All HCoVs have a zoonotic origin. Whereas bats are the evolutionary reservoir host of 229E, NL63, SARS-CoV, MERS-CoV, and SARS-CoV-2, parental viruses of OC43 and HKU1 have been found in rodents. Intermediate and amplifying hosts of HCoVs were also found in domestic and wild mammals. Ancestors of OC43 were identified in domestic animals such as cattle and swine. The switch of hosts from cattle or pigs to humans might have occurred in the context of a pandemic of respiratory disease recorded around 1890 in human history [26]. Similar to MERS-CoV, 229E could be acquired by humans from dromedary camels. However, the direction of this cross-species transmission remains to be determined and the possibility cannot be excluded that both humans and camels might have acquired 229E from an unidentified host including bats [27].