What the reproductive number R0 can and cannot tell us about COVID-19 dynamics

Clara L. Shaw, David A. Kennedy

Research output: Contribution to journalComment/debatepeer-review

21 Scopus citations


The reproductive number R (or R0, the initial reproductive number in an immune-naïve population) has long been successfully used to predict the likelihood of pathogen invasion, to gauge the potential severity of an epidemic, and to set policy around interventions. However, often ignored complexities have generated confusion around use of the metric. This is particularly apparent with the emergent pandemic virus SARS-CoV-2, the causative agent of COVID-19. We address some misconceptions about the predictive ability of the reproductive number, focusing on how it changes over time, varies over space, and relates to epidemic size by referencing the mathematical definition of R and examples from the current pandemic. We hope that a better appreciation of the uses, nuances, and limitations of R and R0 facilitates a better understanding of epidemic spread, epidemic severity, and the effects of interventions in the context of SARS-CoV-2.

Original languageEnglish (US)
Pages (from-to)2-9
Number of pages8
JournalTheoretical Population Biology
StatePublished - Feb 2021

All Science Journal Classification (ASJC) codes

  • Ecology, Evolution, Behavior and Systematics


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