Christopher Lee as Dracula passed away, R.I.P.
Do you believe in vampire? I do not.
However, there are some people believe that vampires exist in the real world. According to them, vampires are hiding themselves from the society so that they are not discriminated, especially by doctors.
International Business Times: Real-life vampires are shy because they don't want to be stereotyped by doctors
Actually, if a patient introduced himself as a vampire, I would diagnose him as delusional disorder. In that sense, I understand their concern.
There is an academic article discussing the matter. In this study, real vampires were proven to be distrustful of social workers and to be scared being misunderstood.
University of Windsor: Do we Always Practice What we Preach? Real Vampires’ Fears of Coming out of the Coffin to Social Workers and Helping Professionals
According to Atlanta Vampire Alliance, "a vampire is essentially an energy feeder or blood drinker that may display various levels of psychic ability." This definition is not so different from that I imagine from this word. But I think it is natural that bloodsuckers are disliked by ordinary human, unfortunate for them.
In a more generalized view, persons who have an alternative identity tend to experience some suffering in their daily life. It is partially unavoidable, but still not acceptable. A society in which any diversity is welcome is desirable, in the concept of modern liberalism. We have to think how can we help the minorities any time.
By the way, delusional disorder is relatively difficult to diagnose. How can you judge the claim of a woman that her husband is having an affair? It must not occur that CIA is spying you exclusively, but not by 100%. How about alien, ghost, or vampire? Common sense is not always your ally.