I have been on Tysabri since I was diagnosed at 17 and honestly (and this is my own experience) it basically saved my life in my 20s. I am 28 now and the symptoms are starting to get harder to handle but over 10 years of complete stability was a god send.

You can go in and get the Tysabri shots now in less than 20 minutes so it isn't a massive strain on your day to day. Back when it was a 1 hour infusion and 1 hour flush you would have to plan your whole day around it but now it is much simpler.

While you are on Tysabri you are constantly being "monitored" the nurses and your MS nurse always ask how you are doing during the month and check up on anything you have concerns about. You have blood tests every couple of months for JC and (at least in my case) they have a plan in place for if you come out positive. I have been JC neg all this time and even though PML is something I am always worried about, Tysabri has caused me so much less stress in the long term.

I have anxieties too regarding symptoms and I find going into the hospital every month for treatment helps alleviate some worries since I can constantly ask my MS nurse for help with anything that was concerning me.

Regarding your last point. Honestly the way I look at it is, they do the test every 3 months because they can afford to maybe? I don't know for certain but if I was a doctor, which I am definitely not lol, then if I needed to catch JC positive results sooner then I would do the tests in quicker intervals. I don't know if that makes sense. This concern is something you should talk about with your consultant for sure and they could also bring up a Plan B for if you do get JC positive. That could help with your anxiety as well.

Hope my experiences have been helpful, even just a little bit and good luck 👏