prions are a specific sequence, the danger with a prion is that they stack up on each other like building blocks and produce "plaque" structures, there is such a difference that it is about as close to zero as you can get.
what you would get is some false starts, and segment of protien if that at all.
The CDC and other sources argue the vaccine is safe because it doesn't alter your DNA, but I have a vivid imagination and can think of a thousand other ways something might go wrong. Having my DNA altered was never one of my concerns.