Thank you for the answers.
I thought virus couldn't get through a format. I now understand it can. That makes it difficult to get a safe
So what if you fill up the usb stick with data files after deleting the usb stick? That won't work, because
the virus can be written in a way, so it actually doesn't get overwritten?
To clearify, I'm not asking this quistion because I suspect I have a virus problem on a usb stick. It was
a general question, whether you can make a usb stick, that you reason not to trust, safe again.
But it seems you can't.