People refer to the infected as "zombies" although that's not what they really are. The word zombie implies the infected have died and reanimated. The thing is, those infected with Mad Swine, they didn't die. They're still alive; they even breathe. They're just not human anymore. No one really knows how or why it started. What we do know is that the H1N1 virus - or the damn vaccinations that everyone so anxiously lined up for hours to get - mutated in a bad way. Now whether this mutation happened naturally, like the seasonal influenza does every year by changing its signature protein, or if it was the work of some mad dictator bent on bringing hell into the world by unleashing the bastardized disease, no one can say for sure. For Matt Danzig and the small community of Randall Oaks, the only thing that matters now is survival in this new world.
