Table 3.

Prevention policies in US during 2020-2021

Date	Policy in the US
2020/01/16	Entry screening for passengers traveling to the U.S. via direct or connecting flights from Wuhan, China
2020/01/30	U.S. citizens are reminded not to travel to mainland China
2020/02/11	Suspend flights to mainland China and Hong Kong
2020/03/14	Passing the Coronavirus Relief Program (Testing Free/Paid Leave/Unemployment Insurance/Medicaid)
2020/04/03	Ban on the export of medical supplies in short supply
2020/04/21	Ban immigration to the United States
2020/12/14	U.S. Severe Special Infectious Pneumonia Vaccination Program Officially Starts
2021/03/22	Require the public to wear masks for the next 100 days/compulsory quarantine upon entry from the airport/increase vaccine production
2021/05/19	From February 2 to March 3, the United States refused entry to 241 foreigners, including 14 repatriated at airports and 227 at land ports. In addition, 106 foreign nationals were denied entry during pre-clearance outside the U.S.