I got a hit from a Bugbear and my Norton (within 5 days of the last update) missed it. Fortunately I have a policy about attachments and files with extensions I don't understand so it got wiped summarilly. Then a Mudcat alert and a Norton update - fast. The next three hits were all found by Norton. So there was a window between where Norton were finding the problem and posting fixes.
Mind you I have switched off all scripting in my e-mail client so maybe that saved me.
I KNOW I would struggle with an infection and the thought of it keeps me vigilant.
From what I am told Norton have the answers but the proceedure is not always that simple. Best of luck - PAL.