Question

Question 1. Use the disease transmission model as a basis for responding to the three following multipart questions. Your answers are expected to be qualitative or semi-quantitative (e.g. more or less, higher or lower, faster or slower) only. (C) What is ‘herd immunity’? Explain. Then explain the concept of the threshold population size of susceptible individuals (ST) and how this concept, in the context of the disease transmission model, relates to or explains ‘herd immunity’.

Answer 1

In terms of disease transmission model, A diseases that reaches threshold population level of susceptible individuals will be considered as epidemic. If there is epidemic disease spread, it can be controlled by herd immunity that is maximum number of people resistant to the infection by previous exposure of the disease causing material either by vaccination or by previous disease incidence

A person might get immune to the disease causing agent by host immune response if he is previously exposed to the same agent by infection or through other means.