Im the KING of worry warts, .......but of my 4 MACS,........nope, not worried ONE bit, nor should I be. Same for you as well.
Mac or Windows, however, ....there are only 3 diff. Harddrive MFG. (though your AIR uses solid state drive) , .....they all fail....backup your data religiously, not for worry of any VIRUS, but for sake of the 'nature of the beast', that being HD storage (HD or SSD either one) can eventually fail/ crash......
Should you worry about any Virus? ......NO
If this changes, this post will be updated. According to noted computer virus expert Paul Ducklin, in order for a virus to be considered in the wild, "it must be spreading as a result of normal day-to-day operations on and between the computers of unsuspecting users." This definition excludes "proof of concept" code that is used in a testing situation under strictly controlled conditions, and which poses zero threat to average computer users.
In the past, there have been a few viruses that ran on older versions of the Mac operating system (Mac OS 9 and earlier), but they do not run on any version of Mac OS X. Like every other OS, Mac OS X is not immune to malware threats, this situation could change at any time, but if a new virus is discovered, the news media, forums, blogs, etc. will be instantly buzzing with the news.