Just saw this pre-print “COVID-19 Outbreak Associated with Air Conditioning in Restaurant, Guangzhou, China, 2020“. Very short, very to the point. Evidence that droplet transmission happened in this particular outbreak via the ventilation within a building. Abstract below:
During January 26–February 10, 2020, an outbreak of 2019 novel coronavirus disease in an air-conditioned restaurant in Guangzhou, China, involved 3 family clusters. The airflow direction was consistent with droplet transmission. To prevent the spread of the virus in restaurants, we recommend increasing the distance between tables and improving ventilation.