Any Disease Modifying Drug (DMD) is "damping down" our immune system to stop it attacking our myelin sheaths, so it can leave us vulnerable to other infections. Having Googled "Tysabri and Shingles", there is a fair bit of information. Here is just one thing that I've noticed:- "Before you receive each infusion of natalizumab, tell your doctor if you have a fever or any type of infection, including infections that last for a long time such as shingles (a rash that may occur from time to time in people who have had chickenpox in the past)." So, do contact your MS Nurse to update them and also call your infusion centre for further advice.

Thanks. Yes, there does seem to be quite a few examples of other people experiencing the same. I've spoken to my nurse (well, texted) and she doesn't seem overly concerned, but I'll speak to her properly in the week. Thanks for your reply - it's just yet another thing, hard to stay positive sometimes but there you go.