Answer by Jason Corning: Yes, the Star of David would work against a Jewish vampire, and most probably against a non-Jewish vampire as well, because the power of the symbol comes from the faith of the intended victim. This means that a Jew trying to protect themselves with the Star of David would end up being the most potent defense- rather than a Jew using a cross or a non-Jew brandishing a Star of David. Here are the relevant sources-
Symbols of faith will make a vampire recoil in an instant, so long as the person holding it has enough belief and conviction. Traditionally, crucifixes have been used to repel these deadly beings, however, Stars of David, Wiccan pentacles and other symbols are now also thought to be just as effective. Vampires are so petrified of the potential wrath of higher powers; they steer clear of true believers.
– Top 10 Ways to Repel and Kill Vampires, Halloween Alliance
The BBC Television series Being Human (which premiered in 2008 in England and was adapted for North America in 2011) has rules around the Star of David. The Jewish symbol can repel a vampire attack, although with the caveats that the bearer must not feel any affection for the vampire or be outnumbered by them, else its effectiveness is diminished; the oldest vampires are also immune to religious relics. And in the young adult urban fantasy book series The Mortal Instruments by Cassandra Clare, vampires are vulnerable to religious symbols from whatever faith they were as humans.
– How to Kill a Vampire: Crucifixes, Holy Water and Other Sacred Objects, by Kerry Clare, 49th Shelf
In The Uncanny X-Men #159, it is Kitty Pryde's faith in Judaism that allows her symbol (the Star of David on her necklace) to repel Dracula. It is worth noting that in the critically acclaimed DC Comics graphic novel Batman/Houdini: The Devil's Workshop (pub. 2003, an Eisner Award nominee), Houdini also repelled a vampire with a Star of David necklace.
– The Religious Affiliation of Comic Book Character Kitty Pryde Shadowcat of the X-Men and Excalibur, Adherents.com
Jewish vampires also will not be prone to attack anyone wearing a strand of pork rinds around their neck at night. Another religious symbol that is said to be powerful against Jewish vampires is the Star of David.
– Destroying Vampires Around the Globe, Vampires.com