Coronaviruses are a large family of viruses, some causing illness in people and others circulating among animals including camels, cats and bats.
There are several known coronaviruses that infect people and usually only cause mild respiratory disease, such as the common cold. However, at least two previously identified coronaviruses have caused severe disease — severe acute respiratory syndrome coronavirus (SARS-CoV) and Middle East respiratory syndrome coronavirus (MERS-CoV). SARS-CoV and MERS-CoV have been ruled out as the cause of the current outbreak.
While originally thought to spread from animal to person, recently, there have been indications that person-to-person spread is occurring in China and affected countries.
The infectious period for this virus is unknown. Based on other coronaviruses, people infected with 2019-nCOV should be considered to be contagious from the day of fever onset until 10 days after fever ends, or until appropriate laboratory testing shows the patient is no longer contagious.
Coronaviruses typically have an incubation period of 2‒14 days after exposure. The specific incubation period for this coronavirus is unknown.