Mainly on newround. But it does happen randomly but mainly when a new round starts.
Anyways...
Haven't tested the new version yet but heres some suggestions from me.
Have a cvar of how long you have until you turn into a zombie when you get hit by one. Because I don't like the fact turn into a zombie straight away when you have just been hit. And maybe some sfx while he is changing into a zombie like his screen goes red and shakes like crazy then POOF. Green nightvision with zombie hands.
Threaded Mode