Is it possible that the real ending will be based on if Jae or Ji Hoon found the ALB vaccine? I found 2 with Jae and 1 with Ji Hoon. I know it just dellays the effects of the virus till they get the real one. In some episodes I found the vaccine and those episodes have a green borderlining while some have a red version of it. The red ones as I noticed I couldn't find the vaccine till the end. In the red borderlined ones I also passed out near the ending of the chapter. I don't know if its inevitable or because I didn't find the vaccine. I added a picture with a red borderlined episode as an example.