I do not have the answer to your specific question but I don't know if you know of or read information from Dr. Jean Dodds. She is an excellent source of information. She even has protocols set for when/how we should vaccinate our pets. I wrote to her a few times for breed reactions to vaccinations and she is very fast to reply to us (at least a few years ago). Very much dedicated vet (no longer practicing I think - but still very involved in the world of researching, etc re: vaccines.

http://www.itsfortheanimals.com/DODD...-PROTOCOLS.HTM

Vaccinations for my cats and dogs are minimal. If it was not because we travel across Canada/USA with our cats and dogs they would get titers (blood test to tell what is left as immunization). But because of the law, we have to vaccinate every 3 years. It is a shame as we know the vaccine can last much more longer than this. They no longer get any type of shots, but for rabies, because in some States it is mandatory and would be a hassle crossing Canada/USA borders without those certificates. But for the rest of vaccination, I work with titering.

Another excellent source of information is from
Kris L. Christine, Founder, Co-Trustee
THE RABIES CHALLENGE FUND
www.RabiesChallengeFund.org

She works really hard at making sure we stop abusing vaccination in animals.

Good luck in getting the answers your are looking for. But unless mandatory, and even if it was (except for crossing borders), my pets would no longer receive vaccinations once their puppy ones were given. Too many risks involved. But that's me.