Patient age was provided on the date of diagnosis, and key indicators such as estimated duration of exposure, date of onset of symptoms, and route of transmission were identified by an epidemiological investigator who participated in the field investigation and the epidemiological investigation team at KCDC headquarters. The incubation period was estimated based on the estimated exposure date and the date of symptom onset. However, it must be noted that the data presented in this study may change depending on the results of further epidemiological investigation.