Adapted from the National Institute Allergy & Infectious Disease, National Institutes for Health

Artificial and Natural Immunity

We become immune to germs through natural and artifical means. Before birth, we received natural immunity from our mothers. Once we are exposed to a germ, we get natural immunity from special cells in our immune systems programmed to fight off that pathogen if it invades our bodies again. Artificial immunity can come from vaccines.

Artificial Immunity
Based on the body's natural immune response, immunization with vaccines is a process designed by scientists to create an artificial type of immunity.

• Immunization is a safe way to get protection from germs.
• Some vaccines contain microbes or parts of microbes that have been weakened or killed. If you get this type of vaccine, those microbes (or their parts) will start your body's immune response which will spur the development of new antibodies and white blood cells – just enough to demolish the foreign invader but not make you sick.  Pretty cool discovery by a fellow named Jenner!

To Learn All About Vaccines (immunization),  go to A Parent's Guide to Kids' Vaccines

Natural Immunity
People can become immune, or develop immunity, to a microbe in several ways. The first time T cells and B cells in a person's immune system meet up with an antigen, such as a virus or bacterium, they prepare the immune system to destroy the antigen. Because the immune system often can remember its enemies, those cells become active if they meet that particular antigen again. This is called naturally acquired immunity.

Another example of naturally acquired immunity occurs when a pregnant woman passes antibodies to her unborn baby. Babies are born with weak immune responses, but they are protected from some diseases for their first few months of life by antibodies received from their mothers before birth. Babies who are nursed also receive antibodies from breast milk that help protect their digestive tracts.