Female hybrids do not have venom in there system this is proven when Nessie repeadily bites Jacob.
in breaking dawn and him healing with no problem. the venom cain't be less infectious or less potent
this is shown with Nahuel the Venom is either there or not there. Nahuel's venom as as the same as any full vampy beacse he has it like they do as for females they don't have the venon in thems at all. its unknown though weather its random or by gender. but even still Nessie wouldn't need the venom in her system to be fine eitther way