Very, very few. All vampires are bound by the blood-bonds to the sires who created them. This means, effectively, that there's no escaping the Syndicate unless your sire dies. Of course, if THOSE vamps sire new ones, they can create little pockets of vamps with no direct ties to the Syndicate, so Malcolm's organization tries to find other ways to keep unbonded vamps inside the outfit, through bribery or coercion.

There are also some vamps who go feral, driven insane by abusive feeding habits and the resulting psychic damage, so these vamps are effectively outside the Syndicate because they have ceased to be useful tools. These vamps are usually hunted down quickly by the Lothanasi - or the Syndicate itself, if they're REALLY acting outrageously.