The Fury book by Alexander Gordon Smith

Imagine if one day, without warning, the entire human race turns against you. Every single person you meet becomes a bloodthirsty, mindless savage, hell-bent on killing you - and only you. Friends, family, even your mum and dad, will turn on you. They will murder you. And when they have, they will go back to their lives as if nothing has happened. The world has the Fury. It will not rest until you are dead. Cal, Brick and Daisy are three ordinary teenagers whose lives suddenly take a terrifying turn for the worst. They begin to trigger a reaction in everybody they meet, that makes friends and strangers alike want to tear them to pieces. These victims of the Fury - the ones that survive - manage to locate each other. But just when they think they have found a place to hide from the world, some of them begin to change ...They must fight to uncover the truth about the Fury before it's too late. But it is a truth that will destroy everything they know about life and death.