Have you ever speculated about the issues Jewish vampires would face? Well, I seem to have too much time on my hands…
The most pressing question is of course what to do about the drinking blood thing. It is well known that Jewish halacha forbids the consumption of animal blood, that’s the reason for going to all of the trouble with kosher slaughtering. But many people may be surprised to learn that this refers only to animal bood, human blood is actually allowed (The Beis Medrash blog: Kashrut for Vampires)! There is an issue of marit ayin (people mistakenly think that one is doing something forbidden because it looks like it to the casual observer), but that can be avoided by making it clear that the vampire is consuming human blood, not animal blood, for example by drinking directly from the neck of a person.
But what about shabat? Can a vampire drink from a person’s blood on shabat? Causing an animal or a person to bleed is a violation of the melacha of shochet (slaughtering), even if the living being in question does not die of the wound.. Even if our vampire were to somehow take advantage of a wound that’s already there, the drawing of blood is forbidden due to the malacha of dosh (squeezing). So an adult vampire will probably need to fast or prepare some blood in advance (while taking care of the marit ayin issue, see above). Similar to the argument that nursing a baby is allowed on shabat even though liquid (milk) is squeezed out, an argument might be made for very young vampires where regular nourishment is vital for their health so that they may be allowed to squeeze blood out of a wound.
What about prayer times and praying with a minyan (for male vampires, females can simply pray on their own whenever they please)? Vampires are nocturnal and don’t approve of (or maybe even die when exposed to) direct sunlight. So I think they would form their own minyanim instead of going to regular ones. They would put shacharit (morning prayer) as early as possible, then go sleep during the day and rise again for a very late mincha (afternoon prayer). As far as I could find out, most parts of shacharit (morning prayer) may be said starting from Olot HaShachar (72 minutes before sunrise) or MeSheyakir (some amount of minutes before sunrise that I couldn’t figure out). I guess anything before sunrise would still be dark enough for a vampire. They would need to pray fast, though, to be finished until sunrise. According to some opinions mincha (afternoon prayer) may be said "until nighttime", so I guess if you squeeze it in just before nightfall, it would be suitably dark (Halachipedia: When Is the Earliest and Latest Time to Pray?). Aravit (evening prayer) is not a problem anyway, because it has to be said after the new day starts, which is usually at nightfall. Shabat and holidays start one hour earlier, that might be a problem, but I am not sure how to apply the earliest/latest times for mincha and aravit there. Anyway, thick curtains and underground passages may solve the whole issue even if the sun still needs to be up for the prayers.
An important question from the victim’s side is whether others can protect themselves against Jewish vampires by using holy symbols. The question here is really whether any holy symbol is effective against any vampire or whether only the holy symbols of the vampire’s own (former) religion work. Literature seems to disagree on this point. In any case, what Jewish symbols could possibly be used? Today, the star of David would be an obvious choice, but this hasn’t been a uniquely Jewish symbol until the 19th century and vampires are quite old-fashioned. So maybe a menora? Or an item with religious use such as tallit, tefilin, lulav, shofar or even a chanukia? There seems to be little available data on this point, but one thing is for sure, only very few of the victims are going to have any Jewish religious item at hand or will even know what to look for. So it will be really hard to further investigate this point.
And last but not least, the final question: Garlic. It is inconceivable that Jewish vampires would have a problem with garlic, so they should have at least one advantage about Christian vampires!
To sum up, a Jewish vampire would have some logistics to work out, mainly related to food on shabat and prayer times – but isn’t that the same for all Jews?