I always understood that fish that survived KHV were carriers themselves, and could infect other fish.
I think To get rid of KHV totally from a water it has to be drained, the bottom limed and allowed to stand fallow, and can't be restocked for 2 years.
This allowing fish movement from a water that was even suspected of having KHV in the past is just plain stupid, and shows how easy it to transfer disease from water to water. That is infected fish from 10years ago, not just a year or so!
It is not hard to look at past records of KHV outbreaks, probably most of them are on EA website, or even here, (😉😅)