Shanghai: China’s Qingdao city said on Monday it will conduct COVID-19 tests for the entire population of more than 9 million people over five days after new cases appeared linked to a hospital treating imported infections.

The city reported six new COVID-19 cases and six asymptomatic cases as of late Oct. 11. Most of the cases were linked to the Qingdao Chest Hospital.

The National Health Commission’s (NHC) tally of 21 confirmed COVID-19 cases in mainland China for Oct. 11 was published after Qingdao’s announcement, but did not include any confirmed infections in the city and it was not immediately clear why.

The number of new asymptomatic cases, which China does not count as confirmed cases, rose to 32 from 23 a day earlier, the NHC said. It did not offer a breakdown on where the new asymptomatic cases were reported, though it said 29 of these cases were imported infections.

Daily COVID-19 infections in mainland China has fallen drastically from peaks early this year, but the country remains on high alert in order to prevent painful lockdowns that led to an outright contraction of the world’s No. 2 economy.

Qingdao has already locked down Qingdao Chest Hospital as well as the emergency department of its central hospital. Buildings that the infected individuals live in have also been locked down as part of the virus containment measures.

The total number of confirmed COVID-19 cases in mainland China now stands at 85,578, while the death toll remained unchanged at 4,634.