A nurse speaks to an interphone at an isolation ward in Ditan Hospital in Beijing, capital of China, June 19, 2020. Beijing reported 227 COVID-19 cases on June 11-20. (Xinhua/Peng Ziyang)

A nurse helps a colleague put on a protective suit outside the isolation wards at Ditan Hospital in Beijing, capital of China, June 19, 2020. Beijing reported 227 COVID-19 cases on June 11-20. (Xinhua/Peng Ziyang)

Nurses get meals for COVID-19 patients outside the isolation ward at Ditan Hospital in Beijing, capital of China, June 19, 2020. Beijing reported 227 COVID-19 cases on June 11-20. (Xinhua/Peng Ziyang)

A nurse (L) who came to support the fight against the COVID-19 epidemic learns to use the interphone with the help of a nurse of Ditan Hospital at the isolation ward of the hospital in Beijing, capital of China, June 19, 2020. Beijing reported 227 COVID-19 cases on June 11-20. (Xinhua/Peng Ziyang)

Nurses help a colleague put on a protective suit outside the isolation wards at Ditan Hospital in Beijing, capital of China, June 19, 2020. Beijing reported 227 COVID-19 cases on June 11-20. (Xinhua/Peng Ziyang)

A nurse gestures to communicate with a COVID-19 patient outside an isolation ward at Ditan Hospital in Beijing, capital of China, June 19, 2020. Beijing reported 227 COVID-19 cases on June 11-20. (Xinhua/Peng Ziyang)

A nurse thanks a colleague for bringing a cooling vest at an isolation ward in Ditan Hospital in Beijing, capital of China, June 19, 2020. Beijing reported 227 COVID-19 cases on June 11-20. (Xinhua/Peng Ziyang)

Nurses distribute medicines outside the isolation wards at Ditan Hospital in Beijing, capital of China, June 19, 2020. Beijing reported 227 COVID-19 cases on June 11-20. (Xinhua/Peng Ziyang)

A nurse treats a COVID-19 patient at an isolation ward in Ditan Hospital in Beijing, capital of China, June 19, 2020. Beijing reported 227 COVID-19 cases on June 11-20. (Xinhua/Peng Ziyang)

A staff member cleans the corridor outside the isolation wards at Ditan Hospital in Beijing, capital of China, June 19, 2020. Beijing reported 227 COVID-19 cases on June 11-20. (Xinhua/Peng Ziyang)

Nurses change shifts at the nurse station of the isolation zone at Ditan Hospital in Beijing, capital of China, June 19, 2020. Beijing reported 227 COVID-19 cases on June 11-20. (Xinhua/Peng Ziyang)

Nurses help a colleague (C) get prepared before she enters the isolation zone at Ditan Hospital in Beijing, capital of China, June 19, 2020. Beijing reported 227 COVID-19 cases on June 11-20. (Xinhua/Peng Ziyang)

A nurse inquires a COVID-19 patient about his condition at Ditan Hospital in Beijing, capital of China, June 19, 2020. Beijing reported 227 COVID-19 cases on June 11-20. (Xinhua/Peng Ziyang)

A nurse puts on a protective suit outside the isolation wards at Ditan Hospital in Beijing, capital of China, June 19, 2020. Beijing reported 227 COVID-19 cases on June 11-20. (Xinhua/Peng Ziyang)

A COVID-19 patient (L) prepares to enter the isolation zone of Ditan Hospital in Beijing, capital of China, June 19, 2020. Beijing reported 227 COVID-19 cases on June 11-20. (Xinhua/Peng Ziyang)