Investigation of a COVID-19 Cluster in a State Quarantine Facility in Thailand and Prevention Measures for Incoming Travelers

Abstract

Coronavirus disease (COVID-19) became a global pandemic in 2020. Thailand introduced a mandatory 14-day quarantine at government facilities for all arrivals. On 15 May 2020, the Department of Disease Control received notification concerning ten confirmed COVID-19 cases at a state quarantine center. A joint investigation led by the Department of Disease Control confirmed the diagnoses, identified the source of infection, and assessed the state quarantine’s environment and procedures. The confirmed cases were all on a flight from Pakistan. The attack rate among the passengers was 9%. All had a risk history of COVID-19 infection in Pakistan, such as attending crowded areas and living in an area with a COVID-19 outbreak. On the flight, three possible clusters could be classified using the two-row rule; however, all cases wore a face mask throughout the journey. Transmission was unlikely to have occurred at the quarantine center due to a lack of contact history and appropriate preventive measures in place. This investigation provides insight into the state quarantine practices and shows gaps for improvement, such as using genomic data for cluster identification and developing a COVID-19 questionnaire for use at the quarantine center.