Simula has published a scientific article about digital contact tracing based on anonymized data from the early period of digital contact tracing in Norway. The article demonstrates both the potential and some limitations of digital contact tracing. Digital contact tracing via mobile phones has been hailed, early into the pandemic, as a key tool to combat the spread of Covid-19. Countries around the world started developing such systems already in March 2020 and subsequently, a few countries started deploying such tools in April 2020. Realizing the enormous interest in digital contact tracing, the two tech giants Apple and Google collaborated to integrate digital contact tracing into their phones. This collaboration led to the launch of the so-called exposure notification system (ENS), which performs digital contact tracing in a privacy-preserving manner. As of today, around 50 countries have deployed a contact tracing app. The majority of apps in use are based on the ENS. Despite this enthusiasm, digital contact tracing has been marred by controversy over utility vs harm to privacy and a low adoption rate by the population. A major limitation is the lack of empirical evidence that shows whether digital contact tracing has delivered on its promise. This lack can be traced to the general lack of data on human contacts and the fact that the EN system shares no details about contacts with third parties in order to preserve privacy.
The published article aims to fill this gap by providing an empirical evaluation of a real-world deployment of digital contact tracing using millions of contact events. It used a unique anonymized and aggregated data set that was collected from the rollout of the first Norwegian contact tracing app, Smittestopp, in the Spring of 2020, which was developed pre-ENS and collected a detailed overview of contacts. The findings from the article support the emerging evidence that digital contact tracing is already contributing to slowing the pandemic. The article reports a high technological tracing efficacy of 80%, it also estimates that at least 11.0% of the discovered close contacts could not have been identified by manual contact tracing. Furthermore, the article shows that a contact tracing app with a modest to low uptake can play an important role in the current phase of the pandemic.
To the best of our knowledge, this work is the first to provide a detailed evaluation of a real deployment of digital contact tracing. Mounting evidence suggests that the strategy of Testing- Tracing-Isolation will remain crucial to contain this pandemic and future ones. Hence, the findings from this article can help inform public health policy on the integration of digital contact tracing into their toolbox in months and years to come.
Access the article:
Elmokashfi, A., Sundnes, J., Kvalbein, A. et al. Nationwide rollout reveals efficacy of epidemic control through digital contact tracing. Nat Commun 12, 5918 (2021). https://doi.org/10.1038/s41467-021-26144-8