The information that is available on products being considered and the source and quality of the information. Challenge One thing to keep in mind is that challenge and protection are in a constant state of fluctuation. We like to think that when we vaccinate an animal, they all develop a certain level of protection. However, biological variability affects the level of protection. The same is true with the amount of exposure to a pathogen.
Overwhelming challenge can override the immunity and lead to disease in vaccinated animals.
Timing of Disease Many of the farms we work with will have a consistent times when certain diseases occur. The timing may give some insight into stresses that are occurring in the management of the cattle that can be dealt with and have more of an impact than vaccination. Furthermore, this type of a history is helpful to determine the timing of vaccinations. This is a tool that is often under utilized in veterinary medicine but if we know when a problem is occurring prevaccination schedules that will give maximum immune responses close to the expected trouble time can be very beneficial. Assesing Vaccine Efficacy Vaccine efficacy can be extremely difficult for the practitioners to assess.