A medical service team check a record of workers' body temperature at the base of auto maker SGMW in Qingdao, east China's Shandong Province, Feb. 17, 2020. To ensure the normal production of enterprises after resuming work, Xihai'an (West Coast) New Area of Qingdao has set up medical service teams to serve enterprises. The first batch of 279 medical personnel of 50 medical service teams were stationed in key enterprises to assist in the epidemic prevention and control. (Xinhua/Li Ziheng)

Authorities in East China's coastal city Qingdao sealed off some blocks of local residential compounds and hospitals after three asymptomatic COVID-19 patients were found on Sunday.

A preliminary and epidemiological investigation showed that the cases were all related to the Qingdao Chest Hospital, which has been receiving COVID-19 patients from overseas, according to the health authority of Qingdao. The source of infection is under investigation.

The city's anti-epidemic group immediately activated the emergency response by locking down the residential compounds where those patients live, as well as the Qingdao Chest Hospital and emergency department of Qingdao Central Hospital where the patients had been treated. Close contacts will be given nucleic acid tests and closely monitored.

All related environments have undergone disinfection. 

One of the patients is a 58-year-old man surnamed Han, who had been to Qingdao Central Hospital and had intended to be hospitalized in Qingdao Chest Hospital for phthisis. The other two were a nurse working at Qingdao Chest Hospital and her husband, who is a driver. 

On September 24, Qingdao reported two asymptomatic cases in a routine test of workers involved in cold chain production.

Global Times