Photo taken on May 3, 2020 shows illuminated buildings at the Hongyadong scenic area in southwest China's Chongqing. Measures for COVID-19 prevention and control are still carried out in Chongqing's famous Hongyadong scenic area during the Labor Day holiday. Visitors are required to pre-book their tours and plan their visit ahead of time to avoid overcrowding. (Xinhua/Wang Quanchao)

Tourists enter the Hongyadong scenic area in southwest China's Chongqing, May 3, 2020. Measures for COVID-19 prevention and control are still carried out in Chongqing's famous Hongyadong scenic area during the Labor Day holiday. Visitors are required to pre-book their tours and plan their visit ahead of time to avoid overcrowding. (Xinhua/Wang Quanchao)

Tourists enter the Hongyadong scenic area in southwest China's Chongqing, May 3, 2020. Measures for COVID-19 prevention and control are still carried out in Chongqing's famous Hongyadong scenic area during the Labor Day holiday. Visitors are required to pre-book their tours and plan their visit ahead of time to avoid overcrowding. (Xinhua/Wang Quanchao)

Tourists have their body temperature measured before entering the Hongyadong scenic area in southwest China's Chongqing, May 3, 2020. Measures for COVID-19 prevention and control are still carried out in Chongqing's famous Hongyadong scenic area during the Labor Day holiday. Visitors are required to pre-book their tours and plan their visit ahead of time to avoid overcrowding. (Xinhua/Wang Quanchao)