Vaccination principles


The use of vaccines has been proven to be highly efficacious and beneficial to the health of veterinary patients as well as the general public. Historically, vaccination has had a dramatic effect upon decreasing the incidence of infectious disease in the animal population. Appropriate decisions concerning individual vaccine selection and vaccination program choices are best made under veterinarian-client-patient relationships. Best practices suggest veterinarians should create a core vaccine program intended for use in the majority of animals in their practice area as well as a non-core vaccine program, intended for special circumstances based on individual patient assessment. Vaccine programs should follow all governmental regulations. The AVMA advocates a medically based approach to vaccination based on the preventive health needs of the individual patient.

Vaccines are used to induce an acquired immune response to a disease agent beyond what might be present as a part of the innate immune response. The efficacy and duration of immunity (DOI) of an individual vaccine is highly dependent upon the type of vaccine (e.g., modified live, killed, recombinant/vectored), the individual patient’s health, age, genetics, and exposure history. While vaccine safety is tested by vaccine companies prior to licensing for general use, individual instances of adverse reactions can and do occur. This is generally a small percentage of the vaccinated population, and the benefits of vaccination have been shown to far outweigh the risks.

Label indications and recommendations should be followed. However, veterinarians may legally exercise discretionary judgment in some instances if medically justified and when in compliance with all governmental restrictions that may apply. All manufacturers’ information concerning vaccine handling guidelines should be followed to help ensure vaccine efficacy, safety, and potency. Failure to administer a vaccine in the method deemed appropriate by the manufacturer (e.g. allowable concurrent treatments, route of administration, full dose) may result in suboptimal protection and/or adversely alter the established safety profile of the product. All manufacturer cautionary warnings on vaccines should be followed. Veterinarians should recognize that failure to use vaccines according to manufacturer-labeled directions may result in potential liability to the veterinarian in the case of an adverse event or lack of efficacy. The induction of a protective immune response may require a primary immunization followed by a booster vaccination. In young animals where animals where maternally derived antibodies are still present, multiple vaccines may be required over a period of several months. Immunity is dependent on multiple factors, including but not limited to: medical history, vaccine type, method of administration, age, and species being vaccinated.

Antibody titers or other immunological measurements to determine if booster vaccination is warranted should not be used if standardized tests and protective levels of immunity have not been defined for the disease.

Vaccination programs should be designed to maintain the health of the animals and protect public health while minimizing adverse effects. Veterinarians should evaluate the risk/benefit ratio before vaccination of a patient, taking into account the general health of the patient, the vaccine antigen/adjuvant combination, routes of administration, herd/flock immunity and public health concerns, and concurrent drug or chemical use. Patient disease susceptibility, immune status, and duration of immunity for the vaccine of interest should be balanced when considering the timing of re-vaccination.

All adverse events should be reported to the manufacturer and the United States Department of Agriculture (USDA) to help ensure the continued safety and efficacy of veterinary vaccines.

In developing a vaccine program there are multiple sources of information available from species and specialty groups as well as through the manufacturers’ package inserts and government agencies, in particular the USDA’s Center for Veterinary Biologics. The AVMA continues to advocate for the increased availability of animal vaccines that are safe, efficacious, scientifically-based, and clinically practical, to provide practitioners with a basis for developing optimal vaccination programs. The AVMA encourages the USDA APHIS Center for Veterinary Biologics to ensure the scientific basis of vaccine label revaccination interval recommendations.