There's no sense crying over every mistake,
you must keep on trying til' you run out of cake
and the science gets done, and you make a neat gun,
for the people who are, still alive.
Oh yeah, during one of the missions after you get curbed stomped by Krancenko a zombie will come out and bite his ear off. After that, you escape with 3 other people to a zombie invested resort in cuba, those 3 die in a mere 3 minutes, and you have to escape, ALIVE!
After that, you meet up with Dempsey, Rictofan, Toakeo, and Nikolia but Nikolia shoots you because he thought you stole his vodka.
tl;dr: No zombies are in Campaign and i have NO CLUE why i just typed all of that...