i had 10 humans in one building all armed and killing zombies until one was stupid enough to walk out the front door and let the zombies in right after they slaughtered him in about 5 seconds
i had the minimun number of humans and the minimum number of police and the maximum zombies the humans lasted for 10 minutes then the were backed into a building surronded by zombies and quickly picked off
wait for your evolution points to reach at least 1000 then buy all the ways for it to be transmitted and all resistance and get rid of all side effects it will take longer for them to notice and they wont take action for a long time because it does nothing