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In simple terms, herd immunity works through achieving a threshold immunity at the population level that is able to theoretically cut the transmission chain of a given infectious disease, be it obtained through natural infection or vaccination. 1 This may not mean that a given individual is fully protected at all times or situations. It is the threshold immunity that, when high enough, can protect most if not all in a population in a given geographical area for a certain time interval.
Feb 4, 2021 · Through herd immunity, the virus struggles to find susceptible hosts, and the chains of transmission break down, so even those who aren’t immune (for example, people who can’t receive a vaccine for health reasons) are protected. Herd immunity rarely occurs through natural disease spread alone, and it rarely brings an end to an epidemic.
Sep 19, 2020 · The “English herd”—those living in England—had herd immunity to plague, malaria, and typhus because they no longer lived in close association with the requisite vectors. Herd immunity took on fresh prominence in the 1950s and 1960s as new vaccines raised crucial questions for public health policy.
Dec 6, 2023 · Herd immunity, or community immunity, is when a large part of the population of an area is immune to a specific disease. If enough people are resistant to the cause of a disease, such as a virus ...
Dec 17, 2020 · For herd immunity we care about VE S and VE I. If a person doesn’t get infected, they can’t transmit, so VE S contributes to x. If they get infected but are less infectious to others, that will contribute to herd immunity, so VE I contributes to x. In fact, the relationship is this: x = 1 – (1 – VE S)(1 – VE I).
Despite the success of select vaccination programs, societal and biological factors (Figure 1), including the inability of population groups to generate protective immunity in response to vaccination is a challenge for achieving herd immunity. The unvaccinated, including the very young, aged, and those who are immunocompromised due to infection, congenital conditions or medical history, must be protected by passive immunity.
level signature of herd immunity , andwe detail this, and alsodiscussother population level outcomes might emerge from individual level immunity. From individual immunity to herd immunity Because of the feedbacks inherent in infectious disease dynamics, individual immunity has a long shadow: infection of one individual simultaneously increases the
