In many good restaurants, you get an “amuse bouche” when you sit down to light up your taste buds. The introduction of Sovaldi was an “amuse bouche”, the main course is Sovaldi plus Ledipasvir. Or to forget analogies and get down to the nitty gritty, as long as Sovaldi requires interferon and ribavirin, many will wait, for while not as bad as telaprevir, interferon and ribavirin alone or in combination can be quite nasty.