Unknown antibody titer - any risk?

I’m a hep carrier with an undetectable (< 10 IU/ml) viral load for almost one decade, thanks to the medication (Viread before and now Truvada with added protection against HIV). I recently started dating a new partner, who knows my condition and doesn’t feel concerned at all. He was vaccinated as a newborn and told me his antibody was confirmed (but probably not quantified) about three years ago. Since then, we never felt any concern to be very intimate with each other. We haven’t had any anal sex, but we have had deep kissing and oral sex. He might also accidentally used my toothbrush a couple of times (without noticeably visible blood but likely some microscopic trace?). We also share shower towels and nail clippers, etc. Frankly, once you start dating and live together a few days per week, some minor blood/body fluid contacts are quite difficult to avoid.

It only recently came to my attention that the antibody titer needs to be quantified and ideally more than 10 to be considered fully protective.

So, do I have to feel concerned? Frankly, my specialist even told me that I simply can’t pass it to others if my viral load remains undetectable. However, I sometimes have OCD towards some minor risks. Just want to get the opinions from the experts here if I’m overthinking. If the risk is like 1 out of 10000 or “virtually zero”, I guess I can live with it.

With undetectable viral loads and your partner being previously vaccinated, the risk of transmission is very, very, (very) low and not something to worry too much about. Your specialist is likely correct, though scientifically I don’t think these experiments have specifically been tested to be 100% sure about saying this (though there is circumstantial evidence to support it).

If your partner has previously been vaccinated, it shouldn’t be an problem, but it is standard practice to check antibody titres.

With your levels, microscopic levels of blood on probability do not contain any virus → 0.1mL is quite visible (think a large drop of blood) and your tests show you have less than 1 virus in that.

Hope this helps,
Thomas