To the above comments, there are various types of vampires prevailing. As mentioned, the author talked about psychic vampire, which is different from the pure blood sucker. Kuntilanak is a variation, so is Pocong, Toyol and others. Some creatures requires blood to survive, some do not. Some creatures do not require blood, but when given, it strengthen them. Some requires other things in order to cultivate a more powerful form, in the story’s case, the vampire requires mainly Qi.

For your information, Twilight movie may contain sublimal messages about vampires, it may seems exaggerating, but there are sublimal messages to it. The term vampire is vague, and does not accurately describe the types of blood suckers or partial blood suckers. That’s the reason why there are so many types of ghosts in the Taoist and Malay lists, because the term vampire cannot accurately depicts the various types of creatures encountered by people.

The vampire that was mentioned to be ‘dead already’ belongs to the more etheral realm, and their requirement for survival is different from ‘living’ vampire that live amongst human. Human have various multiple layers of souls, each requires slightly different kind of energy-nourishment. So it depends on the vibrations of their bodily cells’ composition.

As per author’s story, it is unsure of the conclusion, however, we are given some hint of the life of a psychic vampire. This is just a tip of an iceberg’s of my knowledge to this matter. I will try to answer if there is any query.