A hospital in east China designated for treating imported cases of Covid-19 has stopped accepting any new patients after three local people with links to the facility were confirmed as being asymptomatic cases. The Qingdao Chest Hospital in Shandong province has temporarily closed all of its departments and doctors are helping with an investigation, Health Times reported on Sunday. All of the cases had links to the hospital, the Qingdao Health Municipal Health Commission said. One of the three is a 58-year-old man with the surname Han who was treated for tuberculosis at the hospital last month, the report said. The second is a 53-year-old woman surnamed Jiang who worked at the hospital from July to September, and the third, surnamed Shao, is her husband. The three tested positive for the coronavirus on Friday and Saturday, and were immediately put under medical quarantine, the report said. The city government has launched an investigation and begun testing people who have been in contact with them, it said. As well as the hospital, the residential compounds in which the three people live have been closed, and all of the sites have been sanitised, the health commission said. “We remind all local people to enhance self-protection, wear masks, wash your hands, observe social distancing, and cooperate with the local government on health monitoring,” it said. The city screened more than 178,000 people for Covid-19 last month , after two workers at the city’s port were confirmed as being asymptomatic cases. The Dalian Centre for Disease Control and Prevention issued a notice on Sunday advising people to closely watch for developments in Qingdao and avoid travelling to the city. The city sits across the Bohai Strait from Dalian, another Chinese port city that has only recently recovered from a coronavirus outbreak in July . Authorities in Dalian reported 92 locally transmitted cases and 26 asymptomatic cases after a worker at a local seafood processing company was found to be infected. The discovery led to the mass screening of 6 million people. China returned to work this week after the annual National Day holiday , which saw millions of holidaymakers and day trippers visiting tourist attractions and scenic spots across the country. Many of them shunned masks and social distancing rules. At a banquet at the Great Hall of the People in Beijing on September 30 to mark the start of the holiday, Chinese Premier Li Keqiang spoke of the country’s success in containing Covid-19, which has so far claimed the lives of more than 1 million people around the world.