I haven't heard of being positive then negative for JV virus. I was on Tysabri for 4 years and was always negative for JV but recently converted to positive. I believe it is still safe to be on for a year after converting but then you must come off. I am going to start the new treatment, Lemtrada in March. It's a 6 hour a day infusion for 5 consecutive days but that's all for the year. The Second year it's 3 days then nothing else ever! I'm excited!

people have a tendency to overreact To JC virus situation. As far as I know there was only one or two people in the history and had a problem with it.a year ago I was tested for the JC virus and I came out of .22 and 6 months later it went down to a .19 and this is after taking Tysabri for over 5 years.and being on Betaseron and Avonex before that.now my numbers are very very low.I've heard of people taking Tysabri even when their numbers are about 2.0 and higher. it has stopped my MS dead in its tracks.I needed to get on something very fast because the MS was tearing me apartand I went on this medicine and it was very successful.I just wish I coulda went on a soonerI would still be walking

and no you cannot be positive then negative. I suspect a false positive or false negative at the lab

I too am JV + & had to go off Tysabri after being on it for 6 years. Life is just not the same since going off Tysabri. I'm on 3 day Copaxone & not liking some of the side effects, like increased fatigue & weight gain. But couldn't tolerate the new orals. Got to do what you need to do to fight this disease.

They do have ways to fight PML now so if you do get it, it can be slowed or stoped.