COVID-19: cross-border contact tracing in Germany, February to April 2020

Introduction: The Robert Koch Institute (RKI) managed the exchange of cross-border contact tracing data between public health authorities (PHA) in Germany and abroad during the early COVID-19 pandemic. Aim: We describe the extent of cross-border contact tracing and its challenges. Methods: We analysed cross-border COVID-19 contact tracing events from 3 February to 5 April 2020 using information exchanged through the European Early Warning Response System and communication with International Health Regulation national focal points. We described events by PHA, number of contacts and exposure context. Results: The RKI processed 467 events, initiating contact to PHA 1,099 times (median = 1; interquartile range (IQR): 1-2) and sharing data on 5,099 contact persons. Of 327 (70%) events with known exposure context, the most commonly reported exposures were aircraft (n = 64; 20%), cruise ships (n = 24; 7%) and non-transport contexts (n = 210; 64%). Cruise ship and aircraft exposures generated more contacts with authorities (median = 10; IQR: 2-16, median = 4; IQR: 2-11) and more contact persons (median = 60; IQR: 9-269, median = 2; IQR: 1-3) than non-transport exposures (median = 1; IQR: 1-6 and median = 1; IQR: 1-2). The median time spent on contact tracing was highest for cruise ships: 5 days (IQR: 3-9). Conclusion: In the COVID-19 pandemic, cross-border contact tracing is considered a critical component of the outbreak response. While only a minority of international contact tracing activities were related to exposure events in transport, they contributed substantially to the workload. The numerous communications highlight the need for fast and efficient global outbreak communication channels between PHA.