Quantifying SARS-CoV-2 transmission suggests epidemic control with digital contact tracing

TLDR

SARS‑CoV‑2 causes high fatality and overwhelms health systems, and manual contact tracing alone cannot contain its rapid spread, necessitating faster, scalable digital solutions. The study aims to quantify transmission dynamics to identify isolation and contact‑tracing thresholds for epidemic control and to address the ethical implications of such interventions. The authors model transmission parameters and propose a proximity‑based contact‑tracing app that records contacts and instantly notifies exposed individuals to achieve epidemic control. Targeted digital contact tracing can contain SARS‑CoV‑2 outbreaks without imposing harmful mass lockdowns.

Abstract

The newly emergent human virus SARS-CoV-2 (severe acute respiratory syndrome-coronavirus 2) is resulting in high fatality rates and incapacitated health systems. Preventing further transmission is a priority. We analyzed key parameters of epidemic spread to estimate the contribution of different transmission routes and determine requirements for case isolation and contact tracing needed to stop the epidemic. Although SARS-CoV-2 is spreading too fast to be contained by manual contact tracing, it could be controlled if this process were faster, more efficient, and happened at scale. A contact-tracing app that builds a memory of proximity contacts and immediately notifies contacts of positive cases can achieve epidemic control if used by enough people. By targeting recommendations to only those at risk, epidemics could be contained without resorting to mass quarantines ("lockdowns") that are harmful to society. We discuss the ethical requirements for an intervention of this kind.