Dr. Bob, i'm really worried. mt girlfriend is hiv poz. been poz for 4 years. i am neg. her viral is undetectable. about 3 weeks ago now we were having sex, she was on top. when she goy up we noticed that the condom had came off. she says it was when i pulled out. i really don't no how long it was off. i'm now really scared that i might have been infected. could you please give me the odds of getting this. we try very hard to practice safe sex. thank you so much. and a donation is on the way.

Hello,

If the condom slipped off as you pulled out, your sexual activity would still be considered "protected." If, however, it came off sometime earlier, your risk would be the same as "unprotected" insertive vaginal sex with a positive partner. That per-episode estimated risk is 5 per 10,000 exposures. If you are unsure, get tested at the three-month mark. For future reference, if you do have an accidental significant exposure, PEP (post-exposure prophylaxis) medications are available. They should be started as soon as possible and no later than 72 hours after a potential exposure.

Stay well.

Dr. Bob