Kai's Journey 1; New World Chronicles

Kai is twelve years old when his father, trying to create a superior breed of soldiers, unleashes a disease the world has never seen. It soon becomes an epidemic, triggering unsurpassed chaos.
In the aftermath, Kai meets a young woman named Clover, and together they try to find what is left of humanity. More surprises a wait as their journey takes a turn, fueled by the increasingly dim hope that somehow the human race will have a chance to start over.