Combo photo taken on March 20, 2020 shows Yang Liqiong, a medical worker from northwest China's Ningxia Hui Autonomous Region, wearing a face mask (L) and her smiling face after taking off the mask before her departure in Xiangyang City, central China's Hubei Province. Medical staff supporting virus-hit Hubei Province have started to depart the province as the epidemic situation has been greatly eased. (Xinhua/Xie Jianfei)

Combo photo taken on March 20, 2020 shows Zou Lili, a medical worker from northwest China's Ningxia Hui Autonomous Region, wearing a face mask (L) and her smiling face after taking off the mask before her departure in Xiangyang City, central China's Hubei Province. Medical staff supporting virus-hit Hubei Province have started to depart the province as the epidemic situation has been greatly eased. (Xinhua/Xie Jianfei)

Combo photo taken on March 21, 2020 shows Wang Lili, a medical worker from northeast China's Liaoning Province, wearing a face mask (L) and her smiling face after taking off the mask before her departure in Xiangyang City, central China's Hubei Province. Medical staff supporting virus-hit Hubei Province have started to depart the province as the epidemic situation has been greatly eased. (Xinhua/Xie Jianfei)

Combo photo taken on March 20, 2020 shows Zhang Zhihong, a medical worker from northwest China's Ningxia Hui Autonomous Region, wearing a face mask (L) and her smiling face after taking off the mask before her departure in Xiangyang City, central China's Hubei Province. Medical staff supporting virus-hit Hubei Province have started to depart the province as the epidemic situation has been greatly eased. (Xinhua/Xie Jianfei)

Combo photo taken on March 20, 2020 shows Wang Hong, a medical worker from northwest China's Ningxia Hui Autonomous Region, wearing a face mask (L) and her smiling face after taking off the mask before her departure in Xiangyang City, central China's Hubei Province. Medical staff supporting virus-hit Hubei Province have started to depart the province as the epidemic situation has been greatly eased. (Xinhua/Xie Jianfei)

Combo photo taken on March 20, 2020 shows Li Qiang, a medical worker from northwest China's Ningxia Hui Autonomous Region, wearing a face mask (L) and his smiling face after taking off the mask before his departure in Xiangyang City, central China's Hubei Province. Medical staff supporting virus-hit Hubei Province have started to depart the province as the epidemic situation has been greatly eased. (Xinhua/Xie Jianfei)

Combo photo taken on March 21, 2020 shows Zhou Jiamin, a medical worker from northeast China's Liaoning Province, wearing a face mask (L) and her smiling face after taking off the mask before her departure in Xiangyang City, central China's Hubei Province. Medical staff supporting virus-hit Hubei Province have started to depart the province as the epidemic situation has been greatly eased. (Xinhua/Xie Jianfei)

Combo photo taken on March 20, 2020 shows Li Ting, a medical worker from northwest China's Ningxia Hui Autonomous Region, wearing a face mask (L) and her smiling face after taking off the mask before her departure in Xiangyang City, central China's Hubei Province. Medical staff supporting virus-hit Hubei Province have started to depart the province as the epidemic situation has been greatly eased. (Xinhua/Xie Jianfei)