I do not think you have anything to worry about, as you have not been around him since his symptoms began. You would have already gotten it from his roommate if you were exposed to him a week ago. The only tips I would have are to wash, wash, wash while you're there and maybe offer to clean their bathroom, lol (with gloves and mask) if you dare. I did that for my boyfriend (well, now husband), and it was DISGUSTING. I swear he had never cleaned it since he moved in. Not sure I would recommend that one Lysol is always good! Spray away! And maybe not eat over there for a few days if you feel too anxious? Or maybe he could come to your place for a few days until you feel better about the situation? You should be fine!!