BitDefender: Malware, It's In Your Face(book)!
To be fair, BitDefender didn't ping every user's news feed, 'just' 14,000 of them. That's still a significant sample, and if you're a glass half-empty kind of person, it's conceivable that the 20 percent figure is undershooting things (and if you sip from a glass half-full, it could be way too high once you analyze all 500+ million members).
Most of the infections BitDefender found were associated with apps written by independent developers. These typically promised some type of reward in order to get users to install them, so there's a big common sense aspect here in order to avoid falling prey to a holiday ruining infection.
If nothing else, let this be a reminder to surf safely, no matter what your online destination.