Covid-19 coronavirus sample. Coloured transmission electron micrograph (TEM) of SARS-CoV-2 coronavirus particles (red) isolated from a patient with the disease Covid-19. 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. As of March 2020, the virus has spread to many countries worldwide. Around 90,000 have been infected with several thousand deaths. Travel restrictions and infection control measures have been put in place to slow the spread of the virus. This sample was imaged at the NIAID (National Institute of Allergy and Infectious Diseases) Integrated Research Facility (IRF) in Fort Detrick, Maryland, USA.