The 1950s version of Invasion of the Body Snatchers was a thinly veiled allegory about the horrors of communism. The alien race in The Host almost parodies this fear: Oh my god, Everyone gets along fabulously! How can this be? They don't even need money! "Everyone who participates gets a medal now" (29.72). Our worst nightmares have come true!
We hate to say it, but, aside from all the humans being dead, the world seems like a better place.
Being an alien herself, Wanda totally buys into the whole "community" part of communism. When she's basically a prisoner and slave with the humans, she says that "The part I really minded [...] was all the taking without giving anything back. [...] I took what I needed and nothing more" (47.45).
So it's a good thing then that the new human colony, run by Jeb, pretty much operates exactly the way that the alien community does. People take turns performing all duties—cooking, cleaning, farming—and share all the spoils that Jared gets on supply runs. They would be just like the aliens if they actually got along with one another and had better healthcare.
What other parallels do you see between the world of The Host and the red scare?