A 26-yeаr-оld wоmаn is newly diаgnоsed with early HIV infection. She is believed to have acquired HIV approximately 4 months prior from a brief sexual relationship with a partner who frequently injects methamphetamine. She has a new boyfriend and they have regularly had vaginal sex without using a condom during the last 3 months. She is asking how likely it is that she has passed on HIV to her new partner.