Quantifying dynamics of SARS-CoV-2 transmission suggests that epidemic control and avoidance is feasible through instantaneous digital contact tracing

Luca Ferretti; Chris Wymant; Michelle Kendall; Lele Zhao; Anel Nurtay; David G Bonsall; Christophe Fraser

The copyright holder for this preprint (which was not peer-reviewed) is . https://doi.org/10.1101/2020.03.08.20032946 doi: medRxiv preprint our infectiousness model above, i.e., quantifying how the SARS-CoV-2 epidemic is expected to be controlled or not by case isolation and the quarantining of traced contacts. Our results are shown in Fig. 3 . The black line shows the threshold for epidemic control: combined success rates in the region to the upper right of the black line are sufficient to reduce R to less than one. The x axis is the success rate of case isolation, which can be thought of either as the fraction of symptomatic individuals isolated, assuming perfect prevention of transmission on isolation, or the degree to which infectiousness of symptomatic individuals is reduced assuming all of them are isolated. The y axis is the success rate of contact tracing; similarly, this can be thought of as the fraction of all contacts traced, assuming perfectly successful quarantine upon tracing, or the degree to which infectiousness of contacts is reduced assuming all of them are traced. These results for intervention effectiveness, and their dependence on all parameters in our combined analysis, can be explored through the same involves the minimum imposition possible and that decisions in policy and practice are guided by three moral values: equal moral respect, fairness, and the importance of reducing suffering (28) . It is noteworthy that the algorithmic approach we propose avoids the need for coercive surveillance, since the system can have very large impacts and achieve sustained epidemic suppression, even with partial uptake. People should be democratically entitled to decide whether to adopt this platform. The intention is not to impose the technology as a permanent change to society, but we believe it is under these pandemic circumstances it is necessary and justified to protect public health.