All the Devils Here

Brie Hall, a sheltered and privileged teenager, is in her final year of boarding school in New York City when disaster strikes. A worldwide biological crisis, the origins of which are unknown, quickly decimates a large portion of the population, and there is no known cure. The threat of contamination is always present, and she cannot trust anyone she sees on the road, and as time goes on, she sees fewer travelers.
While journeying to find her family, Brie meets another wanderer, a girl with a past she can't or won't divulge. Circumstance force them together to escape notice of government-issued hazmat vehicles sent to deliver them to unknown conditions. With no hope of a cure, they do only what they can to survive and remain free, picking up new skills and hardening into people they never meant to become. While struggling to answer the question of how to survive a plague, they must also ask how they can survive the version of themselves they've become.