I'm confused - according to that data...
... 20,200 people in the US are on Tysabri and 16,900 outside US.
BUT: There are until now 5 PML cases (Tysabri mono therapy)
1 in the US
4 in Europe (out of the 4 there are 3 !! Germans)
What is happening? Better screening for PML risk candidates in the US? Higher JC virus prevalence in europe?