I've never been much for the theory that horror films "reflect social anxieties." I think horror has other primary appeals, such as its "sense of wonder" (something by no means exclusive to science fiction).
However, someone has crunched some box office numbers and TV ratings, and has concluded that vampires films are more popular during Republican presidencies, whereas zombie films are more popular under Democratic presidencies.
S. Peter Davis theorizes that this is because conservatives/libertarians perceive the Left as vampires, whereas liberals/progressives see the Right as zombies. And each of these groups, when out of power, suffer greater "social anxiety," which is reflected in the horror films released at that time.
It's a amusing article. Even better, Davis cites my book, Vampire Nation, as proof of his thesis.
Read Davis's entire article.