@beardalaxy @greenzeta TL;DR - Depends on the vampire lore, but probably nothing happens.

• Earliest folklore vampires won't be affected, since they're already undead and are basically blood-sucking zombies that only come out at night.
• Most modern western vampires like from Vampire the Masquerade, Van Helsing, Dracula, etc... will not be affected, as they are servants of Satan, or children of Cain.
• Anime vampires are creatures of immense power, from Vampire Hunter D, Hellsing, Castlevania, etc... all would shrug it off like it's nothing, insulted at the very notion that a lowly zombie can be a threat to them.
• Sci-fi or alternative vampires are really the only ones that are susceptible, like in Blade, or maybe Legacy of Kain (though that's debatable, as they are undead, animated via soul magic, but also mutate, it's unclear).