All that's left in the world / Erik J. Brown.

When the Superflu wipes out most of the population, Jamie finds himself completely alone in a cabin in the woods, until an injured stranger crosses his path. Life is dangerous now and, armed with a gun, Jamie goes to pull the trigger. But there's something about Andrew, something that stops Jamie in his tracks. Jamie takes him in, and as Andrew heals and they eventually step out into the strange new world, their relationship starts to feel like more than just friendship. But trouble isn't far behind. As the boys make a perilous journey south, they'll come face to face with a world torn apart and society in ruins. And who, or what, will they find waiting for them at the end of it all?