The article raises this question: "Are myths about the rejuvenating powers of young blood true?"
The answer, as I discern it from this and other literature: Definitely yes and no.
Not long ago here we posted about some research in Lund, Sweden attempting to rejuvenate blood (of mice) by reprogramming stem cells. Link to that post and the article on rejuvenating blood The broader topic there, of course, is the search for methods of achieving radical life extension.
My point is that the idea of recapturing youth by somehow rejuvenating via young blood is very new-- witness the Swedish research. But it is also very old, as recounted in this article in the Briish AEON, which begins way back in the myths of ancient times and carries through to what's happening now. Oh yes, vampires are covered in it, as well. Here's the link to that AEON article