Vaccination Failures: Is It the Vaccine or the Protocol?

Vaccination remains one of the most effective preventive measures in veterinary medicine; however, vaccine failures continue to occur despite the availability of effective immunization programs. Failure to achieve protective immunity may result from vaccine handling and storage issues, inappropriate vaccination schedules, interference by maternally derived antibodies, host immune status, concurrent illness, pathogen variation, or errors in vaccine administration. Distinguishing true vaccine failure from protocol-related failure requires careful evaluation of patient history, vaccine type, timing, environmental risk factors, and herd or population health status. A systematic understanding of these contributing factors is essential for maintaining effective disease prevention and optimizing vaccination outcomes in companion and food-producing animals.