COVID-19 cross-border case and contact tracing activities - experiences and lessons learnt, Germany, April-December 2020 oleh Ida Sperle, Uwe Koppe, Raskit Lachmann, Robert Vonderwolke, Nadine Püschel, Nadine Litzba, Paula Böhm, Janina Stauke, Annika Heck, Jonathan H.J. Baum, Luam Ghebreghiorghis, Gyde Steffen, Ute Rexroth, Maria an der Heiden, Timm Schneider, Inessa Markus