The Characteristics of Middle Eastern Respiratory Syndrome Coronavirus Transmission Dynamics in South Korea

Kim, Yunhwan; Lee, Sunmi; Chu, Chaeshin; Choe, Seoyun; Hong, Saeme; Shin, Youngseo

The earliest two confirmed cases were the primary case (68-year-old man) and his wife. The ongoing outbreak in South Korea began when the primary case developed respiratory illness on May 11, 2015 after returning on May 4, 2015 from the Middle East (April 24 th eMay 4 th ). Further epidemiological investigation showed that the primary case had also traveled to the Barain, United Arab Emirates, Saudi Arabia, and Qatar. The first symptom, which included fever, muscle aches, cough, and dyspnea, was detected on May 11 th , 2015. On May 20 th , 2015, he was diagnosed with MERS-CoV, so the patient was isolated and treated in hospital designated by the Korea government. After that, MERS-CoV spread in South Korea from the man, and we currently have 186 confirmed cases including 36 death cases (July 7, 2015). Table A1 shows three kinds of characteristics of confirmed cases; age group, sex, and occupation. In occupation, infected patients are classified into three groups; Health Workers, Epidemiologic Survey, and Visitor/Family. We can derive the mortality rates by occupation from the numbers in the table, which are 2.6% in health workers, 25.6% in Epidemiologic Survey, and 17% in Visitor/Family, and we can see that the mortality rate is the highest in Epidemiologic Survey. Figure A1 presents the time, the location, and the number of infections by the primary patient until he was isolated, and Table A2 displays the number of infected cases by the hospitals that the primary patient had visited before isolation. As the table shows, while it was Pyeongtaek St. Mary's Hospital where the primary case was confirmed, Samsung Medical Center was the location where the largest number of people were infected. It also draws attention that the number of cases decreases by the order of infection in Pyeongtaek St. Mary's Hospital while it tends to increase in Samsung Medical Center. Figure A2 illustrates a transmission tree that MERS-CoV spread from primary case to 153 cases on June 15, 2015. The number of first-order infected cases is 39, that of second-order infected cases is 104, and that of thirdorder infected cases is seven. We omit some patients in Figure A2 rb g a þ g I þ rg a bl g r ðg a þ g I Þ b g a þ g I þ g a bl g r ðg a þ g I Þ South Korea is largely attributed to these superspreaders.