Answer: Coronaviruses are a large family of viruses that usually cause mild to moderate upper-respiratory tract illnesses, like the common cold.
Explanation: However, three new coronaviruses have been revealed from animal reservoirs over the past few years to cause large amounts of illness and death. There are hundreds of coronaviruses, most of which circulate among such animals that are smaller. Sometimes those viruses spread to humans which is called a spillover event and can cause disease.
And thats all i really know. :L