What is herd immunity?

Herd immunity (herd immunity, group immunity), is the resistance of a population or group of livestock to an infection.

A high level of herd immunity indicates a high percentage of animals in the population that are resistant to infection. This is because the likelihood of a disease epidemic depends not only on the number of resistant individuals in the population, but also on the frequency of contact between individuals in the population. If 70-80% of the animals in a population are resistant, a large outbreak epidemic will not occur.

As for biological populations, there are two meanings:

①Population genetics refers to the genetic composition of the population, i.e., the frequency of genes and genotypes in this population. Such as pure line varieties of the population is homogeneous, individuals are pure; and open pollinated population varieties of the population is heterogeneous, individuals are heterozygous. The study of population genetic composition in crop breeding helps in decision making in breeding programs.

②Crop cultivation on the composition of the individual groups of crops planted on the same field. This individual group may be composed of several crops mixed, interseeding or single species, the study of individual groups of individuals in the space occupied by the individual and its expression of the composition of the state and the dynamic coordination of the relationship between the individuals, to help guide the cultivation of high-yield crops.

References:

Population Immunization_Baidu Encyclopedia