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Modelling the Health and Economic Impacts of Population-Wide Testing, Contact Tracing and Isolation (PTTI) Strategies for COVID-19 in the UK

83 Pages Posted: 19 Jun 2020

See all articles by Tim Colbourn

Tim Colbourn

University College London - Institute for Global Health

William Waites

University of Edinburgh - School of Informatics

Jasmina Panovska-Griffiths

University College London - Institute for Global Health

David Manheim

University of Haifa - Health and Risk Communication Research Center

Simone Sturniolo

Science and Technology Facilities Council

Greg Colbourn

Centre for Enabling EA Learning & Research

Cam Bowie

Retired

Keith M. Godfrey

University of Southampton - MRC Lifecourse Epidemiology Unit

Julian Peto

University Hospital Southampton NHS Foundation Trust

Rochelle A. Burgess

University College London - Institute for Global Health

Derek Foster

Rethink Priorities

David McCoy

Queen Mary, University of London

Nisreen A. Alwan

University of Southampton - School of Primary Care and Population Sciences

Guiqing Yao

University of Leicester - Department of Health Sciences

Kang Ouyang

Huazhong University - Institute of State Governance

Paul J. Roderick

University of Southampton - School of Primary Care, Population Sciences and Medical Education

Elena Pizzo

University College London - Department of Applied Health Research

Tony Hill

Retired

Nuala McGrath

University of Southampton - School of Primary Care, Population Sciences and Medical Education

Miriam Orcutt

University College London - Institute for Global Health

Owain Evans

University of Oxford - Future of Humanity Institute

Nathan J. Cheetham

East London Health and Care Partnership - WEL Clinical Commissioning Groups

Mark Sculpher

University of York - Centre for Health Economics

Chris Bonell

London School of Hygiene and Tropical Medicine

Manuel Gomes

University College London - Department of Applied Health Research

Rosalind Raine

University College London - Department of Applied Health Research

More...

Abstract

Background: The COVID-19 epidemic in the UK has resulted in over 280,000 reported cases and over 40,000 deaths as of 5th June 2020. In the context of a slower increase in reported cases and deaths associated with COVID-19 over the last few weeks compared to earlier in the epidemic, the UK is starting to relax the physical restrictions (‘lockdown’) that have been imposed since 23 March 2020. This has been accompanied by the announcement of a strategy to test people for infection, trace contacts of those tested positive, and isolate positive diagnoses. While such policies are expected to be impactful, there is no conclusive evidence of which approach to this is likely to achieve the most appropriate balance between benefits and costs. This study combines mathematical and economic modelling to estimate the impact, costs, feasibility, and health and economic effects of different strategies.

Methods: We provide detailed description, impact, costing, and feasibility assessment of population-scale testing, tracing, and isolation strategies (PTTI). We estimate the impact of different PTTI strategies with a deterministic mathematical model for SARS-CoV-2 transmission that accurately captures tracing and isolation of contacts of individuals exposed, infectious, and diagnosed with the virus. We combine this with an economic model to project the mortality, intensive care, hospital, and non-hospital case outcomes, costs to the UK National Health Service, reduction in GDP, and intervention costs of each strategy. Model parameters are derived from publicly available data, and the model is calibrated to reported deaths associated with COVID-19. We modelled 31 scenarios in total (Panel 2). The first 18 comprised nine with ‘triggers’ (labelled with the -Trig suffix) for subsequent lockdown periods (>40,000 new infections per day) and lockdown releases (<10,000 new infections per day), and nine corresponding scenarios without triggers, namely: no large-scale PTTI (scenario 1); scale-up of PTTI to testing the whole population every week, with May–July 2020 lockdown release (scenario 2b), or delayed lockdown release until scale-up complete on 31 August 2020 (scenario 2a); these two scenarios with mandatory use of face coverings (scenarios 3a and 3b); and scenarios 2a, 2b, 3a, 3b replacing untargeted PTTI with testing of symptomatic people only (scenarios 4a, 4b, 4c, 4d). The final 13 scenarios looked at: whole population weekly testing to suppress the epidemic with lower tracing success (scenarios 3b-Trig00, 3b-Trig10, 3b-Trig20, 3b-Trig30) and switched to targeted testing after two months when it may suppress the epidemic (scenarios 3b-Trig00-2mo and 3b-Trig30-2mo), and targeted testing with lower tracing success (scenarios 4d-Trig10, 4dTrig20, 4d-Trig30, 4d-Trig40, 4d-Trig50, 4d-Trig60, 4d-Trig70).

Findings: Given that physical distancing measures have already been relaxed in the UK, scenario 4d-Trig (targeted testing of symptomatic people only, with a mandatory face coverings policy and subsequent lockdown triggered to enable PTTI to suppress the epidemic), is a strategy that will result in the fewest deaths (~52,000) and has the lowest intervention costs (~£8bn). The additional lockdown results in total reduction in GDP of ~£503bn, less than half the cost to the economy of subsequent lockdowns triggered in a scenario without PTTI (scenario 1-Trig, ~£1180bn reduction in GDP, ~105,000 deaths). In summer months, with lower cold and flu prevalence, approximately 75,000 symptomatic people per day need to be tested for this strategy to work, assuming 64% of their contacts are effectively traced (~80% traced with 80% success) within the infectious period (most within the first two days and nearly all by seven days) and all are isolated – including those without any symptoms – for 14 days. Untargeted testing of everyone every week, if it were feasible, may work without tracing, but at a higher cost (scenario 3b-Trig00). This cost could be reduced by switching to targeted testing after the epidemic is suppressed (scenario 3b-Trig30-2mo), though we note the epidemic could be suppressed with targeted testing itself providing tracing and isolation has at least a 32% success rate (scenario 4dTrig40).

Interpretation: PTTI strategies to suppress the COVID-19 epidemic within the context of a relaxation of lockdown will necessitate subsequent lockdowns to keep the epidemic suppressed during PTTI scale-up. Targeted testing of symptomatic people only can suppress the epidemic if accompanied by mandated use of face coverings. The feasibility of PTTI depends on sufficient capacity, capabilities, infrastructure and integrated systems to deliver it. The political and public acceptability of alternative scenarios for subsequent lockdowns needs to take account of crucial implications for employment, personal and national debt, education, population mental health and non-COVID-19 disease. Our model is able to incorporate additional scenarios as the situation evolves.

Funding: No specific funding was received in support of this study. Grant support for specific authors is as follows: WW acknowledges support from the Chief Scientist Office (COV/EDI/20/12) RR, JPG and EP are supported by the National Institute for Health Research ARC North Thames. NMcG is a recipient of an NIHR Global Health Research Professorship award (Ref: RP-2017-08-ST2-008). The views expressed in this independent research are those of the authors and not necessarily those of the National Institute for Health Research or the Department of Health and Social Care. KMG is supported by the UK Medical Research Council (MC_UU_12011/4), the National Institute for Health Research (NIHR Senior Investigator (NF-SI-0515-10042) and NIHR Southampton Biomedical Research Centre (IS-BRC-1215-20004)), British Heart Foundation (RG/15/17/3174) and the US National Institute On Aging of the National Institutes of Health (Award No. U24AG047867). GY acknowledges her research partially supported from the Newton Fund through a UK-China ARM Partnership Hub award (No:MR/S013717/1).

Declaration of Interests: All authors declare no competing interests.

Keywords: Testing, tracing and isolation, COVID-19, Epidemic suppression, economic evaluation, policy options

Suggested Citation

Colbourn, Tim and Waites, William and Panovska-Griffiths, Jasmina and Manheim, David and Sturniolo, Simone and Colbourn, Greg and Bowie, Cam and Godfrey, Keith M. and Peto, Julian and Burgess, Rochelle A. and Foster, Derek and McCoy, David and Alwan, Nisreen A. and Yao, Guiqing and Ouyang, Kang and Roderick, Paul J. and Pizzo, Elena and Hill, Tony and McGrath, Nuala and Orcutt, Miriam and Evans, Owain and Cheetham, Nathan J. and Sculpher, Mark and Bonell, Chris and Gomes, Manuel and Raine, Rosalind, Modelling the Health and Economic Impacts of Population-Wide Testing, Contact Tracing and Isolation (PTTI) Strategies for COVID-19 in the UK (6/10/2020). Available at SSRN: https://ssrn.com/abstract=3627273 or http://dx.doi.org/10.2139/ssrn.3627273

Tim Colbourn (Contact Author)

University College London - Institute for Global Health ( email )

United Kingdom

William Waites

University of Edinburgh - School of Informatics

Old College
South Bridge
Edinburgh, Scotland EH8 9JY
United Kingdom

Jasmina Panovska-Griffiths

University College London - Institute for Global Health

United Kingdom

David Manheim

University of Haifa - Health and Risk Communication Research Center

Mount Carmel
Haifa, 31905
Israel

Simone Sturniolo

Science and Technology Facilities Council

Harwell Oxford, Didcot
United Kingdom

Greg Colbourn

Centre for Enabling EA Learning & Research

Cam Bowie

Retired

Keith M. Godfrey

University of Southampton - MRC Lifecourse Epidemiology Unit

University Rd.
Southampton SO17 1BJ, Hampshire SO17 1LP
United Kingdom

Julian Peto

University Hospital Southampton NHS Foundation Trust

University Rd.
Southampton SO17 1BJ, Hampshire SO17 1LP
United Kingdom

Rochelle A. Burgess

University College London - Institute for Global Health

United Kingdom

Derek Foster

Rethink Priorities

David McCoy

Queen Mary, University of London ( email )

Lincoln's Inn Fields
Mile End Rd.
London, E1 4NS
United Kingdom

Nisreen A. Alwan

University of Southampton - School of Primary Care and Population Sciences

Southampton
United Kingdom

Guiqing Yao

University of Leicester - Department of Health Sciences

Adrian Building
Leicester, LE1 7RH
United Kingdom

Kang Ouyang

Huazhong University - Institute of State Governance

Paul J. Roderick

University of Southampton - School of Primary Care, Population Sciences and Medical Education

University Rd.
Southampton SO17 1BJ, Hampshire SO17 1LP
United Kingdom

Elena Pizzo

University College London - Department of Applied Health Research

Gower
London, WC1E 6BT
United Kingdom

Tony Hill

Retired

Nuala McGrath

University of Southampton - School of Primary Care, Population Sciences and Medical Education ( email )

University Rd.
Southampton SO17 1BJ, Hampshire SO17 1LP
United Kingdom

Miriam Orcutt

University College London - Institute for Global Health

United Kingdom

Owain Evans

University of Oxford - Future of Humanity Institute

Suite 8, Littlegate House
16/17 St Ebbe's Street
Oxford, OX1 1PT
United Kingdom

Nathan J. Cheetham

East London Health and Care Partnership - WEL Clinical Commissioning Groups

Mark Sculpher

University of York - Centre for Health Economics

York YO10 5DD
United Kingdom

Chris Bonell

London School of Hygiene and Tropical Medicine

Keppel Street
London, WC1E 7HT
United Kingdom

Manuel Gomes

University College London - Department of Applied Health Research

Gower
London, WC1E 6BT
United Kingdom

Rosalind Raine

University College London - Department of Applied Health Research

Gower
London, WC1E 6BT
United Kingdom

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