Investigation of a cluster of COVID-19 cases imported through inbound air flight

  Objective  To understand the epidemiological characteristics and explore source of infection of coronavirus disease 2019 (COVID-19) cases imported through an inbound air flight from Kenya to Guangzhou, China.

  Methods  Using a standardized questionnaire, we collected information of the travelers’ demographic characteristics and illness before, during, and after the flight. We also collected data about the factors potentially associated with COVID-19 transmission during the flight by retrospective cohort study.

  Results  There were 211 passengers and 14 crew members on the flight. A total of 31 COVID-19 patients were diagnosed among all passengers, in which 11 (35.48%) were symptomatic and 20 (64.52%) were asymptomatic. The attack rate was 14.69% (31/211). The cases were mainly the employees of GC Company. Retrospective cohort study suggested that high frequency of contact with foreigners or sharing rooms with COVID-19 cases in the Republic of Congo were risk factors for SARS-CoV-2 infection. The risk ratios were 6.250 for the passengers high frequency of contact with foreigners (95% CI: 1.095–35.682) and 11.500 for the passengers sharing rooms with COVID-19 cases (95% CI: 1.835–72.069) and.

  Conclusion  The cases detected in this flight might be infected outside China, and the possibility of being infected due to the exposure in the flight was low. But it is still necessary to take effective personal protection in airplanes.