[Steph actually takes a second to think about that, turning over theories in her head.]

I dunno about this compound, I'm kinda willing to rule it as an outlier since, you know, it's where we woke up.

[So who knows what the heck is going on.]

As for the whole "zombie" infection, it could've been released into the air, or something in the water. Like a toxin that infected almost everyone at once.

[She's thinking Joker Toxin or Scarecrow's gas.]