Coloured transmission electron micrograph (TEM) of SARS-CoV-2 coronavirus particles (red) emerging from a cell cultured in a laboratory. SARS-CoV-2 (previously 2019-nCoV) was first identified in Wuhan, China, in December 2019. It is an enveloped RNA (ribonucleic acid) virus. The coronaviruses take their name from their crown (corona) of surface proteins, which are used to attach and penetrate their host cells. Covid-19 is a respiratory infection that can lead to fatal pneumonia. Image captured at Rocky Mountain Laboratories in Hamilton, Montana, USA.