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Review article: Biomedical intelligence

Vol. 151 No. 3536 (2021)

The SwissCovid Digital Proximity Tracing App after one year: Were expectations fulfilled?  

  • Paola Daniore
  • Tala Ballouz
  • Dominik Menges
  • Viktor von Wyl
Cite this as:
Swiss Med Wkly. 2021;151:w30031


Digital proximity tracing has been promoted as a major technological innovation for its potential added benefits of greater speed, wider reach and better scalability compared with traditional manual contact tracing. First launched in Switzerland on 25 June 2020, the SwissCovid digital proximity tracing app has now been in use for more than one year. In light of this milestone, we raise the questions: What is currently known about the role of SwissCovid in mitigating the pandemic? Were the expectations fulfilled?

In this review, we will summarise the current state of the literature from empirical studies on the adoption, performance and effectiveness of SwissCovid. The review consists of three sections. The first section summarizes findings from effectiveness studies, which suggest that SwissCovid exposure notifications contributed to preventive actions in 76% of exposure notification recipients and were associated with a faster quarantine time in some SwissCovid user groups. The second  describes the public perception and current state of adoption of SwissCovid in Switzerland in light of prevalent misconceptions and overemphasised expectations. the third  places the evidence on SwissCovid in an international context. Specifically, we compare key performance indicators of SwissCovid, which are of similar magnitude as for digital proximity tracing apps from other European countries. Using findings from Switzerland, we subsequently derive a preliminary measure of the population-level effectiveness of digital proximity tracing apps. We estimate that exposure notifications may have contributed to the notification and identification of 500 to 1000 SARS-CoV-2-positive app users per month. We explore why this effectiveness estimation is somewhat lower when compared with Germany or the United Kingdom.

In light of the presented evidence, we conclude that digital proximity tracing works well in specific contexts, such as in mitigating non-household spread. However, future applications of digital proximity tracing should invest into stakeholder onboarding and increased process automatization – without deviating from the principles of voluntariness and user privacy.


  1. von Wyl V, Bonhoeffer S, Bugnion E, Puhan MA, Salathé M, Stadler T, et al. A research agenda for digital proximity tracing apps. Swiss Med Wkly. 2020 Jul;150(2930):w20324.
  2. COVID-19 Social Monitor. Accessed 2021 June 15.
  3. Corona Immunitas. Accessed 2021 June 15.
  4. Zurich Coronavirus Cohort : an observational study to determine long-term clinical outcomes and immune responses after coronavirus infection (COVID-19), assess the influence of virus genetics, and examine the spread of the coronavirus in the population of the Canton of Zurich, Switzerland. doi:
  5. Ballouz T, Menges D, Aschmann HE, Domenghino A, Fehr JS, Puhan MA, et al. Adherence and association of digital proximity tracing app notifications with earlier time to quarantine: results from the Zurich SARS-CoV-2 Cohort Study. Int J Public Health. 2021 Aug;66:1603992.
  6. Use of Venn Diagrams to Evaluate Digital Contact Tracing: Results from a Panel Survey Analysis. JMIR Preprints. Accessed 2021 June 15.
  7. Menges D, Aschmann HE, Moser A, Althaus CL, von Wyl V. A Data-Driven Simulation of the Exposure Notification Cascade for Digital Contact Tracing of SARS-CoV-2 in Zurich, Switzerland. JAMA Netw Open. 2021 Apr;4(4):e218184.
  8. Coronavirus: simplified, faster generation of SwissCovid app codes. Accessed 2021 June 15.
  9. Bundesamt für Statistik (BFS). Accessed 2021 June 15.
  10. Amann J, Sleigh J, Vayena E. Digital contact-tracing during the Covid-19 pandemic: an analysis of newspaper coverage in Germany, Austria, and Switzerland. PLoS One. 2021 Feb;16(2):e0246524.
  11. von Wyl V. Challenges for Nontechnical Implementation of Digital Proximity Tracing During the COVID-19 Pandemic: Media Analysis of the SwissCovid App. JMIR Mhealth Uhealth. 2021 Feb;9(2):e25345.
  12. Bundesamt für Statistik (BFS). SwissCovid-App-Monitoring. Accessed 2021 June 15.
  13. von Wyl V, Höglinger M, Sieber C, Kaufmann M, Moser A, Serra-Burriel M, et al. Drivers of Acceptance of COVID-19 Proximity Tracing Apps in Switzerland: Panel Survey Analysis. JMIR Public Health Surveill. 2021 Jan;7(1):e25701.
  14. Miller C. Apple releases iOS 12.5 for older iPhones with support for COVID-19 exposure notifications. 9to5Mac. Accessed 2021 June 15.
  15. Geber S, Friemel T. A Typology-Based Approach to Tracing-App Adoption During the COVID-19 Pandemic: The Case of the SwissCovid App. J Quant Descr Digit Media. 2021;1:
  16. Ferretti L, Wymant C, Kendall M, Zhao L, Nurtay A, Abeler-Dörner L, et al. Quantifying SARS-CoV-2 transmission suggests epidemic control with digital contact tracing. Science. 2020 May;368(6491):eabb6936.
  17. Salathé M, Althaus C, Anderegg N, Antonioli D, Ballouz T, Bugnon E, et al. Early evidence of effectiveness of digital contact tracing for SARS-CoV-2 in Switzerland. Swiss Med Wkly. 2020 Dec;150(5153):w20457.
  18. Wymant C, Ferretti L, Tsallis D, Charalambides M, Abeler-Dörner L, Bonsall D, et al. The epidemiological impact of the NHS COVID-19 app. Nature. 2021 Jun;594(7863):408–12.
  19. Robert Koch Institut (RKI). Accessed 2021 June 15.
  20. Factsheet CoronaMelder. Accessed 2021 June 15.
  21. NHS COVID-19 app statistics. Accessed 2021 June 15. downloads
  22. The Covid Tracing Tracker. What’s happening in coronavirus apps around the world. MIT Technology Review. Accessed June 15, 2021.
  23. online heise. RKI-Schätzung: Corona-Warn-App hat über 100.000 Infektionsketten unterbrochen. Accessed 2021 June 15.
  24. Swiss Admin. Accessed June 15, 2021.
  25. Levine-Tiefenbrun M, Yelin I, Katz R, Herzel E, Golan Z, Schreiber L, et al. Initial report of decreased SARS-CoV-2 viral load after inoculation with the BNT162b2 vaccine. Nat Med. 2021 May;27(5):790–2. 01316-7

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