Interference by maternal antibodies is regarded as a major cause of vaccination failure in puppies. Attempts to overcome this problem have been based on administration of multiple vaccinations. Unfortunately, the old vaccination schedule started too early & the mother's antibodies, that pups get through the milk, interfere with the vaccine. So, they were not immunized. Then subsequent vaccinations too close together only suppressed the immune system & weaken it.

The vaccinations should be given later & less of them given.  Enough to stimulate the immune system & not bombard it at such a young age.

The new vaccine schedule starts at Distemper & Parvo @ 8 weeks when the puppies are weaning or best if off Dam completely.

Again at 12 & 16 weeks. Repeat Distemper, Parvo, Rabies at 1 year of age. Then it is felt by the Vets schools that every 3 years is sufficient for the rest of the dogs life.

Generally, after 7 years of age, dogs really don’t need "Boosters" but most Laws require dogs must have current rabies vaccination.