If someone who has HIV takes medication for long enough, and doesn't regularly miss a dose, they cannot pass the virus on. If both parties involved are otherwise STI free, they can have sex without a condom and are the HIV free party is not at risk of catching HIV. My partner has HIV and I didn't know about UU until I met him. It stands for 'undetectable - untransmittable'. Apologies if this is a well known thing, however am curious to know how many people are aware of this? Was told on a previous threat when I said my partner has an STI which is currently non transmittable that I need to educate myself about the definition of STI and that he is pulling the wool over my eyes. Interested to know how well known this is...