There are many types, brands, and combinations of vaccines available as well as an ample amount of confusion about the correct use of vaccines. Understanding how vaccines work and how best to use them should result in more effective disease control. A protein produce by the animal ' s body in response to contact with disease-causing organisms or vaccination. The protein provides very specific protection against infections caused by that specific organism only. The most common example is colostrum eaten by baby calves near the time of birth.
Passive immunity is short-lived but interferes with the production of active immunity.
A chemical added to a killed vaccine to improve the amount of immunity produced. We expect the vaccine to completely protect the animal from that disease. This is an unrealistic expectation. Proper use of the vaccine should limit the frequency and severity of the disease . We would like the vaccine to produce lifetime immunity but most vaccines used today are protective for a year or less .