Bacilli by A.P. Foote

The world fell apart faster than anyone would have thought.

Not from nuclear war, or famine. No, the military was messing with things that should have never been tampered with. No one has the right to play god—or hire biochemists and virologists to create weapons.
But they did, and in doing so created a lethal virus that is wiping out the human race in some form or another.
They never intended for them to get out, for things to turn catastrophic in the matter of minutes, but it happened, and there’s no going back.
My name is Billie, and the military took something of mine. I will do anything—and WILL—to get it back. My immunity is the key to survival, and the Experiments extinction. But who is the real danger? The Experiments? Or the other Survivors.