I live in Korea and enjoy casual sex with masseuses, usually Chinese massage therapists, and occasionally Thai therapists. . At this point, due to my health anxiety, I have only partook in oral sex, and occasional condom protected sex. I want to ensure that I am as safe as possible. 

My questions are as follows:

1. What would be the statistical effectiveness of using both prep and condoms?

2. What is the prevalence of HIV in Chinese and Thai massage therapists?  The massage therapists are mostly in their twenties and thirties

3. Would you consider the use age of prep and condoms together to be almost 100% effective?

Is there anything else, other than prep and condoms that I can do to make myself even safer?

I would love to hear your answers and any/all advice you can give me to ensure that I am as safe as possible. 

Thank you!

My first general advice is to question your intent for pre-exposure prophylaxis (PrEP) against HIV. PrEP usually is advised only in substantially higher risk situations than seem to apply here. As discussed in your previous threads and I think you know, oral sex carries little or no risk of HIV, even without condom protection. In fact, there still has never been a scientifically well documented case of HIV transmission oral to penis. And condoms work very well in preventing transmission by vaginal sex; and even unprotected, the average risk -- if the female partner has HIV -- is one transmission for every 2,500 exposures. When we add the likelihood that your partners will not have HIV, your risk of HIV -- without PrEP -- will be very low.

Having said that, PrEP decisions almost always are best made by an expert who understands the local epidemiology of HIV, transmission risks, etc. As you undoubtedly know, (South) Korea is a medically sophisticated country, and you should have no trouble finding a doctor or clinic whose advice on all this will be more pertinent than anything we can say from this distance.

To your specific questions:

1,3. For oral sex, the risk of HIV is nil even without condoms. For vaginal sex, probably on average condoms reduce the risk of HIV by around 99%. PrEP is roughly equally effective. Their combined use makes the risk zero for all practical purposes. But for the reasons above, that risk also is zero for practical purposes even without PrEP.

2. I do not know the prevalence of HIV in massage therapists in Korea, regardless of their ethnicity. In general, in industrialized countries (including Korea, I would think) under 1% of commercial sex workers have HIV. As implied above, a local expert might have data on this. However, I suspect any such data would be for commercial sex workers -- which may or may not encompass massage workers.

I'm afraid that's the best I can do, but I hope these comments are somewhat helpful. Let me know if anything isn't clear.

HHH, MD