Daybreakers

In 2009, a plague caused by an infected bat transforms most of the world's population into immortal vampires. The human population plummets, leaving vampires with a severe shortage of blood; vampires deprived of blood degenerate into psychotic, bat-like "subsiders". Most humans are captured and harvested in laboratory farms while scientists research a synthetic Substitute. As sunlight is deadly to vampires, underground passages and UV-filtered cars are built for safe travel, while the few free humans travel by day, hiding in open spaces.