More than four million coronavirus test swabs have been taken in a matter of days in Qingdao, the Chinese port city where a minor outbreak elicited a sweeping health response.
Queues for testing stretched across the eastern city for a another day on Tuesday after authorities detected six virus cases on the weekend and swiftly swung into action to head off a wider outbreak.
In scenes which contrasted with the fumbled efforts of other nations to establish effective screening regimes, Qingdao health workers in protective gear set up tents to take samples across neighbourhoods.
Residents said on social media that community representatives informed them of their nearest testing stations, with local districts helping to organise sample collection for mass testing.
"4.2 million samples have been collected for nucleic acid testing" as of Tuesday afternoon, city authorities said in a press conference reported by state media, adding that 1.9 million results had been obtained.
Except for the six confirmed cases and six asymptomatic infections earlier announced, no new cases have been found, the report added.
The city is aiming to test its entire population -- around 9.4 million -- within five days of the detection of the first cases at a hospital on Sunday.
China has paraded its rapid testing capacities during previous minor outbreaks and the ruling Communist Party is desperate to show its ability to manage the pandemic to its citizens -- as well as to foreign audiences -- after it emerged in the central city of Wuhan late last year.
The country has bounced back since the virus emerged late last year and forced widespread lockdowns that hammered the world's second-largest economy.
China is also desperate to be the first nation to produce a coronavirus vaccine, with several companies in final-stage trials.