See: What causes coronavirus?

Coronaviruses (CoV) are a large family of viruses that cause
illness ranging from the common cold to more severe
diseases such as Middle East Respiratory Syndrome (MERS-
CoV) and Severe Acute Respiratory Syndrome (SARS-CoV) .
A novel coronavirus (nCoV) is a new strain that has not been
previously identified in humans.
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.
Common signs of infection include respiratory symptoms,
fever, cough, shortness of breath and breathing difficulties.
In more severe cases, infection can cause pneumonia, severe
acute respiratory syndrome, kidney failure and even death.
Standard recommendations to prevent infection spread
include regular hand washing, covering mouth and nose
when coughing and sneezing, thoroughly cooking meat and
eggs. Avoid close contact with anyone showing symptoms
of respiratory illness such as coughing and sneezing.