On February 21, the Central Epidemic Command Center (CECC) explained details about Case #939, an imported case of COVID-19 announced on February 17. Case #939 was confirmed to have COVID-19 in the United States in 2020. The case was given two tests, and both of her tests came back negative in the United States. After returning to Taiwan, she tested positive for COVID-19 (identified as the index case). The CECC held an expert advisory meeting on February 20 and adopted the following resolutions regarding the principles for identifying contacts of such cases:
1. Contacts of an index case are placed under home isolation, while the index case's condition and infectivity would be assessed;
2. When contacts are under home isolation, if the index case has met the criteria for leaving isolation and been released from isolation, and if the index case is assessed to have not been infectious when he or she came into contact with contacts, his or her contacts may also be released from home isolation, but they are still subjected to a 14-day self-health management.