The effectiveness of backward contact tracing in networks

Kojaku, Sadamori; Hébert‐Dufresne, Laurent; Mones, Enys; Lehmann, Sune; Ahn, Yong‐Yeol

doi:10.1038/s41567-021-01187-2

Cited by 118 publications

(120 citation statements)

References 45 publications

(58 reference statements)

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“…However, even with just forward tracing, epidemic control is still theoretically achievable. Several recent studies have produced similar findings 26,29,30 .…”

Section: Resultssupporting

confidence: 66%

Controlling COVID-19 via test-trace-quarantine

et al. 2021

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Initial COVID-19 containment in the United States focused on limiting mobility, including school and workplace closures. However, these interventions have had enormous societal and economic costs. Here, we demonstrate the feasibility of an alternative control strategy, test-trace-quarantine: routine testing of primarily symptomatic individuals, tracing and testing their known contacts, and placing their contacts in quarantine. We perform this analysis using Covasim, an open-source agent-based model, which has been calibrated to detailed demographic, mobility, and epidemiological data for the Seattle region from January through June 2020. With current levels of mask use and schools remaining closed, we find that high but achievable levels of testing and tracing are sufficient to maintain epidemic control even under a return to full workplace and community mobility and with low vaccine coverage. The easing of mobility restrictions in June 2020 and subsequent scale-up of testing and tracing programs through September provided real-world validation of our predictions. Although we show that test-trace-quarantine can control the epidemic in both theory and practice, its success is contingent on high testing and tracing rates, high quarantine compliance, relatively short testing and tracing delays, and moderate to high mask use. Thus, in order for test-trace-quarantine to control transmission with a return to high mobility, strong performance in all aspects of the program is required.

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“…However, even with just forward tracing, epidemic control is still theoretically achievable. Several recent studies have produced similar findings 26,29,30 .…”

Section: Resultssupporting

confidence: 66%

Controlling COVID-19 via test-trace-quarantine

et al. 2021

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“…Unlike forward tracing, backward tracing is more effective when the number of onward transmissions is highly variable, because index cases are disproportionately more likely to have been generated by primary cases who also infected others (an example of the "friendship paradox" [7][8][9] ). Because there is evidence that the number of secondary transmissions of SARS-CoV-2 per case exhibits substantial individual-level variation (i.e.…”

Section: Introductionmentioning

confidence: 99%

“…overdispersion), often resulting in so-called superspreading events [10][11][12] , a large proportion of infections may be linked to a small proportion of original clusters. As a result, finding and targeting originating clusters in combination with reducing onwards infection may substantially enhance the effectiveness of tracing methods 9,13,14 .…”

Section: Introductionmentioning

confidence: 99%

Implication of backward contact tracing in the presence of overdispersed transmission in COVID-19 outbreaks

et al. 2021

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Introduction: Contact tracing has the potential to control outbreaks without the need for stringent physical distancing policies, e.g. civil lockdowns. Unlike forward contact tracing, backward contact tracing identifies the source of newly detected cases. This approach is particularly valuable when there is high individual-level variation in the number of secondary transmissions (overdispersion). Methods: By using a simple branching process model, we explored the potential of combining backward contact tracing with more conventional forward contact tracing for control of COVID-19. We estimated the typical size of clusters that can be reached by backward tracing and simulated the incremental effectiveness of combining backward tracing with conventional forward tracing. Results: Across ranges of parameter values consistent with dynamics of SARS-CoV-2, backward tracing is expected to identify a primary case generating 3-10 times more infections than a randomly chosen case, typically increasing the proportion of subsequent cases averted by a factor of 2-3. The estimated number of cases averted by backward tracing became greater with a higher degree of overdispersion. Conclusion: Backward contact tracing can be an effective tool for outbreak control, especially in the presence of overdispersion as is observed with SARS-CoV-2.

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“…However, individual contact data can inform network models which are powerful for other purposes, for instance, informing or measuring the impact of interventions and policies, such as school closures and lockdowns (Zhang et al, 2020). Likewise, these network models can be instrumental in guiding real-time contact tracing efforts during epidemics (Firth et al, 2020;Kojaku et al, 2020). One key limitation of this model is that they are often not spatially or temporally explicit.…”

Section: Models and Their Limitationsmentioning

confidence: 99%

Containing Future Epidemics With Trustworthy Federated Systems for Ubiquitous Warning and Response

Carrillo¹,

Nguyen²,

Nardelli³

et al. 2021

Front. Comms. Net.

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In this paper, we propose a global digital platform to avoid and combat epidemics by providing relevant real-time information to support selective lockdowns. It leverages the pervasiveness of wireless connectivity while being trustworthy and secure. The proposed system is conceptualized to be decentralized yet federated, based on ubiquitous public systems and active citizen participation. Its foundations lie on the principle of informational self-determination. We argue that only in this way it can become a trustworthy and legitimate public good infrastructure for citizens by balancing the asymmetry of the different hierarchical levels within the federated organization while providing highly effective detection and guiding mitigation measures toward graceful lockdown of the society. To exemplify the proposed system, we choose a remote patient monitoring as use case. This use case is evaluated considering different numbers of endorsed peers on a solution that is based on the integration of distributed ledger technologies and NB-IoT (narrowband IoT). An experimental setup is used to evaluate the performance of this integration, in which the end-to-end latency is slightly increased when a new endorsed element is added. However, the system reliability, privacy, and interoperability are guaranteed. In this sense, we expect active participation of empowered citizens to supplement the more usual top-down management of epidemics.

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The effectiveness of backward contact tracing in networks

Cited by 118 publications

References 45 publications

Controlling COVID-19 via test-trace-quarantine

Controlling COVID-19 via test-trace-quarantine

Implication of backward contact tracing in the presence of overdispersed transmission in COVID-19 outbreaks

Containing Future Epidemics With Trustworthy Federated Systems for Ubiquitous Warning and Response

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