I'm gonna struggle a bit here and say some good things. The writing is clear. The characters are easily visualized. The plot twist is serviceable. 
 It's not a bad book. There's plenty of tension and action and *big* *fear*. 
 But? 
 Yeah, well, um... I'm read it before. A lot. 
 But it's YA! It's meant for new readers who've never been blown away by classics like Darwin's Radio or The Children of Men or any of two out of three dystopian YA novels on the market. 
 Add cute girl and two cute boys, give her talent and drive, cut and paste into a slightly different dystopian future filled with almost everyone dead, add supersoldiers, mix, then a reveal. Sound familiar? That's because it's formula. 
 Powdered milk with a bit of mineral fortification. It kinda misses the whole point of having a bunch of thriving gut flora and leaves a child's mind weakened to truly invasive memetically-modified horrorshows that will change your life. 
 Again, it's pretty standard stuff. It's okay. But it won't change anyone's life.