I'm still JC negative, but I'll tell you my mind is already made up if/when I become positive. I take Tysabri and would continue to take it. While PML is a risk, it really is a small one. Is it scary? Of course, but the risk is low, particularly when compared to the benefits of medication. I've lived with a grandfather who had this disease, I've seen what it can do without a disease modifying treatment, it's far scarier than PML. I also consider Tysabri a literal life saver for me. I honestly don't know if I'd be here without it. Far too many people get overly worried about PML, without worrying about the consequences of MS itself.