Well, viruses aren’t alive either. I would say they are very similar to Prions in the aspect, that it is just a rogue biological building block, able to get itself reproduced, to the dismay of the body.

Also there is no reason, why you couldn’t develop vaccines against Prions. It could be even simpler, because they have to be shaped very specifically to cause the harm they do, and it should be easy to break that specific shape with something attaching to it.