METHODS: In mid-January 2020, a Chinese family made a visit to a local city, and within the next 2 wk one after another fell ill with COVID-19. At the beginning of their first illness onset, the family had eaten in a restaurant, which led to the subsequent illness onset in another two families. All cases were diagnosed as COVID-19 by real-time fluorescent reverse transcription-polymerase chain reaction. Epidemiological investigation showed that the transmission chain was complete.
CONCLUSIONS: This chain of social exposure highlights the danger of group aggregative behavior for spread of COVID-19.