Bidirectional contact tracing could dramatically improve COVID-19 control
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Abstract
Contact tracing is critical to controlling COVID-19, but most protocols only “forward-trace” to notify people who were recently exposed. Using a stochastic branching-process model, we find that “bidirectional” tracing to identify infector individuals and their other infectees robustly improves outbreak control. In our model, bidirectional tracing more than doubles the reduction in effective reproduction number ( R eff ) achieved by forward-tracing alone, while dramatically increasing resilience to low case ascertainment and test sensitivity. The greatest gains are realised by expanding the manual tracing window from 2 to 6 days pre-symptom-onset or, alternatively, by implementing high-uptake smartphone-based exposure notification; however, to achieve the performance of the former approach, the latter requires nearly all smartphones to detect exposure events. With or without exposure notification, our results suggest that implementing bidirectional tracing could dramatically improve COVID-19 control.
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SciScore for 10.1101/2020.05.06.20093369: (What is this?)
Please note, not all rigor criteria are appropriate for all manuscripts.
Table 1: Rigor
NIH rigor criteria are not applicable to paper type.Table 2: Resources
No key resources detected.
Results from OddPub: Thank you for sharing your code.
Results from LimitationRecognizer: We detected the following sentences addressing limitations in the study:Despite this stress-testing, our conclusions must be considered in the context of our model, which, while less idealized than its predecessors, has limitations. It makes no distinction between mild and severe symptoms, and does not consider demographic, geospatial or behavioural variation between cases. Since only true cases are included in the model, only the sensitivity of testing is considered; in reality, the balance between test …
SciScore for 10.1101/2020.05.06.20093369: (What is this?)
Please note, not all rigor criteria are appropriate for all manuscripts.
Table 1: Rigor
NIH rigor criteria are not applicable to paper type.Table 2: Resources
No key resources detected.
Results from OddPub: Thank you for sharing your code.
Results from LimitationRecognizer: We detected the following sentences addressing limitations in the study:Despite this stress-testing, our conclusions must be considered in the context of our model, which, while less idealized than its predecessors, has limitations. It makes no distinction between mild and severe symptoms, and does not consider demographic, geospatial or behavioural variation between cases. Since only true cases are included in the model, only the sensitivity of testing is considered; in reality, the balance between test sensitivity and specificity is a crucial trade-off, and high rates of false positives will severely impede response effectiveness and the credibility of the tracing system. These limitations aside, there is considerable evidence that bidirectional tracing can be feasibly implemented in practice. Locales such as Singapore13,14 and Washington State28 have employed bidirectional tracing to determine whether community transmission is occurring, while Japan’s protocol explicitly aims to identify sources of infection12. The primary practical difference between contact with an infector and an infectee is the time at which the contact occurred; as such, the core obstacle to implementation in other areas is the cost of expanding the tracing window. Health authorities could accomplish this by expanding the workforce of contact tracers, leveraging the lightened workload afforded by a high-uptake digital system, or focusing limited resources on clusters as is done in Japan. Digital systems, which already track exposures for 14 days, can trace bidirectionally...
Results from TrialIdentifier: No clinical trial numbers were referenced.
Results from Barzooka: We did not find any issues relating to the usage of bar graphs.
Results from JetFighter: We did not find any issues relating to colormaps.
Results from rtransparent:- Thank you for including a conflict of interest statement. Authors are encouraged to include this statement when submitting to a journal.
- Thank you for including a funding statement. Authors are encouraged to include this statement when submitting to a journal.
- No protocol registration statement was detected.
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