D&Dtools1

The subject does not rise as undead spawn should she perish from an undead's attack form that normally would turn her into a spawn (such as from ghoul fever).
This spell doesn't prevent the subject from perishing or provide anything other than insurance that the subject's body and spirit cannot be hijacked by an acquisitive undead creature.
The protection applies if the duration is still effect when the subject first dies; the spell need not linger in its effect over the period immediately prior to a spawn's rise.
This spell cannot be cast on the body of a subject already killed by a spawn-creating undead.