I saw an infectious disease doc today and he has ordered CMV by PCR. The problem is I've been on 450 mgs Valcyte for 3 weeks. I did not tell him at the appointment but he would be ok with it because he said he will support my taking if I got it elsewhere if the labs don't show any CMV in my blood. My question is, could 3 weeks of 450 mgs change the levels of CMV in my blod, and if yes how long should I be off to get an accurate test? I'm probably going to tell him tomorrow, I just want some info first. Please TAG me so I get an alert.