How do vaccines work?
Vaccines work by stimulating the body's immune system to produce antibodies to a particular microorganism such as a virus, bacteria, or other infectious organism. The animal's immune system is then primed, or prepared to react to a future infection with that microorganism.
"This reaction will either prevent infection or lessen the severity of infection and promote rapid recovery."
This reaction will either prevent infection or lessen the severity of infection and promote rapid recovery. In other words, vaccination mimics or simulates the protection (immunity) that a pet has once it has recovered from natural infection with a particular infectious agent.
The immune system is complex, involving interaction of various cells and tissues in an animal. The main cells involved in an immune reaction are the white blood cells and the main tissues are the lymphoid tissues such as the lymph nodes.
One of the most important functions of the immune system is the production of specific protein molecules called antibodies. A specific microorganism, such as Feline Panleukopenia Virus, has components called antigens. When a foreign antigen is introduced into the body, the immune system will produce an antibody that specifically binds and neutralizes that specific antigen and no other. The body produces several different types of antibodies.
Other white blood cells such as lymphocytes are able to identify and kill cells that have become infected by the microorganism. This activity of lymphocytes and other immune system cells is called cell-mediated immunity.
After vaccination, just as after recovery from natural infection, the body 'remembers' the specific antigens so that when they are encountered again it can mount a rapid and strong immune response, preventing the cat from developing the disease. The duration of this response varies with the disease, the type of vaccine and other variables. The likely duration will determine the recommended revaccination date.
"...most vaccines work by preventing your pet from becoming ill during a subsequent exposure to specific disease-causing organisms..."
It is important to realize that most vaccines work by preventing your pet from becoming ill during a subsequent exposure to specific disease-causing organisms, but vaccination may not prevent the pet from becoming infected.