Study involving IFISC highlights importance of COVID-19 tracking apps

April 29, 2021

Automating the process of identifying people who have had contact with a COVID-infected person is the main objective of smartphone applications that have emerged during the COVID-19 pandemic, such as TousAntiCovid in France or Radar Covid in Spain. 

An international team of scientists led by Pierre-Louis Institute of Epidemiology and Public Health, and with participation of PhD students from IFISC (UIB-CSIC), has published a study in Science Advances that aims to assess the impact of these app-based digital contact tracing in the COVID-19 epidemic in France. In order to do so, they proposed a compartmental model applied in a dynamical-multilayered network of individuals, calibrated using real demographic, contact and epidemiological data. 

They explored realistic levels of case detection, app adoption, population immunity, and transmissibility. Exploring different scenarios of transmissibility in their model, characterised by the reproductive ratio R, has suggested that under a slight reduction of the transmissibility respect to the first wave reproductive ratio, a 20% app adoption reduces peak incidence by 35%. The reduction in peak incidence can get up to 60% if 60% of the population uses the contact tracking app. 

By incorporating household isolations, the usual form of containment measures employed by most European countries this past year, the researchers observed how both measures target transmissions in different age groups and settings. The app registered mostly contacts with adults, and the tracked contacts were occurring predominantly in workplaces and in the community. Household isolation reduced transmission in all settings, with the smallest effect in workplaces. Digital contact tracing has instead a high effectiveness at work, in the community, and in transports. 

The study concludes that adopting digital contact tracing apps led to decrease in transmissions with age, even among the oldest age range where smartphones are less predominant. This indirect shielding effect of the digital tracing procedure became more evident when testing the model with no individuals above 75 years old being able to use the app as no significant increase in cases was observed. These results highlight the importance of a contact tracing strategy during pandemics such as COVID-19 and how the development of apps that do this automatically is an advantage in prevention campaigns. 


Moreno López, JA, Arregui García, B, Bentkowski, P (et al.) 2021). Anatomy of digital contact tracing: Role of age, transmission setting, adoption, and case detection. Science Advances, 7(15), eabd8750.


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