Fig 1.

Coronavirus disease 19 outbreak curve and timeline of implementation of government interventions in South Korea. Note: This histogram is based on daily briefing reports from Korea Centers for Disease Control and Prevention. The report format of case numbers and related information has been changed several times depending on the situation. For example, specific information from travelers abroad became available from March 22 and is partially reflected in the histogram. (A) Expansion of suspected case definition from pneumonia or pneumonia-suspected symptoms after Wuhan visit within 14 days, to fever or respiratory symptoms after Hubei Province visit within 14 days. Expansion of patient under investigation definition from fever or respiratory symptoms after Wuhan visit within 14 days, to pneumonia after China visit within 14 days; (B) Changed the national infectious disease crisis level from “Alert” to “Warning,” started operating the COVID 19 Emergency Headquarters; (C) Started operating 288 selective care centers and screening all number of Wuhan tourists; (D) Expanded Korean Centers for Disease Control and Prevention call center (Tel: 1339) operation; (E) Started use of real time RT-PCR test kit at the 18 locations of Research Institutes of Public Health and Environment nationwide; (F) Changed contact definition from close contact and general contact to contact within 2 meters and 1:1 assignment of a public officer to the home self-contained people; (G) Isolated the COVID-19 Korean virus (BetaCoV/Korea/CDCD03/2020) and the Korean Ministry of Food and Drug Safety recommended use of KF94 and KF99 masks for healthcare personnel; (H) Expansion of case definition to fever of respiratory symptom within 14 days or physician's opinions; (I) Authorized emergency use of COVID-19 real-time RT-PCR test kits and expanded test centers to 46 private health care facilities; (J) Raised the national infectious disease crisis level from “Warning” to “Serious,” and declared the infectious disease special management zone with Daegu and Gyeongsangbuk-do; (K) Switched from the early detection and containment strategy to one of minimizing damage strategy, and provided updated response guidelines (7th edition); (L) Started mandatory reporting of symptoms at each facility with a designated staff; (M) Started an exit quarantine for travelers to the US and expanded a special entry procedure to travelers from Europe including mobile application report of self-monitoring of COVID-19 related symptoms; (N) Expanded the Special Entry Procedure to travelers from all countries; O) Started COVID-19 tests for all travelers from Europe and 15 days of “enhanced social distancing” until April 5; (P) Started COVID-19 tests for symptomatic travelers from USA; (Q) All travelers from abroad must self-isolate at home for 14 days and report daily symptoms using a self-isolation diagnostic application for smartphones; (R) Expanded the epidemiologic investigation scope of contact individuals from 1 day prior starting symptoms to 2 days prior; (S) Extended “enhanced social distancing” for 2 weeks more until April 19, and started legal enforcement in which violations of self-containment may result in imprisonment of not more than 1 year or a find not exceeding 10 million Korean won (ie, $8,250).