Viruses are a risk on any operating system. Human generated code can usually be exploited in some manner.
Android however has not been exploited in any major ways so far.
I can't guarantee the future but as of today Android is not a big target for viruses.
That may all change one day but for the time being I wouldn't worry about it.
+1
Any operating system is vulnerable. Apple claims they are not but they secretly released a OS X patch that included malware protection and avoided mentioning it in press releases because they want the public to think Macs are virus free.
The fact is as market share grows do will the need to compromise these systems.
The more private information is stored on these devices the more the need to collect data will become.
A misconception of malware (viruses, spare, highjackers) is not to kill your computer, but to collect data. Most malware would not serve their developer's purpose if the device if it just stopped working.