User blog comment:VampiresAndWerewolfsareAwesomeAsHell23/Vampire Transformation/@comment-7600752-20140619063607

I don't think the venom has to 'saturate' every single cell in the body to become vampire. The reason I believe this is because it's stated in both the book and movies that the reason newborns are so strong is because they still have human blood within their system. It takes about a year for the human flesh to become so saturated with venom that their strength begins to weaken until they are completely vampire and end up a bit weaker than newer vampires.