
I'd still not give him a third vaccination, whatever good the vaccines do will be there already from the two (assuming he didn't have the first too young, and then only for those diseases requiring two which is the lepto and Parainfluenza).
If vaccinated after 12 weeks one vaccine will give immunity for the viral diseases with modified live vaccine components.
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."
"The Magic Number
It appears that 12 to 16 weeks would be the magic number where vaccines have a nearly 100% chance of working.
And by working, it means that your puppy should only need that one vaccine – for his entire life.
The results are even more amazing with distemper.
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.
Although two and even three doses of vaccine were the original recommendations made in the AAHA Canine Vaccine Guideline back in 20013, the research shows that a series of puppy shots is completely unnecessary.
Puppies vaccinated once at 12 to 16 weeks of age with a high titer vaccine, according to research done by Dr Schultz, have a virtually 100% chance of being protected.
But aren’t the puppies at risk until 12 weeks of age?
Yes it is. But ironically, there’s even greater risk for puppies given a series of shots.
Not only do these puppies receive more vaccines, meaning they’re more likely to suffer from vaccine-induced chronic disease, there’s a little downside to vaccines your vet doesn’t tell you about …
… they suppress your puppy’s immune system. For ten days.
So if you’re vaccinating your puppy at 8 weeks, not only is it not likely to protect him and he’ll need another at 12 and probably again at 16 weeks, but it suppresses his immune system, meaning he’s MORE AT RISK for infectious disease.
So it’s no wonder why data from the Virbac Disease Watchdog shows that 28% of vaccinated puppies still get parvovirus.
So does the series of puppy shots still make sense to you?"