In the intro cutscene (which I presume is supposed to be mostly, if not entirely canon) survivors have guns on top of the Vannah hotel. Which I presume they used to fend off infected. But upon starting up Dead Center and leaving the starting area the survivors act aghast. "Jesus Christ, what are these things?!" ~Nick If they supposedly fought the infected then why are they so surprised to see infected in the hotel? (Ignoring that Ellis and Coach's shotguns just disappear off the face of the earth)
i think that the parts that take place in other campaings are not cannon and maybe since they go there to get evacuated they didnt encounter that many infected and because the green flu is not well explained to the public nick asked about the sickness itself instead of the zombies