Windows Phone need virus protection?

I recently purchased my first smartphone, a Nokia Lumia running Windows Phone. I've been looking for an app or software for virus protection but haven't found anything suitable? There seems to be a lack of smartphone security apps, why is this? With increasing use of mobiles for all sorts of uses I'd have thought this feature would be a priority? 

Vigilance is commendable but as yet there hasn’t been any real threats to Windows smartphones. They are still relatively new with a tiny market share, which makes them much less of a target for viruses and malware. Like the iPhone, Windows Phone is protected by a ‘walled garden’ App Store with a tight screening process designed to weed out apps carrying a malicious payload. That is not to say that something won’t slip through the net and security loopholes will be uncovered in the future but for the moment the biggest threat to Windows Phone users is fake alerts and scams that scare you into thinking that your phone is infected and trick you into parting with your credit card details for useless, and usually non-existent anti virus software.