  On June 16, 2020, Germany launched an open-source smartphone contact tracing
app ("Corona-Warn-App") to help tracing SARS-CoV-2 (coronavirus) infection
chains. It uses a decentralized, privacy-preserving design based on the
Exposure Notification APIs in which a centralized server is only used to
distribute a list of keys of SARS-CoV-2 infected users that is fetched by the
app once per day. Its success, however, depends on its adoption. In this
poster, we characterize the early adoption of the app using Netflow traces
captured directly at its hosting infrastructure. We show that the app generated
traffic from allover Germany---already on the first day. We further observe
that local COVID-19 outbreaks do not result in noticeable traffic increases.
