With the COVID-19 cases increasing day by day, the theory of herd immunity has been frequently being used
What is Herd Immunity?
It is a form of indirect protection from infectious disease that occurs when a large percentage of a population has become immune to an infection, thereby providing a measure of protection for individuals who are not immune.
Initially, herd immunity, an important tool in epidemic control, was proposed as a means to overcome the pandemic.
Since a vaccine is not available for COVID-19 yet, some people advocated that the infection be allowed to spread in the community until herd immunity is achieved.
Only a certain proportion of the population needs to be infected in order to stop large outbreaks, either through naturally-acquired disease, or through vaccination.
How and when will herd immunity be achieved in this pandemic?
Herd immunity is achieved when one infected person in a population generates less than one secondary case on an average
This corresponds to the effective reproduction number R (that is, the average number of persons infected by a case) dropping below 1 in the absence of interventions