Zombies are, in fact, real, though not how you would expect. Zombies are a form of taboo that kills a person, then brings them back to life later with a weaker and more decayed mind. The most reported kind of this taboo is the use of zombies as slaves, though who knows what else they are used for. Also, the US military has actually mutated a flu virus and mixed it with rabid, both for a higher infection spread and to make it a killing machine. They, however, soon erased the program and only used the virus in Afghanistan in order to learn more about combating the virus and training certain people in counter zombie operations, mostly at the fire-team level, though sometimes higher. We don't have anything to fear though, because it would be a war crime to use this outside of training to combat it, and the US would have to erase everything related to the program or go to war with the world. The US would probably be brought down before they were able to use it on a major scale, and I doubt that that the US wants that.