But why sunlight burns vampires? Sunlight is natural element. It has nothing to do with gods.
Or why piercing a vampire's heart would kill it?
Maybe damaging vampire's spine would paralyze it for long time and then it would be easy to kill (burn it to ashes, chop it to pieces).
If vampire bites a creature, why the creature becomes vampire? Does the vampire's fangs exude someking of liquid which prevents blood not to coagulate and if this liquid goes to human's system, he'll die and wake up as a vampire.
There is a blood-sucking bat which exudes liquid which prevents blood not to coagulate. In same time this bat may bear rabies which can infect those animals who are biten by the bat.
Vampires do not have great role in my scenario, but there is just a guy who is interested about vampires. He is studying vampires and has information about them.