Don’t worry about a positive. I’m a .56 positive and they will still administer even at a 1. The concern is that JC can cause PML. That is very serious. But they do the liver enzyme panels and blood checks to keep tabs on that. According to my doctor, within 1 month they can detect the formation of PML getting started and take you off it so it doesn’t develop . Even people with negative JC can still get PML.

Hopefully this helps.😊hang in there!