DOI: 10.36347/sjmcr.2020.v08i04.026

Pages: 508-509

Herd immunity is a form of indirect protection against an infectious disease, and occurs when a large proportion of the community acquires immunity to a particular enemy, either from pre-infection or vaccination, which provides protection to individuals who are not immune to the disease [1]. It is a type of immunity that occurs when a vaccination given to a large part of the population (or herd) provides a measure of protection to individuals who are not immune. The theory of herd immunity suggests that in the case of individual-transmitted infectious diseases, chains of infection are likely to be blocked when large numbers of the population are immune to diseases [2]. Herd immunity was first used in 1923. It was recognized as a natural phenomenon in the 1930s, when it was observed that after a large number of children developed measles immunity, the number of new infections decreased temporarily, especially among children at risk. Mass insemination to cause herd immunity has been common ever since, and has proven successful in preventing 3the spread of many infectious diseases. Opposition to vaccination challenged herd immunity, allowing preventable diseases to continue to occur or re-emerge in communities with inadequate vaccination rates [3]. If a large proportion of the population is immune to a particular disease, it helps these people not transmit the disease, so chains of infection are likely to stop, stopping or slowing the spread of the disease. The higher the proportion of individuals who are immune in society, the less likely they are to mix with people who are carriers of the disease, which helps protect them from infection [4]. The human body fights infectious diseases through the immune system when the immune system is exposed to a new enemy - a virus - it deals with it, and if the person lives and recovers, the immune system develops a memory of this invader, so that if exposed to the virus in the future he can fight it easily [5].