Majmaah Journal of Health Sciences ,Vol. 9, Issue 1, January - 2021, Jumadi ul Awwal - 1442 1 Herd Immunity could save the world from COVID-19! Letter to editor: Herd Immunity could save the world from COVID-19! Abdul Sattar Khan 1 1. Head & Assistant Professor, Family & Community Medicine Department. College of Medicine, King Faisal University Received on 1st July, 2020 and accepted on 29th July 2020 (dx.doi.org/10.5455/mjhs.2021.01.002) Corresponding Author: Dr. Abdul Sattar Khan, Head & Assistant Professor, Family & Community Medicine Department. College of Medicine, King Faisal University. Email.amkhan@kfu.edu.sa Sir, many strategies have been applied to break the spread and management of COVID 19 after declaring the pandemic of COVID 19. [1] These debates extended to the arguments of the economy and even- tually about herd immunity. [2] This herd immunity is a strategy to allow the infec- tion to spread into the population at a cer- tain level, but at the same time protects the most vulnerable age group or with co-mor- bidities. [3] There are many issues pinned up with all kinds of strategies for controlling this deadly virus, and every strategy has its own consequences. Moreover, these con- sequences are indeed different in different countries depending upon their circum- stances. Thus, it is stated precisely, there is no thumb rule, which can be applied to all countries straightforwardly. However, before initiating any strategy, there is a need to check the basic reproductive rate or number (R0), or concisely the real-life effective reproductive number (Rt) for a given community. [4] Many articles have been written for these estimations and all calculations are available for all countries. Here it is needed to just overview these es- timations for some developing countries where still a peak is awaited, and cases are increasing rapidly. To pursue for the further discussion, we need to calculate the minimum percentage (Y) of population required to be immune for realizing herd immunity. [4] and for this estimation, we may use this formula [Y= (R0-1) / R0 X 100]. These estimates may not be applicable to all countries and even seems higher in the whole world because those patients who have COV- ID-19 depict mild symptoms or could go undetected and improve in two to three weeks. This could be similar to the case of SARS-CoV-2 for instance and might describes why some individuals (perhaps a group of people recently recovered from the seasonal viral infection) may present