ArticleProceedings of the National Academy of Sciences of the United States of America2021
Measuring the scientific effectiveness of contact tracing: Evidence from a natural experiment.
Article in Proceedings of the National Academy of Sciences of the United States of America, 2021. The graph could read no effect estimate from its abstract, so it casts no vote on the map. Cited by 35 papers, 5 of them syntheses that pooled it.
What it found
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The abstract states no effect estimate the extractor could read, or names no intervention and outcome on the map, so this paper lights no cell and moves no belief. It is still indexed, cited and linked below.
The trial behind it
Trials whose registry record cites this paper, or whose number appears in the abstract. A trial that started after this paper was published is citing it as background, not reporting it.
Neither the registry nor the abstract names a trial number. If this is a trial report, that itself is worth knowing.
Who cites it
35 citing papers in PubMed, 5 syntheses or guidelines pooled it.
- The Effectiveness of Contact Tracing to Reduce Transmission of Infectious Diseases During Epidemic or Pandemic Response: Rapid Systematic Review.JMIR public health and surveillance · 2026Pooled it
- Effectiveness of testing, contact tracing and isolation interventions among the general population on reducing transmission of SARS-CoV-2: a systematic review.Philosophical transactions. Series A, Mathematical, physical, and engineering sciences · 2023Pooled it
- COVID-19 Contact Tracing Strategies During the First Wave of the Pandemic: Systematic Review of Published Studies.JMIR public health and surveillance · 2023Pooled it
- Effectiveness of contact tracing in the control of infectious diseases: a systematic review.The Lancet. Public health · 2022Pooled it
- Digital Contact Tracing Applications against COVID-19: A Systematic Review.Medical principles and practice : international journal of the Kuwait University, Health Science Centre · 2022Pooled it
- From Bites to Bytes: Evaluating User Engagement and Mosquito Bite Exposure Patterns with the Bite Diary Smartphone Application.The American journal of tropical medicine and hygiene · 2025Article
- Using natural experiments to evaluate population health and health system interventions: new framework for producers and users of evidence.BMJ (Clinical research ed.) · 2025Article
- Optimizing contact tracing for avian influenza in poultry flocks.Journal of the Royal Society, Interface · 2025Article
- Spatio-temporal forecasting of COVID-19 cases in the Netherlands for source and contact tracing.International journal of population data science · 2025Article
- Short, stringent lockdowns halted SARS-CoV-2 transmissions in Danish municipalities.Scientific reports · 2024Article
- [Comparative Analysis of International Coronavirus Disease 2019 Contact-Tracing, Isolation, and Quarantine (TIQ) Policies and Simulation of Policy Effects].Jugan geon-gang gwa jilbyeong · 2024Article
- A Bayesian multivariate factor analysis model for causal inference using time-series observational data on mixed outcomes.Biostatistics (Oxford, England) · 2024Article
- Non-pharmaceutical interventions to reduce COVID-19 transmission in the UK: a rapid mapping review and interactive evidence gap map.Journal of public health (Oxford, England) · 2024Review
- Sociodemographic characteristics and COVID-19 testing rates: spatiotemporal patterns and impact of test accessibility in Sweden.European journal of public health · 2024Article
- Evaluation of the implementation of a community health worker-led COVID-19 contact tracing intervention in Chiapas, Mexico, from March 2020 to December 2021.BMC health services research · 2024Observational
- 'Skin in the Game:' Social Goals Implementation Intentions Increase Intentions to Comply with COVID-19 Preventive Measures.International review of social psychology · 2024Article
- Identifying the interplay between protective measures and settings on the SARS-CoV-2 transmission using a Bayesian network.PloS one · 2024Article
- COVID-19 contact tracing and quarantine policies in the Indo-Pacific Region: A mixed-methods study of experiences of public health professionals.PLOS global public health · 2024Article
- A Retrospective Analysis of Jordan's National COVID-19 Call Center: Operations, Effectiveness, and Lessons Learned.Journal of multidisciplinary healthcare · 2024Article
- Article
Corrections and comments
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Authors and funding
2 authors.
Funding
No grant is acknowledged in the PubMed record.
Abstract
Contact tracing has for decades been a cornerstone of the public health approach to epidemics, including Ebola, severe acute respiratory syndrome, and now COVID-19. It has not yet been possible, however, to causally assess the method's effectiveness using a randomized controlled trial of the sort familiar throughout other areas of science. This study provides evidence that comes close to that ideal. It exploits a large-scale natural experiment that occurred by accident in England in late September 2020. Because of a coding error involving spreadsheet data used by the health authorities, a total of 15,841 COVID-19 cases (around 20% of all cases) failed to have timely contact tracing. By chance, some areas of England were much more severely affected than others. This study finds that the random breakdown of contact tracing led to more illness and death. Conservative causal estimates imply that, relative to cases that were initially missed by the contact tracing system, cases subject to proper contact tracing were associated with a reduction in subsequent new infections of 63% and a reduction insubsequent COVID-19-related deaths of 66% across the 6 wk following the data glitch.
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