EFFECTIVE REPRODUCTION NUMBER AS INDICATOR OF HERD IMMUNITY TO SARS-CoV-2

Abstract

Based on the mean basic reproduction number (R-0 = 4.26) for SARS-CoV-2, the global and individual values of the effective reproduction number (R) were determined for the ten leading countries in terms of vaccination against the novel coronavirus infection as of December 16-21, 2021. The calculation of R made it possible to distinguish two clusters of countries for this indicator: (i) in the world as a whole, as well as seven countries (India, USA, Indonesia, Germany, Mexico, Russia, Pakistan) had R > 1, which does not allow us to discuss about the development of herd immunity;(ii) three countries (China, Brazil, Japan) have reached R < 1, which allows us to discuss about the prerequisites for the development of herd immunity. The relationship between the effective reproduction number and the share of population vaccinated is discussed. The herd immunity threshold to SARS-CoV-2 is determined at the level of 76.5%, which is achieved at R-0 = 4.26 and R = 1.