People tour the National Mall in Washington, D.C., the United States, July 31, 2020. The number of COVID-19 cases surpassed 4.5 million with over 152,000 deaths in the United States on Friday. (Photo by Ting Shen/Xinhua)

A man tours the National Mall in Washington, D.C., the United States, July 31, 2020. The number of COVID-19 cases surpassed 4.5 million with over 152,000 deaths in the United States on Friday. (Photo by Ting Shen/Xinhua)

People tour the National Mall in Washington, D.C., the United States, July 31, 2020. The number of COVID-19 cases surpassed 4.5 million with over 152,000 deaths in the United States on Friday. (Photo by Ting Shen/Xinhua)

People tour the National Mall in Washington, D.C., the United States, July 31, 2020. The number of COVID-19 cases surpassed 4.5 million with over 152,000 deaths in the United States on Friday. (Photo by Ting Shen/Xinhua)

People tour the National Mall in Washington, D.C., the United States, July 31, 2020. The number of COVID-19 cases surpassed 4.5 million with over 152,000 deaths in the United States on Friday. (Photo by Ting Shen/Xinhua)

People tour the National Mall in Washington, D.C., the United States, July 31, 2020. The number of COVID-19 cases surpassed 4.5 million with over 152,000 deaths in the United States on Friday. (Photo by Ting Shen/Xinhua)