My vampire Sim is a doctor and have this problem too - among many other problems with the doctor career. My vampire does not care if he is mean - he has the mean trait so I assume he rather enjoys it! He can do the hallucination thing which keeps them out of the way for awhile - or command them to sleep, sit, or leave - one nurse sat right on the ground where she had been standing and my Sims butt was right in her face examining the patient! It really does not matter if they leave - they don't do anything but get in the way anyway. I have also reset them and that helps. Usually, I just avoid the patient that the nurse stands by - plenty of other patients!