To run a virus from the Google market…
which there have only been a few, and the second they were reported they got pulled immediately; In an open source community information will travel exponentially faster than a virus, so bugs will often be exposed through channels of communication long before they actually spread
…you would have to:
1. Grant Permissions
2. Download it
3. Install it
No virus could be run from the market without you, the user, giving it privalages to do so first.
To run a virus obtained from an out-of-market source, you, the user, would have to:
1. Download it
2. Enable Installing apks from ‘Unknown Sources’ in your application settings
3. Install it
For any virus to modify/corrupt anything on the system level, you, the user, would first have to:
Grant Superuser Permissions
To protect yourself from viruses:
Stay away from browsing and downloading impulse apk’s from any third party site/market.
Only download apk’s from third party sites that you TRUST.
Only download Adobe Flash Player from the market and obtain all flash player updates from the market.
NEVER download and install a video plugin through your web browser or even within ANY trusted web based apk like Facebook or G+
Pay attention to the permissions you are granting to apps through the market, but don’t live in fear of market apps.
Pay CLOSE attention to which apps you grant Super User Permissions to and what they are doing.
Stay informed, which is very easy considering you are carrying a mobile computer in your pocket.
And for ALL platforms the most important rule is:
** ONLY download/install files from a TRUSTED SOURCE **
If you follow these guidelines running antivirus software on android is superfluous and will only be at the expense of slower system performance and faster battery consumption. Common sense and a little discretion go a long way. Enjoy your android device.