Coronaviruses are a group of viruses that cause diseases in mammals and birds. In humans, coronaviruses cause respiratory tract infections that are typically mild, such as the common cold, though rarer forms such as SARS, MERS and COVID-19 can be lethal. Symptoms vary in other species: in chickens, they cause an upper respiratory tract disease, while in cows and pigs they cause diarrhea. There are yet to be vaccines or antiviral drugs to prevent or treat human coronavirus infections.

Coronavirus disease 2019 (COVID-19) is an infectious disease caused by SARS-CoV-2, a virus closely related to the SARS virus. The disease is the cause of the 2019–20 coronavirus outbreak. It passes from one person to others via respiratory droplets produced from the airways, often during coughing or sneezing. Time from exposure to onset of symptoms is generally between 2 and 14 days. Hand washing, maintaining distance from people who are coughing, and not touching one’s face are recommended to prevent the disease. It is recommended to cover one’s nose and mouth with a bent elbow when coughing.

People may have few symptoms or develop fever, cough, and shortness of breath. Cases can progress to pneumonia and multi-organ failure. There is no vaccine or specific antiviral treatment, with management involving treatment of symptoms, supportive care, and experimental measures. The case fatality rate is estimated at between 1% and 3%.