The first confirmed case of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection in South Korea was imported from China on January 20, 2020. By February 10, there were 28 cases of laboratory-confirmed coronavirus 2019 (Covid-19, the illness caused by SARS-CoV-2 infection) in South Korea (Fig. S1 in the Supplementary Appendix, available with the full text of this letter at NEJM.org). The characteristics of these patients
1 and the patient numbers are provided in Table S1. The median age of the patients was 41 years (range, 21 to 73), and 15 of the 28 patients (54%) were men. The mean interval (±SD) from symptom onset to diagnosis was 4.3±4.1 days.