The sixth transmission case originating in Korea involved Patient #25, a 73-year-old woman who tested positive at a screening clinic. Later, her son (Patient #26) and daughter-in-law (Patient #27) tested positive during the process of epidemiological investigation. After patients #26 and #27 entered Korea on January 31st from Zhuhai, Guangdong Province of China, via Macau, the 3 patients remained in the same place of residence in Korea. Considering that Patient #27 developed symptoms on February 4th, earlier than Patients #25 and #26, and Patient #25 did not have any previous history of overseas travel, it is likely that Patients #25 and #26 were infected by Patient #27.