This page gives information about how the immune system works and how immunizations for kids provide protection from infectious diseases.
To read more on the diseases immunizations for kids protect against, click here.
To read about the childhood immunization schedule for your country, click here.
A vaccine is an agent that stimulates the body's immune system to provide a response that will mean protection from that disease in future. So whooping cough vaccine leads to immunity from whooping cough.
An immunization refers to the process when the body develops immunity to a vaccine. Sometimes, vaccine and immunization are used interchangeably, so immunizations for kids and vaccines for kids mean the same.
There are many mechanisms the body uses as defence, including :
The immune system is a network of cells and organs that protect against disease. Viruses and bacteria that cause disease have antigens on their surface. Antigens are like markers and the body recognises antigens as foreign and fights them.
The white cells in the blood are one of the main arms in the immune system that fight infections. Some fight the infection by engulfing and ingesting the offending organism, (this is called phagocytosis). Phagocytes that attack the offending organism where they find it are called polymorphs – these usually offer an immediate but a short-lived response.
Other phagocytes called macrophages see the antigen and engulf the cells and then they transport the cells in the lymphatic system to the lymph nodes where they break them down. The lymph nodes are usually enlarged during infections as a result of this white blood cell activity. To read more on large lymph glands, click here.
Other important white cells involved in immunity are the B-lymphocytes and T-lymphocytes. These swing into action after the macrophages have brought the antigen to the lymph nodes, so these cells are not available immediately to fight new infection.
T cells (or T lymphocytes) use chemicals to destroy the cells in your body that are already infected. They also send chemical messages to the B cells to help in their fight against disease. It can take about a week to 10 days for this system to start working for a new antigen, so it is not good as an immediate defence.
B cells (or B lymphocytes) make antibodies. Each antibody is specific for a type of antigen – they join together a bit like a lock and key. If the body has not seen the disease already, it takes time for the antibodies to develop (up to 10 days). Antibodies attach to the antigen and attack the foreign organism both directly and indirectly by alerting other parts of the immune system to the foreign antigen. The B cells also make memory cells which remember that organism so are ready next time to quickly make antibodies.
Immunizations for kids work by making memory B cells. So if you child gets an infection, the body already has experience and can act immediately, rather than waiting for the antibodies to develop from new (which can take up to 10 days by which time the bug will have affected the body). The vaccines used in childhood immunizations mimic the diseases they protect against and the body reacts by making antibodies and memory cells. If your child then gets the infections, the memory cells recognize the antigen and immediately make antibodies which get rid of the organism before it can cause infection – thereby providing protection against that disease. Even if you do get the disease after immunization, it will only be a mild form of the disease. So immunizations for kids are great at boosting natural immunity and protecting your child.
Immunizations for kids usually don't make them sick because the part of the bacteria or virus that makes people ill has been removed, killed or changed in some way.
There are various types of vaccines used in immunizations, including:
Active immunity is what you get when you a disease or you have an immunization – so the body makes memory cells for that disease. This usually lasts forever, but may wane slightly which is why booster doses of immunizations are sometimes required. This is the basis for immunization for kids
Passive immunity is when you get antibodies to a disease from someone else – this happens when a baby receives antibodies from his mother via the placenta. These antibodies are present only transiently so only provide short term protection. Similar passive immunity is achieved with immunoglobulin treatment.
Immunization for kids provides active immunity.
Last reviewed 22 May 2011
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