The basis of any vaccination program is to provide long lasting protection prior to exposure to a disease. Disease challenges can happen throughout the life of an animal. Vaccines rely on the animals own immune system to provide that protection. They do this by stimulating the immune system to produce an antibody response to a specific “foreign invader” such as a bacteria, virus or protein. Most livestock vaccines on the market in Australia stimulate the immune system by introducing a killed or inactivated version of the “foreign invader” to the animal’s immune system. The animals immune system then swings into action and produces protective cells and proteins – including antibodies – that target the specific “foreign invader”.
By using a killed or inactivated version of the foreign invader, vaccines produce a strong immunity to that disease without the animal actually contracting the disease and suffering associated production losses.
To provide long-term protection, most vaccines require two shots. The first shot, or priming dose, stimulates the immune system to recognise the particular bacteria, virus or protein contained in the vaccine. As a result, the animal’s immune system produces antibodies and memory cells against that specific “invader”. This first dose does not give sustained protection^. When you give the second dose, the booster dose, the memory cells produced in response to the first vaccination swing into action, producing antibodies on a far greater scale and in a short period of time. The response to the second vaccination gives the animal protection for up to 12 months*.
To maintain a protective level of antibodies in the animal year on year, annual boosters are essential. The annual booster shot has a similar effect on the immune system as the ‘second dose’, that is, massive amounts of antibodies are produced by the immune system, giving long-term protection.