Just thought I'd throw this out for discussion
We know that pup takes Maternally Derived Antibodies (MDA) in the colostrum of mum's milk. This results in the antibodies from the mother in the pupís blood interfering with the pup being able to use the vaccine to form immunity against a disease.
The usual routine is to vaccinate at 6 to 8 weeks, and again 2 weeks later in the hope that the pup will then be able to use the vaccine.
Would it not be better if all pups "had" to stay with the breeder until the pup is vaccinated at 14 weeks, to remove the risk of the pup being at risk of catching DHP diseases?
This video is of a young pup vaccinated with DHP, which then caught Parvo and almost died.