I am not a vet or anything like that but a while ago i had the same questions you have...i now have decided NOT to vaccinate Mojo yearly...now let me explain...
Vaccines are nothing more that the actual virus that causes the disease (ex. parvo shots contain parvovirus in it), now the vaccine can either contain killed virus or modified-live type.
Now, by giving the vaccine all we are doing is force the animal's imune system to creat a response and fight the disease causing virus (that is why sick dogs should never be vaccinated, the shot could simply make the dog sick when a healthy dog will have the strenght to fight it off and win against the disease).
The questions with vaccinations was simply that why we should vaccinate yearly if the dog can stay imune to the disease for way longer than that? The way i see is if i am yearly giving my dog something that will not change his protection to disease in any why...i really do not see the point!
Many studies were made regarding that and it was shown that in some case the imunity aquired through puppy shots last a lifetime...
Now over 30 states already accept the 3 year rabies shot, which, as far as i know, is the only vaccine required by the government.
My personal choice is to give my dog his rabies every 3 yrs, as required, and every 3 yrs get a titer test to check his imunity...As per bordatela (aka kennel cough shot), Mojo had it as a puppy as well but i can say that he will never get it again.
I believe dogs need vaccines but i also believe that over vaccinations are bad and can bring serious reactions to some pets...but that's imo, i added some links bellow in case you want to read more
http://www.canine-epilepsy-guardian-...titer_test.htm http://www.doglogic.com/vaccination.htm http://www.vetinfo.com/dogvacc.html#...n%20rethinking