US companies that sell rabies vaccines routinely recommend that they be given annually. Obviously, these companies have a financial incentive to recommend that their vaccines be given as frequently as possible.
No human vaccine that I know of requires annual booster shots. The standard recommendation to veterinarians that they receive a single primary course of vaccinations and no boosters at all. It seems inconsistent that the CDC recommends that vets that work with sick animals on a daily basis get a one-time vaccination, but the USDA "recommends" house pets get vaccinations every year. My understanding is that this USDA "recommendation" is based on no scientific evidence whatsoever.
Is there any scientific evidence indicating the effectiveness of vaccines as a function of the frequency of their application?