![Pirna, Germany. 07th Dec, 2020. A sign for the mask obligation is screwed on in a pedestrian zone in the old town. According to figures from the Robert Koch Institute (RKI), the Pirna, Germany. 07th Dec, 2020. A sign for the mask obligation is screwed on in a pedestrian zone in the old town. According to figures from the Robert Koch Institute (RKI), the](https://c8.alamy.com/comp/2DFY9NE/pirna-germany-07th-dec-2020-a-sign-for-the-mask-obligation-is-screwed-on-in-a-pedestrian-zone-in-the-old-town-according-to-figures-from-the-robert-koch-institute-rki-the-7-day-incidence-in-the-district-of-saxon-switzerland-eastern-ore-mountains-climbed-above-the-500-new-infections-per-100000-inhabitants-within-one-week-credit-robert-michaeldpa-zentralbilddpaalamy-live-news-2DFY9NE.jpg)
Pirna, Germany. 07th Dec, 2020. A sign for the mask obligation is screwed on in a pedestrian zone in the old town. According to figures from the Robert Koch Institute (RKI), the
![Robert Koch Lecture 2017 - Dissecting human antibody responses: useful, basic and surprising findings | Max-Planck-Institut für Infektionsbiologie Robert Koch Lecture 2017 - Dissecting human antibody responses: useful, basic and surprising findings | Max-Planck-Institut für Infektionsbiologie](https://www.mpiib-berlin.mpg.de/event_images/11312-1508416937.jpeg)
Robert Koch Lecture 2017 - Dissecting human antibody responses: useful, basic and surprising findings | Max-Planck-Institut für Infektionsbiologie
![Stamp: Robert Koch (1843-1910) bacteriologist (Switzerland) (Famous persons) Mi:CH 958,Sn:CH 538,Yt:CH 889,Sg:CH 822,AFA:CH 953,Z… | Stamp, Postage stamps, Thematic Stamp: Robert Koch (1843-1910) bacteriologist (Switzerland) (Famous persons) Mi:CH 958,Sn:CH 538,Yt:CH 889,Sg:CH 822,AFA:CH 953,Z… | Stamp, Postage stamps, Thematic](https://i.pinimg.com/474x/03/4a/2d/034a2d6e073fb53213ef39a7d8673bfe.jpg)