Not Used: Werewolf semiclass

I noticed that there is a werewolf semiclass, someone told me it while I was in game.
I was told the requirement is to be infected with lycanthropy, but what about players who can't due to the fact they are already lycans (wolfblood).
Also vampires normally aren't able to become a werewolf because they are dead, and disease does not effect the undead in the same form as living, so will we be having an army of werepyres too?

Just a thought, limit the werewolf semiclass to non-undead characters, and allow wolfbloods to bypass the 'being bitten' quest.

Wolfbloods are descendants of werewolves, but aren't full-blooded werewolves.

Vampire PCs are only partially-dead. They can still get diseases and suffer from poison...the blood flowing in their veins just happens to be from what they drink, rather than produced by themselves.

Wolfbloods and vampires are able to take on the Werewolf semi-class. They still must be "infected" by being bitten by a real werewolf, just like anybody else, so it's possible.