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In biology, immunity is the state of being insusceptible or resistant to a noxious agent or process, especially a pathogen or infectious disease. Immunity may occur naturally or be produced by prior exposure or immunization .
The innate immune system or nonspecific immune system [1] is one of the two main immunity strategies in vertebrates (the other being the adaptive immune system). The innate immune system is an alternate defense strategy and is the dominant immune system response found in plants, fungi, prokaryotes, and invertebrates (see Beyond vertebrates). [2]
Non-specific immunity, or innate immunity, is the immune system with which you were born, made up of phagocytes and barriers. Phagocytosis , derived from the Greek words phagein , meaning to eat, kytos or cell, and “osis” meaning process, was first described by Élie Metchnikoff , who won the Nobel Prize 100 years ago.
Adaptive (or acquired) immunity creates an immunological memory leading to an enhanced response to subsequent encounters with that same pathogen. This process of acquired immunity is the basis of vaccination. Dysfunction of the immune system can cause autoimmune diseases, inflammatory diseases and cancer.
An individual's immunity can be acquired via a natural infection or through artificial means, such as vaccination. [51] When a critical proportion of the population becomes immune, called the herd immunity threshold (HIT) or herd immunity level (HIL), the disease may no longer persist in the population, ceasing to be endemic .
Natural immunity is gained by those organisms whose immune systems succeed in fighting off a previous infection, if the relevant pathogen is one for which immunization is even possible. Natural immunity can have degrees of effectiveness (partial rather than absolute) and may fade over time (within months, years, or decades, depending on the ...
Natural immunity, like immunity provided by vaccines, also wanes over time. That means a person can get reinfected and then spread the virus to others, ...
Immunology is a branch of biology and medicine [1] that covers the study of immune systems [2] in all organisms.. Immunology charts, measures, and contextualizes the physiological functioning of the immune system in states of both health and diseases; malfunctions of the immune system in immunological disorders (such as autoimmune diseases, hypersensitivities, [3] immune deficiency, [4] and ...