okay, one more thing:

is Saul the first Ground-Zero breather to be bitten? He's the test, in my book, to see if there is a true immunity. Randy bit him, but it may not necessarily mean Saul turns. Tanya's Keratin levels were normal at the time she could endure the gas in the last episode. So to me, that's a natural response and not her body adapting.

but what we do know, is that Saul is a tought SOB. he will go down swinging.