Plague City (2017)

from the introduction:
From time to time, some people will renounce their faith or commit suicide (without consequence). However, in rare instances, either of these sins is enough to cause the offender to become an undead vampire after they die. In this particular side-plot, the offender did both...

designer's website blurb:
Plague City is a side-plot, intended to occur in the background of a longer campaign. The events will sneak up on the PCs, becoming more relevant as time goes on – until they can no longer avoid its effects. If they are lucky, they can avoid the consequences of a deadly plague. If they’re heroes, they’ll face the undead vampire causing it…

designer's comment:
This is the fourth official release from Stuffer Shack Press, and I have to say that it’s my favorite. Originally, it was intended to be a one-paragraph plot-hook for Truly Terrifying Vampires, but I just kept fleshing it out because it just kept getting cooler. It’s a side-plot, one that takes place in and around an adventure you’re already running. All of the events take place in or near a large city, and it’s easy to swap out NPCs for those whom your player characters may already know.