A medical worker from the Affiliated Hospital of Qingdao University checks her face mask at Guanggu area of Wuhan-based Tongji Hospital in Wuhan, central China's Hubei Province, Feb. 20, 2020. To better protect medical workers, some targeted and precise prevention measures are strictly taken during work time and off-work time by medical staff of the Affiliated Hospital of Qingdao University who are in Hubei to aid the fight against the virus. (Xinhua/Cai Yang)