This is a one-sitting read. SICK is fast paced and action packed. I LOVE Brian and his tough, mohawk wearing best friend, Chad. After a virus spreads through their town, they end up stuck in the theater department with a few of their classmates. The main problem is staying away from the very violent killers outside of their portion of the school. The second problem is, Brian is separated from his younger sister and girlfriend, Laura.
We see a TON of violence as Brian and Chad, along with the theater kids, fight their way through the zombies in their attempts to rescue the two girls and eventually escape the confines of the school grounds. (They are locked in with a HUGE metal fence)
THIS IS NOT A TEST by Courtney Summers would be a good pairing with SICK. Both books involve a group of students trapped inside a school avoiding dangerous zombies and deciding whether or not to attempt escape.