This is what Dr. Ronald Schultz had to say in his 2007 presentation to the AKC Canine Health Foundation entitled,What Everyone Needs to Know About Canine Vaccines and Vaccination Programs http://www.puliclub.org/CHF/AKC2007C...20Vaccines.htm
"An antibody titer no matter how low shows the animal has immunologic memory since memory effector B cells must be present to produce that antibody. Some dogs without antibody are protected from disease because they have T cell memory, that will provide cell mediated immunity (CMI). CMI will not protect from reinfection, but it will prevent disease."
"My own dogs, those of my children and grandchildren are vaccinated with MLV CDV, CPV-2, CPI, andCAV-2 vaccines once as puppies after the age of 12 weeks. An antibody titer is performedtwo or more weeks later and if found positive our dogs are never again vaccinated. "
The vaccines in the quote above are CDV (distemper), CPV-2 (parvovirus), CPI (canine parainfluenza), and CAV-2 (hepatitis), and Dr. Ronald Schultz is the Chair of the Department of Pathobiological Sciences at the University of Wisconsin School of Veterinary Medicine. His challenge and serological studies on canine vaccines form a large part of the scientific data base upon which the 2003 and 2006 American Animal Hospital Association's Canine Vaccine Guidelines are based, as well as the 2007 World Small Animal Veterinary Association's Vaccine Guidelines.
Duration of Immunity to Canine Vaccines: What We Know and Don't Know
, Dr. Ronald Schultz http://www.cedarbayvet.com/duration_of_immunity.htm