Epidemic control with digital contact tracing

The infectiousness of COVID-19 and the high proportion of transmissions from presymptomatic individuals, controlling the epidemic by manual contact tracing is infeasible. The use of a contact-tracing app that builds a memory of proximity contacts and immediately notifies contacts of positive cases would be sufficient to stop the epidemic if used by enough people, in particular when combined with other measures such as physical distancing1.

The proximity of contacts can be achieved by using Bluetooth or geolocation data present in smartphones. But the use of such applications to provide authorities with a complete picture of where people have been, with whom, and for how long, raises privacy concerns2. To achieve the required adoption for these apps to be effective we need to ensure that implementations preserve the privacy of their users and that they safeguarding users against unwarranted discrimination and surveillance3.

In July Ireland became the latest European country to successfully launch a national contact-tracing app designed to support the manual program of tracking down and warning people who have been in contact with someone who has tested positive for COVID-19. A spokesperson for Ireland’s Health Service Executive said “Supporting the development of the technology, a program of public health research has been completed to ensure the app is easy to use, protects privacy, and supports users over time.” and “Employing the decentralized model using the Google/Apple API fully aligns the Irish app with the privacy principles and public health guidance issued by the EU Commission, the OECD, the WHO and the European Center for Disease Prevention and Control.”4.

To help propagate this technology the source code of an application that uses the exposure notification technology provided by Apple and Google on GitHub and a poster of how it works has been made available for public use.

  1. Ferretti, L. et al. Quantifying SARS-CoV-2 transmission suggests epidemic control with digital contact tracing. Science 368, Download (2020).
  2. Israeli contact tracing app raises privacy concerns in US. The Jerusalem Post | JPost.com.
  3. Joint Statement on Contact Tracing. Download (2020).
  4. Leprince-Ringuet, D. Contact tracing: Ireland launches its app following Apple and Google’s model. ZDNet .
  5. COVID Shield. GitHub .
  6. Protecting Lives & Liberty: How Contact Tracing Can Foil COVID-19 & Big Brother.

Video Resources

How the application works

How to install the application

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  1. Hi Wilf, this is good information and the video is helpful. How are positive cases confirmed and the providence of the result assured in the app? At a glance it looks like the app is relying on users to report their status. Is this correct? Is there a means of connecting lab results to the tracker directly? How does alert function ensure relative confidence that the index case is a confirmed case?