Vampirism Corruption, When are you a vampire?

[Rylden]

So in an upcoming campaign I'm going to try out this new corruption system. Going over the different manifestations I've noticed none of them actually state you become a vampire at X manifestation. When would you be classified as a vampire in terms of being able to take feats with Vampire as a prerequisite?

Do you just never become a "vampire" until your corruption hits level 3, and you lose your character?

[Rysky]

Pretty much.

The Corruptions weren't made to allow you to play a monster.

If Templates aren't allowed but 3pp is you might want to look into Fire Mountain Games' Line of Vampire feats if you want to play an actual vampire rather than use the Corruption.