 The only four characters shown to definitely not get infected are Optimus Prime himself, Metroplex, the Quintesson, and Wheelie (who was mentioned, but didn't appear in the second part of the episode, because he was replaced by Blaster).The characters who only appeared in the early scenes which was before the plague and never got infected were The Technobots, the Terrorcons, Soundwave and Ratbat.The human survivors who are alive and never got infected by the plague were the doctors, nurses and patients from the General County Hospital where Jessica was taken in for operation, the police officers who helped the Autobots by trying to stop Superion, the civilians on the bridge where Defensor was trying to escape from Superion, Bonnie Carlson and some civilians in Washington, D.C.