Passengers undergo thermal scanning upon arrival at Incheon International Airport in Incheon, South Korea, Jan. 9, 2020. (Photos: Xinhua)

A staff member checks passengers' body temperature at Tan Son Nhat International Airport in south Vietnam's Ho Chi Minh City, Jan. 23, 2020.

Passengers undergo thermal scanning upon arrival at Singapore Changi Airport in Singapore, Jan 22, 2020.

A staff member looks at a computer monitor to check passengers' body temperature through a thermal scanner upon their arrival at Kualanamu International Airport in North Sumatra, Indonesia, Jan. 22, 2020.