Hello, Thanks for posting in HCM. No it is not possible to transmit HIV by just having intact skin contact to infected blood. If you did not have any injury or wound where the blood might have contacted there is nothing to be worried of. What you must have got looks like an allergic reaction to something very recent you came in contact with. Try taking Benadryl one tablet and see whether rash comes down. If it doesn’t kindly consult your doctor to find out the exact reason for the rash as it might require expert examination of the rash. But do not be worried, HIV transmission through that blood on seat is extremely unlikely. I hope I answered your question satisfactorily. If you have any more query kindly write back to me, will be happy to help you out. Thank you.