Fundamental Considerations in Developing Vaccination Protocols

Abstract

A tremendous amount of time, effort and expense is placed on vaccination programs in the cattle industry. Recent surveys of vaccination practices in the U.S. suggest that many producers are not effectively vaccinating their animals for optimum immunity. Development of an effective vaccination program requires a thorough understanding of vaccine immunology. Antigen processing and presentation are key mechanisms of an appropriate immune response and affect the type of response that can be expected from different types of vaccines. Modified live vaccines provide effective humoral and cytotoxic immunity that is long lived. Killed vaccines can provide effective humoral immunity when appropriate adjuvants are used. New concepts in antigen presentation and adjuvants will undoubtedly improve the immune response elicited by future killed vaccines. Vaccination programs should adopt a concept of strategic vaccination in order to provide the most effective immunity to the animals prior to stress or exposure. Vaccination programs may be monitored in the field by evaluating specific serological responses. This information can be used to compare vaccines and vaccination programs as well as provide information that can be used to differentiate vaccine responses from recent infection. While vaccines are instrumental in decreasing disease incidence and severity, there are inherent risks. Adverse reactions include systemic responses to endotoxin, anaphylactic and anaphylactoid reactions, vaccine induced disease, and reproductive effects including infertility and abortion. These risks can be minimized by appropriate use of vaccines. Ultimately, we expect vaccines to be efficacious and provide a positive economic return to the producer.