*sips coffee*
How it goes down:
Firstly, Simian Flu has come and gone, intelligent apes are extant and on the warpath. Secondly, the genetic virus from Black Sheep was been widely spread and Were-sheep/Were-sheep humans abound. Thirdly, the classic Romero walking-zombie outbreak has occured concurrently with these alongside the Rage virus from 28 Days Later.
The last ten or so humans are hiding out in a bunker in Antartica, living off penguin meat. They shouldn't even register in this clash, but you can consider them if you like.
So, how do you think this plays out?