True. Puppies receive maternal antibodies through nursing. That is why they receive so many boosters - we are not sure when exactly those maternal antibodies become ineffective, and it varies with every puppy, so the puppy shots are done in a series so that our bases are covered. When you vaccinate a puppy that still has those maternal antibodies in effect, they kill the vaccine as if the body was actually being infected by the virus. Therefore, the vaccine was useless.
That is part of why I refused to do the last round of puppy shots with Gusto (the vet wanted to do at least 3, they preferred 4). I stopped after 2, and then did the 1 year booster. He'd been taken away from his mother at something like 4 weeks; I wasn't worried at 15 weeks that there were still maternal antibodies in there.
One vaccination would be sufficient to keep a puppy protected. Why then do puppies need to be vaccinated every two to four week until they reach the age of 16 weeks?
Colostrum, a mother's first milk contains antibodies that provide the puppies with passive immunity. The immune systems of puppies are not fully mature but they are protected by maternal antibodies against common diseases. These maternal antibodies will eventually weaken as the puppy gets older. The rate of weakening though is different between dogs. If the puppy still has high level of antibodies in its bloodstream the effectiveness of the vaccine will be blocked. Puppies have to be vaccinated several times because it is very hard to predict the amount of maternal antibodies they still have.
This is why we prefer vaccines at 8 weeks, with boosters at weeks 12 and 16. Then we booster at a year and then every three years. Rabies is given at 16 weeks, booster at a year and then also every 3 years.
My dogs also get bordetella because they come to work with me all the time and board occasionally and lepto because they both enjoy drinking and splashing in the muckiest water they can find and we've had 3 positive cases in the 3 years I've worked at this particular clinic. Lepto is yearly.
I don't think the weaning has anything to do with this. Colostrum is only secreted for the first 24 hours or so (I think it may be 48 in dogs, but you ideally want it within the first 8) from the mother and there's a time limit on when the puppy can absorb it too. I can't remember if it's in dogs or humans that IgA provides an enteric role after the initial absorption (of IgG/IgM) but it's one of those two (I think it's humans). Absorption falls off pretty rapidly so if the dog is still nursing, it wouldn't really have any affect.
There'd really only be a correlation between the age of when a dog would typically still be suckling vs when you vaccinate, and that's already been talked about with maternal antibodies.
Well and it isn't so much a matter of "doing the first one over." The number of boosters a puppy gets or whether an individual booster is the "first" one or not or when it weaned aren't very relevant to long-term immunity, it's the timing/age of the puppy of the last 1-2 boosters that matters most.