We would like the vaccine to produce lifetime immunity but most vaccines are protective for a year or less. Also, vaccines should not produce side effects. The cost of vaccines should be less than the cost of the disease. However, cost effectiveness must be measured in the long-term to be useful. There are two general philosophies to guide selection.
Some producers believe vaccines are an investment.
They expect the cost of the disease will be greater than the vaccine use. Others use vaccines for insurance with little information as to the cost of disease. Vaccines are used in an attempt to reduce the chance of catastrophic losses occurring even though the likelihood of this happening is quite small. Vaccines should be used as a management tool that is part of an overall program to produce a quality product. Remember that there will always be more diseases than vaccines.