I view the concept of an "Enchantment Vaccine" to be a bit off-flavor here... Even if it were ever deemed legal, I see most players house-ruling that it's illegal, bad-form, and taking advantage of a potenitial loop-hole that diminishes the thematic beauty of the game.
The cleanest way to view and interpret the multiple enchantment reveal rule would be that
the first revealed (reveal costs paid) enchantment remains. Any same-named unrevealed enchantments on the same creature are immediately discarded. And no player can KNOWINGLY cast a same-named enchantment on a creature that already has one on it, revealed or unrevealed... So you can't cast 2 Bear Strengths on your own creature.
So to clarify the previous example:
1) Wizard casts Poison Blood on himself (unrevealed)
2) Warlock casts Poison Blood on Wizard and chooses to reveal it, paying all costs.
3) Wizard must now reveal his own Poison Blood enchantment, discarding it immediately, given that his mage already has a Poison Blood enchantment revealed on himself.
If the Warlock chose to not reveal his curse right away, and the Wizard reveals his Poison Blood first, it is immediately discarded without effect if he doesn't pay the reveal costs, allowing the Warlock's unrevealed Poison Blood to remain and be revealed and paid for at a later time.
This ruling would seem to be the cleanest and thematically-realistic, without worry of players taking advantage of a strange wording loop-hole. "I'm playing against a Warlock? Oh, I better cast my Ghoul Rot Vaccine on myself right away...." (sigh...)