Investigation of a nosocomial outbreak of COVID-19 in a pediatric ward in South Korea: Successful control by early detection and extensive contact tracing with testing.

We describe an outbreak investigation related to a paucisymptomatic 9-year-old girl with COVID-19 admitted at a pediatric ward in a tertiary hospital (South Korea). The pediatric wards were placed under cohort isolation and an extensive contact-tracing was carried out. Of 1,206 close and casual contacts, a female asymptomatic guardian, who was the mother (secondary case) of an infant that shared the room with the index patient, was found positive. Thirteen days after the diagnosis, her asymptomatic 2-year-old daughter (tertiary case) who contacted her at home was found positive. Early detection of an asymptomatic case based on epidemiologic link followed by extensive contact-tracing and testing for SARS-CoV-2 appears to be important in effectively containing a nosocomial outbreak of COVID-19.