AUTHOR=Meijerink Hinta , Mauroy Camilla , Johansen Mia Karoline , Braaten Sindre Møgster , Lunde Christine Ursin Steen , Arnesen Trude Margrete , Feruglio Siri Laura , Nygård Karin , Madslien Elisabeth Henie 

TITLE=The First GAEN-Based COVID-19 Contact Tracing App in Norway Identifies 80% of Close Contacts in “Real Life” Scenarios

JOURNAL=Frontiers in Digital Health

VOLUME=Volume 3 - 2021

YEAR=2021

URL=https://www.frontiersin.org/journals/digital-health/articles/10.3389/fdgth.2021.731098

DOI=10.3389/fdgth.2021.731098

ISSN=2673-253X

ABSTRACT=The COVID-19 response in most countries has relied on testing, isolation, contact tracing, and quarantine (TITQ), which is labor- and time consuming. Therefore, several countries worldwide launched Bluetooth based apps as supplementary tools. The aim of using contact tracing apps is to rapidly notify people about their possible exposure to SARS-CoV-2 and thus making the process of TITQ more efficient, especially upon exposures in public places. We evaluated the Norwegian GAEN- based contact tracing app Smittestopp v2 under relevant “real-life” test scenarios.
We used a total of 40 devices, representing six different brands, and compared two different exposure configurations, experimented with different time thresholds and weights of the Bluetooth attenuation levels (buckets) and calculated true notification rates among close contacts (≤2 meters and ≥15 mins) and false notification of sporadic contacts. In addition, we assessed the impact of using different operating systems and locations of the phone (hand/pocket).  
The best configuration tested to trigger exposure notification resulted in correct notification of 80% of the true close contacts and incorrect notification of 34% of the sporadic contacts. Among those who incorrectly received notifications, most (67%) were within 2 meters but duration of contact was less than 15 minutes and thus they were not, per se, considered as “close contacts”.  Lower sensitivity was observed when using the iOS operating systems or carrying the phone in the pocket instead of in the hand. 
The results of this study were used to improve and evaluate the performance of the Norwegian contact-tracing app Smittestopp.