2. How are coronavirus and animal related?

Many viruses that infect humans are originally viruses carried by animals. When the viruses in animals mutate, they may come to infect humans, replicate in human body and spread among people. Animal coronaviruses primarily comprise mammalian coronaviruses and avian coronaviruses. Mammalian coronaviruses are mostly α and β coronaviruses, which infect dogs, cats, mice, pigs, cattle, horses, bats and other animals. Avian coronaviruses are mainly derived from γ and δ genus coronaviruses and can infect birds such as chickens, ducks, geese, pigeons and sparrows.