So what I assumed happened was after getting rescued, she had to talk to the ones decontaminating her about her wounds, and why there is an injection sized hole on her arm.
Then after explaining that, she'll explain that she's a college student with knowledge with scientific bacteriology or what not. Get's accepted into the research team but because they could not find the right antibodies for as a cure from only blood samples, she offered her arm for research.
12 years pass, she somehow pseudo-graduates with a degree within walled territory and is now a head/lead/major contributor to the cure and is now leading the revival project. In that time, she secured You-kun and made efforts to make him the first recipient of the new revival drug.