[Fishing-guy]

What kind of flu is it that one is gone in a day?
Did they ever explain it (of course, they have also not explain the origin of the zombie virus)?

[ConjunctionJunction]

On the Talking Dead executive producer Greg Nicotero said the this flu is modeled after the 1918 flu pandemic. So, we can probably expect the primary targets of the flu to be previously healthy young adults (I would think mostly in the 20-40 age range).

[Farnsworth]

Kirkman said in an interview that he wouldn't give an explanation for the zombie virus.

But never say never??? A companion series is in the works for TWD, to be released 2014-15 time frame, possibly a prequel???

[virgil283]

'The Walking Dead' Season 4 'Isolation' clips reveal who is already infected Did they ever explain it (of course, they have also not explain the origin of the zombie virus)? this might be a clue ..