When the Great Shift happened, most people swapped bodies with someone within a few feet of them. Over 99% of people swapped with someone within a mile radius. Every now and again, someone swapped bodies with someone a considerable distance away.
Jason, for instance, found himself halfway across the globe in a new body as a result of the Great Shift. While most people were challenged by the fact that they found themselves in a new body, Jason had the added complication of trying to understand what was going on with no one around being able to explain in a language he knew that the same thing was happening to them. He felt lost and confused, and he knew he had nowhere to turn for help.
His only saving grace seemed to be due to the fact that he had swapped into a body located near a major tourist attraction, and he eventually found someone who could speak the same language.