Arriving passengers wait in line at Qingdao Liuting International Airport in Qingdao, East China's Shandong province, March 5, 2020. The city has strengthened measures at its ports of entry to prevent and control imported COVID-19 cases from overseas. [Photo by Li Ziheng/Xinhua]

Staff members assists a passenger with his arrival card at Qingdao Liuting International Airport in Qingdao, East China's Shandong province, March 5, 2020. The city has strengthened measures at its ports of entry to prevent and control imported COVID-19 cases from overseas. [Photo by Li Ziheng/Xinhua]

Arriving passengers queue up to have body temperatures checked at Qingdao Liuting International Airport in Qingdao, East China's Shandong province, March 5, 2020. The city has strengthened measures at its ports of entry to prevent and control imported COVID-19 cases from overseas. [Photo by Li Ziheng/Xinhua]