Coronaviruses are a large family of viruses, some of which cause illness in people, and others that circulate among mammals and birds. Rarely, animal coronaviruses can spread to humans, and then spread between people. Zoonotic coronaviruses have emerged in recent years to cause human outbreaks such as coronavirus disease 2019 (COVID-19), severe acute respiratory syndrome (SARS), and Middle East respiratory syndrome (MERS).
Illness in humans mainly manifests as a respiratory infection, or sometimes gastrointestinal infection. The clinical spectrum of illness varies from no symptoms or mild respiratory symptoms to severe, rapidly progressive pneumonia, acute respiratory distress syndrome, septic shock, or multiorgan failure resulting in death.
