The country where the virus first emerged has largely controlled its outbreak, cutting a stark contrast to many parts of the world still afflicted by rolling lockdowns and high case numbers.

On Sunday, six cases were confirmed in Qingdao -- a northeastern city of 9.4 million -- originating in a hospital, the Qingdao municipal health commission said in a statement on Monday.

Five districts will be tested "within three days" and the whole city "within five days", the statement said. However, officials did not give a precise figure on how many people would be tested.

China has extensive, quick test capabilities and the health commission said over 140,000 employees of "medical institutions, newly admitted patients and personnel" have already been tested in Qingdao since the cases were confirmed.

In June, large areas of the capital Beijing were subject to mass tests after the city of more than 20 million detected virus cases linked to a food market.

China has bounced back since the virus emerged late last year and forced widespread lockdowns that hammered the world's second-largest economy.

Hundreds of millions travelled across China for the 'Golden Week' holiday last week as the country edges back to growth, while rapid tests and swift lockdowns have tamped down secondary waves of the virus.

China is also desperate to be first to conjure up a coronavirus vaccine, with several companies in final-stage trials.

Although unproven, vaccines have already been administered to hundreds of thousands of key workers and soldiers as China seizes the pandemic narrative to show off the country's resilience and the Communist government's ability to handle the crisis.