This is a summary of an article by Dr. Ron Schultz
It has been common practice since the development of canine vaccines in the late 1950’s to administer them annually. The recommendation to vaccinate annually was based on the assumption that immunity would wane in some dogs, thus to ensure immunity in the population, all dogs required revaccination since it was not practical to test each animal for antibody. Little or no research has been done to demonstrate that the practice of annual revaccination has any scientific value in providing greater immunity than would be present if an animal was never revaccinated or was revaccinated at intervals longer than one year.
In 1978 we recommended an ideal vaccination program would be one in which dogs and cats would be revaccinated at one year of age and then every third year thereafter (1). That recommendation was based on a general knowledge of vaccinal immunity, especially the importance of immunologic memory and on duration of protection after natural sub clinical or clinical infections as well as on limited studies we had performed with certain canine and feline vaccines. Since the mid 1970’s we have done a variety of studies with various canine vaccines to demonstrate their duration of immunity. From our studies it is apparent, at least to me, that the duration of immunity for the four most important canine vaccines (core vaccines) that the duration of immunity is considerably longer than one year. Furthermore, we have found that annual revaccination, with the vaccines that provide long term immunity, provides no demonstrable benefit and may increase the risk for adverse reactions.