Hiv/aids What Are The Chances Of Catching HIV/AIDS From Someone That Doesn't Have It By Anal Sex Without A Condom?

What are the chances of catching HIV/AIDS from someone that doesn't have it by anal sex without a condom? - hiv/aids

Me and my girlfriend had anal sex without a condom may be a week ago. Until now I did not know he was so dangerous.
What are the chances of me contracting HIV / AIDS, that although we both HIV / AIDS negative, because we had never had sex.