bild

Covid-19 vaccine, illustration. Covid-19 is a respiratory disease caused by the SARS-CoV-2 coronavirus (previously 2019-nCoV). Coronaviruses cause respiratory tract infections in humans and are connected with common colds, pneumonia and SARS. SARS-CoV-2 is a particularly virulent strain that originated in Wuhan, China in late 2019. Covid-19 can develop into pneumonia and be fatal in some cases. (KEYSTONE/SCIENCE PHOTO LIBRARY/CLAUS LUNAU/SCIENCE PHOTO LIBRARY)