Coronaviruses (CoV) are a large family of viruses that can cause illness ranging from the common cold to a more severe disease such as Middle East Respiratory Syndrome (MERS-CoV) and Severe Acute Respiratory Syndrome (SARS-CoV). Coronaviruses are zoonotic, meaning they are transmitted between animals and people. Detailed investigations found that SARS-CoV was transmitted from civet cats to humans and MERS-CoV from dromedary camels to humans. Several known coronaviruses are circulating in animals that have not yet infected humans.
Novel (meaning new) coronavirus (nCoV) is a new strain that had not been previously identified in humans. On 31 December 2019, WHO was informed of cases of pneumonia of unknown etiology (unknown cause) detected in Wuhan City, Hubei Province of China. A novel coronavirus (2019-nCoV) was identified as the causative virus by Chinese authorities on 7 January. Available evidence on the 2019-nCoV virus and previous experience with other coronaviruses (MERS-CoV and SARS-CoV) and other respiratory viruses (e.g., avian influenza) suggest that there may be zoonotic transmission associated with the 2019-nCoV.