Vaccination (or immunization ) is a means by which it is possible to prevent a serious disease through a previous exposure to the suitably treated infectious agent - so as to render it harmless - or to a series of components thereof. In other words, this practice provides the immune system with the opportunity to gain the experience necessary to evoke a protective response against a given pathogenic microorganism, with minimal risks to the health and life of the individual.
Once injected, the vaccine is intercepted by the immune system and determines an immunological memory . If the vaccinated person subsequently comes into contact with the pathogen, the defense cells recognize it, neutralize it and avoid infection or disease. The vaccination, therefore, teaches the immune system to defend itself against an infectious microorganism that it has never seen before, without suffering the damage.
