Combatting SARS-CoV-2 With Digital Contact Tracing and Notification: Navigating Six Points of Failure

Joanna Masel, James Ian Mackie Petrie, Jason Bay, Wolfgang Ebbers, Aalekh Sharan, Scott Michael Leibrand, Andreas Gebhard, Samuel Zimmerman

Research output: Contribution to journalShort surveypeer-review

1 Scopus citations


Digital contact tracing and notification were initially hailed as promising strategies to combat SARS-CoV-2; however, in most jurisdictions, they did not live up to their promise. To avert a given transmission event, both parties must have adopted the technology, it must detect the contact, the primary case must be promptly diagnosed, notifications must be triggered, and the secondary case must change their behavior to avoid the focal tertiary transmission event. If we approximate these as independent events, achieving a 26% reduction in the effective reproduction number Rt would require an 80% success rate at each of these 6 points of failure. Here, we review the 6 failure rates experienced by a variety of digital contact tracing and contact notification schemes, including Singapore’s TraceTogether, India’s Aarogya Setu, and leading implementations of the Google Apple Exposure Notification system. This leads to a number of recommendations, for example, that the narrative be framed in terms of user autonomy rather than user privacy, and that tracing/notification apps be multifunctional and integrated with testing, manual contact tracing, and the gathering of critical scientific data.

Original languageEnglish (US)
Article numbere49560
JournalJMIR Public Health and Surveillance
Issue number1
StatePublished - Jan 2023


  • contact tracing
  • COVID-19
  • decentralized protocols
  • mobile phone
  • pandemic preparedness
  • SARS-CoV-2
  • smartphone

ASJC Scopus subject areas

  • Health Informatics
  • Public Health, Environmental and Occupational Health


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