It's from an article in CDC Emerging Infectious Diseases by a group in Guangzhou CDC (China). People occupying the seats circled in red came down with Covid-19 and became symptomatic on the date shown.
But this is misleading. As the article actually says:
On January 23, 2020, family A traveled from Wuhan and arrived in Guangzhou. On January 24, the index case-patient (patient A1) ate lunch with 3 other family members (A2–A4) at restaurant X. Two other families, B and C, sat at neighboring tables at the same restaurant. Later that day, patient A1 experienced onset of fever and cough and went to the hospital.So, one family per table. Family A traveled to Wuhan together., and patient A1 will be hospitalized within a few hours.
From the dates I would guess that B1 was infected by A1 and the other B's could easily have been infected by B1. C2 became symptomatic only 3 days later. That is very fast but not impossible. Median incubation period is 5 days. Another possibility would be independent infections, but there weren't a lot of cases in Guangzhou yet on this date. C2 likely infected C3.
There are no other known exposures for family B or C. So, 2 transmissions (not 9).
Also both B1 and C1 were seated a little further away from A1 than you would guess that droplets will go.
