Satire is any message in a work that's intended to shame people into better behavior. Good science fiction is satire. Science fiction has this special ability as a genre that can carry satirical messages because it can escape the gravity of our natural world.
I was always amused by George Romero's 1978 "Dawn of the Dead". Some contemporary critics were unable to look past the gore and script (which admittedly was incoherent at times). The foibles of a weak stomach include a causal link with adherence to tradition, fear of the unknown and resistance to new ideas. The parallel of squeamishness and ignorance is certainly to the detriment of the reviewers in terms of appreciating Romero's social commentary.
The zombie apocalypse "When there's no more room in hell, the dead will walk the earth" is the most obvious theme. I appreciate why this is an appealing plot device, still I found this theme somewhat empty as the end of days has been going on for about two thousand years.
The element of Romero's film that struck me was that even in death, we flock to the mall. Consumerism induces sensory overload fueled trance-like state in which our dulled senses cause us to devour the those around us in mindless pursuit of something that can't possibly nourish a body when it is no longer living.
Ironically this same drive to consume materials with no nutritional value caused our financial apocalypse. The living dead exist on unnatural terms and borrowed time. Does this sound like a credit card to anyone else? When the dead try to behave as though they are living or the uneducated seek to live as though they've earning the income of someone who has finished college, we're headed for something shocking and horrifying as society collapses into chaos. (I hope you'll also note that I draw a real appreciation for and ability to really live life in being educated.)
Zombie apocalypse or financial collapse, our only hope is to lay low and focus on surviving until the crisis passes and we can build again.