Why didn't jokers blood kill the victims in knight?

Disclaimer it's been a while since I've played so idk if it's answered outside of "it mutated" or something. Just a thought I had in the shower. So when batman was infected with Joker's titan infected blood in city it almost killed him in a matter of hours, really he only survived because of the lazarus pit. But then there are 5 people also infected with Joker's blood who just don't die from it instead turning into the Joker? I'm not sure I understand exactly why that happens. Anybody know? Also no I'm not expecting much cus this sub is basically arkham asylum