My understanding about the vaccines is that they will not prevent the disease from coming into your herd; that's for sure. There will still be clinical signs. I believe that the mortality will be very close to the same. The only thing it will reduce is the amount of shedding. Maybe Greg from Maple Leaf will have a better idea of this vaccine, which is not commercially used yet.
On June 15th, 2017. See this statement in context.