Contagion — Sarah Hall

Two childhood friends are separated from each other during a cataclysmic upheaval known as The Uprising that has spread a rabies-like virus across the face of the world, turning humans into bloodthirsty beasts known only as 'virants.' Many years after the virus known as the Index Contagion tore through the world and decimated the earth's population, Julian Sykes, the son of the virus' foremost researcher, embarks on a quest for revenge against the shadowy man named Rybeck who murdered his father. Unbeknownst to him, his childhood friend, Sasha Kite, is Rybeck's second in command, the leader of a desperate group of survivors known as The Enclave. When Kite and Julian finally meet bonds are tested and blood is shed - for in the ruins of the new world knowing who to trust is the only currency that matters.