Hi All: I have been on Tysabri since Mar. 2011. Got result of postive for the JC virus in May and Neuro started me on Tysabri every other month. Medical carrier was Aetna at that time, now I'm on Medicae effective Sept. 1. Medicare is refusing to pay for infustions every other month, they WILL cover them every month. I understand that every other month is not following prescribing info from Biogen Idec, but, it saves them money if I go only every other month. My neuro now wants me to go back to every month and I'm not sure I want to due that based on the JC virus and numbers I see listed on the internet for PML and JC virus. I would love to hear from positive JC and on Tysabri patients and also from people with MS on medicare and how they have had the drug covered. Thanks all, Pat