Caption

Covid-19 pandemic, conceptual illustration. The new coronavirus SARS-CoV-2 (previously 2019-CoV) emerged in Wuhan, China, in December 2019. The virus (red) causes a mild respiratory illness (Covid-19) that can develop into pneumonia and be fatal in some cases. The coronaviruses take their name from their crown (corona) of surface spike proteins (protrusions), which are used to attach and penetrate their host cells.