The CDC released an interesting analysis of a case study of a COVID-19 outbreak among 10 people from three families whose only common denominator was that they all ate at the same air-conditioned restaurant on January 23, 2020, in Guangzhou, China. Spoiler alert: It wasn’t the food.
Family A, who had just been in Wuhan, and Families B and C all sat at neighboring tables for their meal for an overlapping period of more that 50 minutes. Later that day, a member of Family A began experiencing symptoms of fever and cough.
The air outlet and return air inlet for the central air conditioning were located above Family C’s table. Given that COVID-19 is commonly transmitted through droplets, the CDC concluded the most likely scenario was that three of Family B’s members were infected and two of Family C’s were infected by the Family A member by strong airflow from the air conditioner that could have propagated droplets from table C to table A, then to table B, and then back to table C.
In light of this scenario, CDC recommends strengthening temperature-monitoring surveillance, increasing the distance between tables, and improving ventilation. You can read the full report here: https://wwwnc.cdc.gov/eid/article/26/7/20-0764_article