On Jan 10, WHO warned against airborne transmission in a medical setting
Archived: WHO Timeline - COVID-19
10 January 2020
WHO issued a comprehensive package of technical guidance online with advice to all countries on how to detect, test and manage potential cases, based on what was known about the virus at the time. This guidance was shared with WHO's regional emergency directors to share with WHO representatives in countries.
Based on experience with SARS and MERS and known modes of transmission of respiratory viruses, infection and prevention control guidance were published to protect health workers recommending droplet and contact precautions when caring for patients, and airborne precautions for aerosol generating procedures conducted by health workers.
12 January 2020
China publicly shared the genetic sequence of COVID-19.
https://www.who.int/news-room/detail/27-04-2020-who-timeline---covid-19
If it can be airborne in one setting, it can be airborne in others.
