Potential roles of social distancing in mitigating the spread of coronavirus disease 2019 (COVID-19) in South Korea

Sang Woo Park; Kaiyuan Sun; Cécile Viboud; Bryan T Grenfell; Jonathan Dushoff

Since its first appearance in Wuhan, China, in December 2019 [1] , coronavirus disease has spread internationally, including to South Korea. The first COVID-19 case in South Korea was confirmed on January 20, 2020, from a traveling resident of Wuhan, China [2] . In February, the disease spread rapidly within a church community in the city of Daegu [2] . The chains of transmission that began from this cluster distinguish the epidemic in South Korea from that in any other countries: As of March 24, 2020, 9,037 cases were confirmed, of which 56% were related to the church and 27% were in their 20s [2] . South Korea's intensive testing using novel contact tracing techniques allowed rapid identification and isolation cases and reduction of onward transmission [3, 4, 5] . Here, we describe potential roles of social distancing in mitigating the spread of COVID-19 in South Korea by using metro traffic data to compare epidemics in two major cities.