Background: The transmission mode of severe acute respiratory syndrome coronavirus 2 is primarily known as droplet transmission. However, a recent argument has emerged about the possibility of airborne transmission. On June 17, there was a coronavirus disease 2019 (COVID-19) outbreak in Korea associated with long distance droplet transmission. Methods: The epidemiological investigation was implemented based on personal interviews and data collection on closed-circuit television images, and cell phone location data. The epidemic investigation support system developed by the Korea Disease Control and Prevention Agency was used for contact tracing. At the restaurant considered the site of exposure, air flow direction and velocity, distances between cases, and movement of visitors were investigated. Results: A total of 3 cases were identified in this outbreak, and maximum air flow velocity of 1.2 m/s was measured between the infector and infectee in a restaurant equipped with ceiling-type air conditioners. The index case was infected at a 6.5 m away from the infector and 5 minutes exposure without any direct or indirect contact. Conclusion: Droplet transmission can occur at a distance greater than 2 m if there is direct air flow from an infected person. Therefore, updated guidelines involving prevention, contact tracing, and quarantine for COVID-19 are required for control of this highly contagious disease.

The authors regret that there was an important error in the methods section. The genome sequencing preparation section in methods was not approved to publish by the original researchers. The 4 sentences ("In total, … were generated.") related with genome sequencing preparation in 'Personal factor investigation' section should be removed. Content of corrections:1. The contents of the last 4 sentences were removed in the 'Personal factor investigation section' of METHODS. 2. The reference number 8 is used as a reference of the previous sentence of removed contents. Before METHODS Personal factor investigationThe epidemiological investigation was implemented according to the 'Infectious Diseases Control and Prevention Act' (Act number 16725) in Korea and the guidelines for response to COVID-19 by the Korea Disease Control and Prevention Agency (KDCA). 4 Data comprising patient's personal statements by interview, medical institution usage history, credit card record, closed-circuit television (CCTV) images, cell phone location data, and other associated information were secured by an epidemiological investigation team. 5 The Epidemic Investigation Support System (EISS) developed by KDCA was also used for location tracking of confirmed cases and hot-spot analysis. 6 Nasopharyngeal specimens of cases and close contacts were collected and tested using real-time reverse transcription polymerase chain reaction (rRT-PCR) by Jeollabuk-do Institute of Health & Environment Research, and genome sequencing analysis for verifying association between cases was performed by the KDCA. 7 In total, 10-100 ng of the extracted viral RNA with a maximum volume of 8.5 µL was