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Estimation of reproduction numbers in real time: Conceptual and statistical challenges.

Published version
Peer-reviewed

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Authors

Birrell, Paul J 
Overton, Christopher E  ORCID logo  https://orcid.org/0000-0002-8433-4010
Scarabel, Francesca  ORCID logo  https://orcid.org/0000-0003-0250-4555

Abstract

The reproduction number R has been a central metric of the COVID-19 pandemic response, published weekly by the UK government and regularly reported in the media. Here, we provide a formal definition and discuss the advantages and most common misconceptions around this quantity. We consider the intuition behind different formulations of R , the complexities in its estimation (including the unavoidable lags involved), and its value compared to other indicators (e.g. the growth rate) that can be directly observed from aggregate surveillance data and react more promptly to changes in epidemic trend. As models become more sophisticated, with age and/or spatial structure, formulating R becomes increasingly complicated and inevitably model-dependent. We present some models currently used in the UK pandemic response as examples. Ultimately, limitations in the available data streams, data quality and time constraints force pragmatic choices to be made on a quantity that is an average across time, space, social structure and settings. Effectively communicating these challenges is important but often difficult in an emergency.

Description

Funder: Alan Turing Institute; Id: http://dx.doi.org/10.13039/100012338


Funder: Alexander von Humboldt‐Stiftung; Id: http://dx.doi.org/10.13039/100005156


Funder: Economic and Social Research Council; Id: http://dx.doi.org/10.13039/501100000269


Funder: National Institute for Health Research; Id: http://dx.doi.org/10.13039/501100000272

Keywords

growth rate, real‐time estimation, reproduction numbers

Journal Title

J R Stat Soc Ser A Stat Soc

Conference Name

Journal ISSN

0964-1998
1467-985X

Volume Title

Publisher

Oxford University Press (OUP)
Sponsorship
MRC (via University of Warwick) (MR/V038613/1)