Currently, the COVID-19 cases originating in Korea have been reported to be index cases imported from abroad, and resultant first-generation and second-generation cases. So far, all the patients confirmed to have COVID-19 have identifiable epidemiological connections. In other words, cases of secondary infection were limited to closely related people (family and acquaintances) who spent time together co-dining and co-habiting. It is important to analyze and share such epidemiological and clinical data on COVID-19 to establish an effective response strategy.