I don't care if I "catch hell" for replying seriously to this guy's post...
so here goes.

Personally, I think that not only is there a direct relationship, but that the relationship "swings both ways" so to speak.
The fear of "foreign invaders" (i.e. aliens, Germans) had a direct impact on the genre filmmaking of the late 1940's and early 1950's. The fear of "commies" (i.e. pod people, etc) heavily influenced the genre filmmaking of the late 1950's and early 1960's. WWII, followed by the "cold war", followed by the Korean War, followed by the Cuban Missile Crisis, followed by the early stages of the Vietnam War, followed by the official end of the "flower child" era (as indicated by the Manson Family murders of Tate, Folger, et al), followed by the later years and end of the Vietnam War, etcetera, etcetera, ad nauseum...
Any of these events can be written on paper and picked at random out of a hat, and then directly associated with a film or films that perfectly encapsulates the nature of the widespread fear directly associated with that given event. Obviously, like others here have said, the issue has been beaten pretty severely...but IMHO not quite to death. This is an issue that will never actually die. If it were to die, then genre filmmaking at large would die with it. The goal, I think, is to try to stay one step ahead of those fears...or perhaps one step behind. Nowadays, to purposefully inject "social commentary" or reaction to "current events" into a horror film is not only "frowned upon", but it's looked upon as being (gasp) pretentious and manipulative.
There have been books written, posts posted, theses explored, and discussions aplenty had about this very issue...but only because the issue is always timely...always valid. So, to stand behind the position of "it's been said before" in this case just ain't valid...it's a cop out. People will always look for meaning in their favorite films, books, etc because it's part of human nature to do so. We search for reflections of our fears in the activities we take part in during our "off hours". That helps us deal with our fears.
Anyway, like others have said, "It's been said before"...
But that doesn't mean it's any less true now than it was during the cold war...

I would recommend reading the first half of Stephen King's book "Danse Macabre"...wherein King offers his perspective on this very issue (at length, I might add).
Good luck on your paper, and don't worry about the people who criticize your choice of subject matter. You might not bring anything new to the table in your paper, but you'll at the very least continue the fine tradition of talking about horror films from a relevant-to-society perspective. And that's the point of "horror movie forums", is it not?
Cheers...