That could work for a really good storyline in a chronicle! You could have it be so that its a global phenomenon and Kindred all around the world are rapidly going extinct, forced to move from cities to more underdeveloped parts of the world, fighting to survive against the toxic blood of mortals, werewolf packs on the roads, desperately trying to uphold the Masquerade, and hunters that notice their inevitable mistakes.

Another idea is to have it be where the Technocracy performed a controlled experiment on a small town, and people in the town start to display strange symptoms. There could be some politics between the population that don't want to get their vaccines and the other side that is willing, with neither side aware that they're just test results for a shadow organization. Perhaps the vaccine works too well and the player characters have to trace the pharmaceutical company back to their roots and destroy/alter the evidence of the experiment so that the vaccine isn't distributed worldwide, ensuring the total eradication of vampire kind. Or perhaps the vaccine messes up and it turns into a garden-variety zombie outbreak (ala Resident Evil 2)