From The Great New England Vampire Panic:
Though scholars today still struggle to explain the vampire panics, a key detail unites them: The public hysteria almost invariably occurred in the midst of savage tuberculosis outbreaks….
“People find themselves in dire situations, where there’s no recourse through regular channels,” [Rhode Island folklorist Michael Bell] explains. “The folk system offers an alternative, a choice.” Sometimes, superstitions represent the only hope, he says.