Passengers with face masks are seen in a bus in New York City, the United States, Aug. 2, 2021. (Xinhua/Wang Ying)

A waiter wearing a mask serves customers at a restaurant in Miami-Dade County, Florida, the United States, Aug. 6, 2021. (Photo by Monica McGivern/Xinhua)

People visit the Washington Monument in Washington, D.C., the United States, Aug. 6, 2021. (Xinhua/Liu Jie)

A man receives a COVID-19 test at a mobile testing site in Times Square, New York, the United States, July 20, 2021. (Xinhua/Wang Ying)

A medical worker prepares a dose of COVID-19 vaccine at the Universal Studios Hollywood in Los Angeles, California, the United States, June 18, 2021. (Photo by Zeng Hui/Xinhua)