On December 31, 2019, the Chinese government officially announced that the country had a single pneumonia case with an unknown cause. In the weeks after, South Korea had 24 confirmed cases by February 8, and the number has increased steadily since then. The highly contagious virus known as coronavirus disease 2019 (COVID-19) infected Case No. 31 in Daegu; she was the first patient related to Sincheonji Church. Later, the number of cases involved with Sincheonji skyrocketed. On March 6, 2020, the number of confirmed cases was 6284, with 42 dead. This study, through collecting epidemiological data about various COVID-19 infection cases, discovered that getting together in large groups leads to mass infection, and that paying close attention to personal hygiene by means of wearing masks, sanitary gloves, etc., can prevent the spread of COVID-19. Additional epidemiological data and related studies on COVID-19 infections in South Korea are likely to support or slightly modify this conclusion. However, this study is significant in that it emphasizes the precautionary principle in preventing and managing infectious diseases, and has a suggestion for public health policies, which are currently in high demand.