Cited by 87COVID-19 Digital Contact TracingCOVID-19 epidemiological studiesData-Driven Disease Surveillance

Effective contact tracing for COVID-19: A systematic review

Open access
Juneau, Carl-Etienne, Briand, Anne-Sara, Collazzo, Pablo, Siebert, Uwe, Pueyo, Tomas·2023·Global Epidemiology

Published version of a preprint

Abstract

ABSTRACT Background Contact tracing is commonly recommended to control outbreaks of COVID-19, but its effectiveness is unclear. This systematic review aimed to examine contact tracing effectiveness in the context of COVID-19. Methods Following PRISMA guidelines, MEDLINE, Embase, Global Health, and All EBM Reviews were searched using a range of terms related to contact tracing for COVID-19. Articles were included if they reported on the ability of contact tracing to slow or stop the spread of COVID-19 or on characteristics of effective tracing efforts. Two investigators screened all studies. Results A total of 32 articles were found. All were observational or modelling studies, so the quality of the evidence was low. Observational studies (n=14) all reported that contact tracing (alone or in combination with other interventions) was associated with better control of COVID-19. Results of modelling studies (n=18) depended on their assumptions. Under assumptions of prompt and thorough tracing with no further transmission, they found that contact tracing could stop an outbreak (e.g. by reducing the reproduction number from 2.2 to 0.57) or that it could reduce infections (e.g. by 24%-71% with a mobile tracing app). Under assumptions of slower, less efficient tracing, modelling studies suggested that tracing could slow, but not stop COVID-19. Conclusions Observational and modelling studies suggest that contact tracing is associated with better control of COVID-19. Its effectiveness likely depends on a number of factors, including how many and how fast contacts are traced and quarantined, and how effective quarantines are at preventing further transmission. A cautious interpretation suggests that to stop the spread of COVID-19, public health practitioners have 2-3 days from the time a new case develops symptoms to isolate the case and quarantine at least 80% of its contacts, and that once isolated, cases and contacts should infect zero new cases. Less efficient tracing may slow, but not stop, the spread of COVID-19. Inefficient tracing (with delays of 4-5+ days or less than 60% of contacts quarantined with no further transmission) may not contribute meaningfully to control of COVID-19. Funding LP holds the Canada Research Chair in Community Approaches and Health Inequalities (CRC 950-232541). This funding source had no role in the design, conduct, or reporting of the study. Competing interests CEJ has contractual agreements with the Centre intégré universitaire de santé et de services sociaux du Centre-Sud-de-l’Île-de-Montréal and is founder of Dr. Muscle and the COVID-19 Science Updates ( https://covid1.substack.com/ ). Registration PROSPERO CRD42020198462

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  1. [11]JE McKenzie Brennan S.E. Chapter 12: Synthesizing and presenting findings using other methods JPT Higgins Thomas J. Chandler J. Cumpston M. Li T. Page M.J. Cochrane handbook for systematic reviews of interventions version 6.2 (updated February 2021). Cochrane 2021

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Authors
Juneau, C.-E., Briand, A.-S., Collazzo, P., Siebert, U., & Pueyo, T.
Affiliations
  • Université de Montréal (CA)
  • Universität für Weiterbildung Krems (AT)
  • Harvard University (US)
Corresponding author
Collazzo, Pablo
Venue
Global Epidemiology
Publisher
Elsevier BV
Published
2023-12
Volume
5
Pages
100103
ISSN
2590-1133 (ISSN-L)
OpenAlex
W4323667182
Cited by
85
References
68
Citations by year
2026: 8 · 2025: 12 · 2024: 32 · 2023: 13 · 2022: 10 · 2021: 9 · 2020: 1
FWCI
2.73
Type
journal article
Language
en
Open access
Locations
  • Global Epidemiology (publishedVersion, cc-by)
  • medRxiv (acceptedVersion)
  • PubMed Central (publishedVersion, cc-by)
  • PubMed (publishedVersion)
  • DOAJ (DOAJ: Directory of Open Access Journals) (submittedVersion, cc-by-sa)
Funders
Université de Montréal
Topics
  • Physical Sciences › Computer Science › Information Systems › COVID-19 Digital Contact Tracing
  • Physical Sciences › Mathematics › Modeling and Simulation › COVID-19 epidemiological studies
  • Health Sciences › Medicine › Epidemiology › Data-Driven Disease Surveillance
Keywords
contact tracing, COVID-19 pandemic, quarantine, isolation, reproduction number, disease transmission control, public health interventions

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