The Girl with All the Gifts by M. R. Carey
A fungus wiped out most of the population and turned those in contact with it into zombies. A few other "off the grid" humans managed to survive, but would fight against other groups. There were also some military groups that survived and are studying it in a lab. They are studying some kids that have been exposed to the fungi, yet still function as normal humans. The lead researcher is portrayed in a negative light throughout the book. This sets up the conclusion where they realize the best course of action is to let the funga do a massage spore release that will wipe out the current state of humanity and lead to a future human/fungi symbiosis. The narrative flows very well and stays interesting, even as it presents a non-standard conclusion to the post-apocalyptic zombie tale.
