World Health Organization (WHO) Director-General Tedros Adhanom Ghebreyesus speaks at a daily briefing in Geneva, Switzerland, March 9, 2020. [Photo/Xinhua]

Firefighters prepare to conduct disinfection in a middle school in Wuhan, central China's Hubei Province, April 22, 2020. [Photo/Xinhua]

A medical worker prepares to receive the first batch of COVID-19 patients at Leishenshan Hospital in Wuhan, capital of central China's Hubei Province, Feb. 8, 2020. [Photo/Xinhua]

Medical workers carry a patient from an ambulance to George Washington University Hospital in Washington D.C., the United States, on April 27, 2020. [Photo/Xinhua]