BEIJING, CHINA - OCTOBER 04: Chinese tourists walk on a crowded section of the Great Wall at Badaling after tickets sold out during the 'Golden Week' holiday on October 4, 2020  in Beijing, China. Officials are expecting the Golden Week holiday to boost China's consumer economy as people were encouraged to use the 8-day break to travel and spend. Tourist sites including the Great Wall were packed, with tickets selling out most days given pandemic restrictions and capacity capped at 75%.  (Photo by Kevin Frayer/Getty Images)
See tourists swarm China during Golden Week
02:35 - Source: CNN
CNN  — 

A coronavirus outbreak in the Chinese city of Qingdao, which prompted mass testing of millions of residents, has been traced back to two dock workers, authorities said on Friday.

A total of 12 locally transmitted cases were reported last weekend at the Qingdao Chest Hospital, sparking fears of a wider outbreak. City officials took immediate action and in just four days, they tested more than 10 million people, according to Qingdao’s Information Office.

So far, no new cases have been identified in relation to the cluster. One new case has been found, separate from the cluster.

The two dock workers, named Dong and Chen, tested positive for Covid-19 on September 24 and were sent for treatment and quarantine at Qingdao Chest Hospital, according to city officials.

Officials said that the men had CT scans, and the room was not disinfected in the correct way – contamination that then caused the hospital cluster.

Qingdao is a large port city on China’s eastern coast, home to numerous beaches and popular with tourists.

Already, heads are rolling; the director of the Qingdao Health Commission and the president of the Qingdao Chest Hospital were removed from their posts on Thursday, according to a statement from the city government.

China has had the virus under control since early spring. There have been a few flare-ups, including one in the capital Beijing, but authorities managed to contain each cluster within a few weeks using mass testing, thorough contact tracing, and reimposed restrictions.