Internet Storm Center has some more discussion
The bottom line is Symantec has said its software products can only catch 50% or so of the viruses out there.
PCMag says so what: http://securitywatch.pcmag.com/security/323419-symantec-says-antivirus-is-dead-world-rolls-eyes
The comments gave a couple of good links(which I captured a couple of images from):
http://www.av-comparatives.org/comparatives-reviews/
http://www.av-test.org/en/news/
So one can test the Anti-Virus programs that are out there and realize the potential effectiveness. The reason Symantec is saying 50% effective, is that this is no longer a large business for them, and getting some quick headlines always helps.
There are a lot of AV programs, and in my opinion pick one that you are comfortable with, and then be aware of how to defeat a virus in case the new ones have been modified to such a degree that it requires some manual fixes.