YA subterranean fiction (I believe) where the main character had to leave because of some danger in his bunker. Read 2014-2016. Spoilers ahead.

[Ryan]

I read the book between 2014-16 and I remember only a few details. I remember they were in a bunker or a facility to protect them from outside. I also remember the main character was forced to run away because there were people either raiding them or planning to. After he ran he found 2 people there was one man with a sniper that he used the scope of to scout for people and one girl I dont remember what she did. I think there might have been some disease they were worried about that changed peoples color and killed them after like 2 days or something like that. The only other thing I remember was that the bad guys captured the guy with the sniper at some point and strung him on a cross and then beat him or something like that and they were too scared to go get him, if any of you know this book please let me know and thanks in advance