the continuing rarity of HIV in heterosexual men without such risks. That doesn't mean it was wrong to take PEP -- even when the risk is low, there can be tremendous value in the increased reassurance that may come with PEP. 

Before taking PEP, I would have estimated your risk of having acquired HIV at under one chance in a million. (I'm happy to give you the basis for that guesstimate, if you would like.) PEP taken within 24 hours probably is at least 90% effective in preventing HIV infection, so that brings the chance you have it down to something like one chance in 10 million. And probably 90% of newly people infected despite would have a positive RNA test at 14 days. So now we're at one chance in 100 million that you have HIV.

Conclusive data to not exist on time to conclusive HIV antigen-antibody (AgAb, 4th generation) testing following PEP. Six weeks (42 days) probably covers it, but some experts advise even later testing. There is no significant difference between AgAb test reliability at 41 vs 42 days. So I would say there's at least a 99% chance your anticipated negative result would be accurate. So now we have arrived at an estimated chance you have HIV of one in 10 billion. I hope you will agree that's zero for all practical purposes! You probably are at higher risk of being struck and killed by a meteorite someday!

So all is well. You can be entirely certain you do not have HIV. If you go ahead with an AgAb test at 41 days, you definitely can expect a negative result.

My only other comment is that your don't mention other STIs. Your risk of gonorrhea, chlamydia, or syphilis was far higher than for HIV. I assume (and hope) you have been tested for them, with negative results. 

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

HHH, MD

To be clear the only test I’ve had done is the 14 day RNA test. I’ve yet to actually take or receive results from a 41 day Ag/Ab test as I’m still waiting for that day to come. But from your comments I can assume there is a very good chance it will be negative? 

And if it is can I stop testing or would you recommend further testing as you say some experts do? 

Sorry if there is any repetitions as I am quite nervous about this situation. 

I correctly assumed you had only had the RNA test and that you were waiting to do the AgAb test. But I have to wonder why you would do the AgAb test at 41 days, which is one day early. Why not wait the additional day? In fact, the actual interval recommended by CDC is 45 days:  on this forum, we round that to 6 weeks or 42 days, knowing there would be no significant difference. Still, perhaps you would feel best by waiting until the official CDC interval. Whenever you do it, indeed you can be 100% certain it will be negative. I have never heard even a rumor of someone with negative RNA 2 weeks after completing PEP who later turned out to have acquired HIV. You won't be the first!

The whole idea of all my comments is to take away your nervousness! Really, there is no chance you have HIV. Please do your best to believe it.

And if it’s better to wait until the complete 42 days have passed I will do so, it’s just on calendar I always count the days but I forget that since my nightly PEP dose was at 11 pm that I have to wait until that hour has passed to be a complete day.. if that makes sense. Basically I’m impatient and nervous and want to know as soon as possible so I can hopefully move on from this.  But if 42 days is more conclusive than 41 then I will wait. 

I did also ask for proof of his status or to get tested (several times) but he refused and said he found it unnecessary. 

Also I’m not sure if you noticed but I did mention I missed two doses of pep. One was missed about a week into the regimen and the second dose missed 2 weeks into regimen. 

Now with the revised information of 13.5 day RNA test and 2 missed PEP doses do you still consider my odds to test negative to be significant? Thank you. 

Your partner's response to your request he be tested for HIV sounds reasonable to me -- depending in part, of course, on how you presented the issue. But I would take his response as a) entirely normal in the circumstances and b) evidence he doesn't have HIV.