
The science suggests that if the vaccine works it works very quickly, or the core diseases with modified live vaccines.
Apart from Lepto and Parainfluenza, the first jab may well have taken if maternal antibodies had waned enough, the reason fro two is that if the first doesn't work the second one will if given late enough for the maternal antibodies to have reduced far enough.
http://www.dogsnaturallymagazine.com/taking-the-risk-out-of-puppy-shots/"The vaccine manufacturer Pfizer performed a field study in 1996. Researchers Hoare, DeBouck and Wiseman assessed vaccinated puppies and split them into two groups.
Group A received a single vaccination at 12 weeks
Group B received a first vaccine between 8 to 10 weeks and a second shot at 12 weeks
When titers were measured (titers are a way to measure a dog’s level of immunity), 100% of the puppies vaccinated once at 12 weeks were protected.
But only 94% of the puppies in Group B were protected …
… despite receiving two vaccines as opposed to one.
It would appear that the first vaccine reduced the effectiveness the the second vaccine.......................
Vanguard also tested the response to parvovirus in their combination vaccine.
They vaccinated puppies at 6 weeks, 9 weeks and 12 weeks of age and then measured their response to the vaccine by measuring their titers to parvovirus.
At 6 weeks, only 52% of the puppies were protected, meaning that half of the puppies vaccinated at 6 weeks of age would get all of the risk from the vaccine and none of the benefit because their maternal antibodies inactivated the vaccine. At 9 weeks, 88% of the puppies showed a response to the vaccine. At 12 weeks, 100% of the puppies were protected................................................
Dr Schultz designed a study to mimic an animal shelter environment. He gave unvaccinated, 12 week old puppies just one dose of distemper vaccine … just four hours before the puppies were placed in a room with distemper-infected dogs. Yikes!
But that one vaccine protected every one of those puppies."