Spoiler Alert! If you haven't yet seen the movie, Blade Runner 2049, you might want to skip this question.
Officer K (also known as Joe) ...
discovers that Dr. Ana Stelline is the daughter of Rick Deckard and Rachael Tyrell. Ana has a genetic disability that makes her vulnerable to infections so she lives in an environmentally sealed room 24/7.
She was not placed ...
in the environmentally sealed room at birth. She was actually placed in an orphanage (actually a child labor camp) that was very dirty. She was probably exposed to many environmental toxins and dangerous microbes in that orphanage.
How could she survive even a few years on an environmentally devastated world?
This seems like a plot hole. Am I missing something from her backstory?
...genetic disability that makes ... vulnerable to infections
that's what you're told, how do you know that's true?