Shouldn't vampires be immune to the drugs and traps?

I would think maybe the ancient temple people were before vampires existed and may not be immune to the ancient powers... possibly anyway. Vamps do have their weaknesses - like light especially sunlight - certain curses and reactions to certain chemicals according to various lore - So perhaps things before their time could also affect them. They are only immortal to a degree - as things can harm them and even kill them.