Originality is a big issue for authors - or at least, it should be. If you're the kind of writer who's happy to rip off another author's work and claim it as your own then you're not going to last very long in this business, I'm afraid.
Humans have been speaking and writing stories for thousands of years. So it's no surprise that there's very few stories out there that can be said to be truly 'original'. Every author will pick up bits and pieces from other novels that they've read, or films they've seen, or even music that they like to listen to. Undoubtedly, these ideas are going to seep in their writing somehow or other, and that's okay - that's what inspiration is all about.
Writing isn't about stealing other people's ideas - it's about gathering together ideas you've seen/heard and putting them altogether in your own unique way. Sometimes authors are going to slip up (case point: The Hunger Games Mahogany Incident), but in general, readers aren't going to care if you use a well known phrase or situation ( a man running to the airport to stop his true love from leaving? A villain saying 'there's nothing you can do to stop me'? A chosen one who's destined to save the world? You know what I'm talking about...), so long as the bulk of your story is your own. There are a million different ways that you can put your ideas together - really, there's no reason why your story should copy anyone else's.
So don't be discouraged if you want to write a story about a girl who moves to a small town, falls in love with a vampire and eventually becomes a vampire herself - yes, it's been done, but the important thing is that you put your own spin on it, and make it your own. Don't let anyone tell you what you can or can't write - just make sure you're not following someone else's story too closely ;).
How about you? Do you think any story can be truly original?