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. 2020 Nov;53(6):405-408.
doi: 10.3961/jpmph.20.288. Epub 2020 Oct 20.

Interpretation of the Basic and Effective Reproduction Number

Jun-Sik Lim  1 , Sung-Il Cho  2 , Sukhyun Ryu  3 , Son-Il Pak  1
Affiliations

Interpretation of the Basic and Effective Reproduction Number

Jun-Sik Lim et al. J Prev Med Public Health. 2020 Nov.

Abstract

In epidemiology, the basic reproduction number (R0) is a term that describes the expected number of infections generated by 1 case in a susceptible population. At the beginning of the coronavirus disease 2019 (COVID-19) pandemic, R0 was frequently referenced by the public health community and the wider public. However, this metric is often misused or misinterpreted. Moreover, the complexity of the process of estimating R0 has caused difficulties for a substantial number of researchers. In this article, in order to increase the accessibility of this concept, we address several misconceptions related to the threshold characteristics of R0 and the effective reproduction number (Rt). Moreover, the appropriate interpretation of the metrics is discussed. R0 should be considered as a population-averaged value that pools the contact structure according to a stochastic transmission process. Furthermore, it is necessary to understand the unavoidable time lag for Rt due to the incubation period of the disease.

Keywords: Infectious disease; Public health; Reproduction number; Surveillance.

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Conflict of interest statement

CONFLICT OF INTEREST

The authors have no conflicts of interest associated with the material presented in this paper.

Figures

Figure. 1.
Figure. 1.
Different reporting time points by the surveillance system based on the incidence of symptoms (report 1) and by the one with time lag (report 2).
See this image and copyright information in PMC

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