A phased approach to unlocking during the COVID‐19 pandemic—Lessons from trend analysis
Authors: Mark Davies
Mark Lunt
Simon G Anderson
Adrian H Heald
Arpana Verma
Mike Stedman
Journal: International Journal of Clinical Practice (2020)
Discipline: CLINICAL MEDICINE
Keywords: COVID-19 pandemic; infection rates; policy impact; data trends; Average Daily Infection Rate (ADIR)
Affiliations: Res Consortium, Andover, UK., Division of Musculoskeletal and Dermatological Sciences, University of Manchester, Manchester, UK., Population Health, Health Services Research and Primary Care, The University of Manchester, Manchester, UK., University of the West Indies, Cave Hill, Barbados., Division of Cardiovascular Sciences, Faculty of Biology, Medicine and Health, The University of Manchester, Manchester, UK., Department of Diabetes and Endocrinology, Salford Royal Hospital, Salford, UK., The Faculty of Biology, Medicine and Health and Manchester Academic Health Sciences Centre, University of Manchester, Manchester, UK.

Abstract:  Background: The COVID-19 pandemic has led to radical political control of social behaviour. The purpose of this paper is to explore data trends from the pandemic regarding infection rates/policy impact, and draw learning points for informing the unlocking process. Methods: The daily published cases in England in each of 149 Upper Tier Local Authority (UTLA) areas were converted to Average Daily Infection Rate (ADIR), an R-value - the number of further people infected by one infected person during their infectious phase with Rate of Change of Infection Rate (RCIR) also calculated. Stepwise regression was carried out to see what local factors could be linked to differences in local infection rates FINDINGS: By the 19th April 2020 the infection R has fallen from 2.8 on 23rd March before the lockdown and has stabilised at about 0.8, sufficient for suppression. However there remain significant variations between England regions. Regression analysis across UTLAs found that the only factor relating to reduction in ADIR was the historic number of confirmed number infection/000 population, There is however wide variation between Upper Tier Local Authorities (UTLA) areas. Extrapolation of these results showed that unreported community infection may be 150 times higher than reported cases, providing evidence that by the end of the second week in April, 26.8% of the population may already have had the disease and so have increased immunityExtrapolation of these results showed that unreported community infection may be 150 times higher than reported cases, providing evidence that by the end of the second week in April, 26.8% of the population may already have had the disease and so have increased immunity. Interpretation: Analysis of current case data using infectious ratio has provided novel insight into the current national state and can be used to make better-informed decisions about future management of restricted social behaviour and movement. 

Retracted: No

PubPeer comments:
 Carl T. Bergstrom (famous for teaching the course and writing the book  Calling Bullshit ) has reviewed this publication on Twitter: https: twitter.com CT_Bergstrom status 1261058066495074304 , 
 https: twitter.com timcolbourn status 1261026804216803331 , 
 https: www.sciencemediacentre.org expert-reaction-to-study-reporting-the-suggestion-that-25-of-people-in-the-uk-are-likely-to-have-already-been-infected-by-the-covid-19-virus , 
 https: twitter.com ve3hw status 1261019169270697987 , 
 https: twitter.com bioinformagic status 1261199457858789377 , 
 The reported case and death numbers for 24th April are not referenced and do not appear to match the figures on multiple tracking websites. , 
 Without a table of descriptives, we cannot know to what extent the beta coefficient for the main predictor of interest may have been affected by the inclusion in the regression model of what seems like a somewhat arbitrary selection of covariates, some of which will likely have been quite strongly correlated among themselves (e.g.  Urban Rural with  Ethnicity: White British , or  % Individual with Age 60 with  % population with Longer term conditions ), which has the potential to lead to suppression effects (standardized regression coefficients greater in magnitude than, or of opposite sign to, the corresponding zero-order correlations). , 
 The statistician of the Financial Times, John Burn-Murdoch: https: twitter.com jburnmurdoch status 1261222810992685056 , 
 https: steamtraen.blogspot.com 2020 05 the-perils-of-improvising-with-linear.html , 
 There is a preprint version of this article here: https: www.medrxiv.org content 10.1101 2020.04.20.20072264v1 In the preprint, the regression equation (using data from 11 days than the data that were was used in the accepted manuscript) is RADIR = 1.20 - 0.26 x Current Total Cases 1,000 compared to RADIR = 1.06 - 0.16 x Current Total Cases 1,000 in the accepted manuscript. But the whole point of the model is the assumption that the slope of the regression will remain constant over time. Why did the authors not modify this assumption when their own data provided them with concrete evidence that it was untenable? , 
 https: www.open.edu openlearn science-maths-technology biology covid-19-making-decisions-based-on-flawed-statistics ,