HERD IMMUNITY
Charles François (2004). HERD IMMUNITY, International Encyclopedia of Systems and Cybernetics, 2(1): 1515.
| Collection | International Encyclopedia of Systems and Cybernetics |
|---|---|
| Year | 2004 |
| Vol. (num.) | 2(1) |
| ID | ◀ 1515 ▶ |
| Object type | Human sciences, Methodology or model |
The resistance to propagation of a contagious process in a composite system when the contagious element is insufficiently numerous.
C. WILLS writes: “If most of a herd is immunised against a disease, that disease can no longer spread easily, and the few unimmunised animals are also protected” (1996, p.41).
In more general terms, avalanches and other percolation effects in composite systems occur only if a critical density threshold of the perturbating elements is crossed.
Herd immunity is related to the degree of diversity of elements or evenness in the defined space.