Ideally, we should all be familiar with the concepts of passive and clostral immunity. In the womb through the placenta, and in the first days of feeding with colostrum, the puppy receives antibodies from his mother. Thanks to these maternal antibodies, the puppy is protected from all infections for the first 10-12 weeks of his life.
The decrease in the level of protective maternal antibodies is gradual, and as the number of maternal antibodies decreases, as well as under the influence of the environment (diverse, breeder-introduced, nutrition, development and growth of the nervous system, muscle mass, and metabolism), the puppy's body begins to learn to work as an adult. As long as the level of maternal antibodies remains high (or sufficient), they are excellent at fighting external viruses without any help.
WARNING: Maternal antibodies protect puppies from more than just pathogens. Maternal antibodies (passive immunity) will also fight as hard against the external strain of the virus - that is, the vaccine!
Therefore, a puppy who has been vaccinated before the mother's antibodies have finished his work will first fall into the most dangerous risk group and will catch an infection rather than a single-age, non-vaccinated (by nature) puppy. Early vaccination (until the end of maternal immunity) is the most common cause of the uselessness of vaccination, which breeders who "fell" on the supposedly "new" advertised way to "vaccinate" puppies in infancy. Some of them manage to vaccinate puppies completely. It's just dangerous for a puppy's life, as the owner and breeder believe that the puppy is protected, but in fact, it's not just that, but quite the opposite!
There's also the notion of a "window of vulnerability" in veterinary medicine. It's a time in puppy's life when his puppy's blood levels of antibodies are still high enough to deal with the vaccine virus (i.e. just "kill" the vaccine, while the breeder is sure he's vaccinated and protected!), but not enough to fight the real infection.
That is, up to two months from the date of birth, the puppy retains 100% of the passive (maternal) immunity that his mother gave him, thanks to the clever nature of the puppy and in spite of the idiotic veterinary "innovations".
Any vaccine given to a puppy under eight weeks of age will fight against his puppy's maternal active antibodies (maternal immune system). And maternal immunity, protecting her child, will also be fiercely fighting the vaccine. As a result, both of them (passive immunity and artificial vaccine) will kill each other and your puppy will remain naked and unprotected.
However, you'll still have a stamp from a puppy's "Nobivak-Pappie" stamp in your veteran's passport...
And only 2.5-3 months, when the mother's immune system's defenses are coming to an end, puppies should start getting vaccinated. I recommend starting vaccination for puppies from two months and one week after birth.
Believe it or not, I've been doing this for years. Owners of my puppies do the same.
For those who want to have a puppy vaccinated before 2 months of age, I usually suggest contacting other breeders.
I'm not going to argue with anybody about this because my more than 20 years of breeder experience speaks for itself. In my practice there were no puppies who fell ill after vaccination, there was no death of puppies and no so-called post-vaccination reactions, but in fact - just a reaction of a small organism and its weak immune system to the "war" of the two statuses.
I strongly recommend that all future owners of my puppies take their puppies home from a month and a half to two months and vaccinate them on their own, not because I'm too lazy to vaccinate my puppy, but because I think it's the right thing to do! And none of my like-minded people have ever regretted it.
P.S. Who knows when the last time a dangerous and highly variable virus such as parvovirus enteritis was studied? I know. The answer may surprise you - it turns out to be more than 20 years ago! How many times do you think a dangerous and very insidious virus has changed in twenty years? The evolution of the enteritis virus is striking in its speed, its ability to adapt to the external environment, and it is reminiscent of the human GRIPP virus. From which, as you know, there are no vaccinations!
Isn't that the reason why no newfangled vaccines "hold" enteritis? In fact, the same strain of vaccine "migrates" from vaccine to vaccine without change. Only its name and sometimes the country of origin change.
At the same time, the plague virus (endemic and lazy, little changed virus), thank God, you will not meet almost two decades ago! And any vaccine "holds" a plague of dogs, regardless of its price.