Nationwide rollout reveals efficacy of epidemic control through digital contact tracing (preprint)

Fueled by epidemiological studies of SARS-CoV-2, contact tracing by mobile phones has been put to use in many countries. A year into the pandemic, we lack conclusive evidence on its effectiveness. Here, we used a unique real world contact data set, collected during the rollout of the first Norwegian contact tracing app in the Spring of 2020, to address this gap. Our dataset involves millions of contacts between 12.5% of the adult population, and enabled us to measure the real-world app performance. The technological tracing efficacy was measured at 80%, and we estimated that at least 11.0% of the discovered close contacts could not be identified by manual contact tracing. The overall effectiveness of digital tracing depends strongly on app uptake, but significant impact can be achieved for moderate uptake numbers. Used as a supplement to manual tracing and other measures, digital tracing can be instrumental in controlling the pandemic. Our findings can thus help informing public health policies in the coming months.

A Multi-Perspective Study of Internet Performance during the COVID-19 Outbreak (preprint)

The rapid spread of the novel corona virus, SARS-CoV-2, has prompted an unprecedented response from governments across the world. A third of the world population have been placed in varying degrees of lockdown, and the Internet has become the primary medium for conducting most businesses and schooling activities. This paper aims to provide a multi-prospective account of Internet performance during the first wave of the pandemic. We investigate the performance of the Internet control plane and data plane from a number of globally spread vantage points. We also look closer at two case studies. First, we look at growth in video traffic during the pandemic, using traffic logs from a global video conferencing provider. Second, we leverage a country-wide deployment of measurement probes to assess the performance of mobile networks during the outbreak. We find that the lockdown has visibly impacted almost all aspects of Internet performance. Access networks have experienced an increase in peak and off-peak end to end latency. Mobile networks exhibit significant changes in download speed, while certain types of video traffic has increased by an order of magnitude. Despite these changes, the Internet seems to have coped reasonably well with the lockdown traffic.