Okay I don't know if this is a smart question and I found this answer here How do I clear everything (data, viruses) from a thumbdrive?, and didn't understand it fully. I thought formatting a drive was enough to get rid of all data.

I used my usb drive in a computer that is clearly messed up. So when I got home I formatted it, and then did a scan (it's Ubuntu but I have avast installed) to make sure files transferred between my desktop and laptop are clean, and well there wasn't much to scan seeing as I just formatted it, but I understand that apparently you can have hidden files and stuff still?

The scan doesn't show anything when I click show hidden files and it also says that its only using 4.1kb; it always says that; I'm guessing that's for something.

So Question 1, is it possible that the virus is still there?

And Question 2 if formatting does clean a drive, although it's Linux, would it have infected it, like the way someone can be a carrier of a cold and not be sick.