Active immunity - vaccinations
A vaccination is the injection of dead or modified microorganismMicroscopic (too small to see) organisms, such as bacteria and viruses.
The body鈥檚 lymphocytesWhite blood cells which attack pathogens by producing antibodies. produce antibodyA chemical produced by a lymphocyte in response to an antigen. in response to the antigenA marker on a microorganism that causes the body to produce antibodies. present in the vaccineA substance that stimulates the body to produce antibodies to provide immunity against a disease..
Memory lymphocytes will also be produced 鈥 this is the primary response.
If this microorganism is encountered after the vaccine, the memory lymphocytes will produce large numbers of the antibody very quickly.
The individual does not get sick 鈥 this is the secondary response.
Sometimes a booster vaccination is needed to maintain the high levels of antibodies needed to provide immunity.