alt Hacker NewsWatts did a whole academic presentation on the science of vampirism in the book's context. It's a fun watch and makes it feel much less random. https://www.youtube.com/watch?v=wEOUaJW05bU
If you want a really shoehorned scifi vampire, there's a David Weber book in which it comes out of fucking nowhere towards the end.
Best explanation for vampires not liking crosses I have ever seen. I always enjoy vampires that are explained scientifically for some reason in fiction, its like some sort of challenge and they usually avoid the whole dislike of crosses, not here, thought it was a decent attempt along with many other ideas in the book, very enjoyable to me.