Meanwhile, here in China, authorities in Qingdao say they have completed a mass testing campaign of its eleven million residents. A number of locally-transmitted cases were reported in the coastal city last weekend, sparking fears of a wider outbreak.

Our reporter Cao Bing visited a laboratory there to learn more about the testing process.

These inflatable rooms are the final stop for a million test samples in Qingdao.

CAO BING Qingdao "This is Qingdao's Huoyan lab. There are nine cabins. Each group of three forms one single laboratory. They are testing a tenth of the samples collected in Qingdao."

There are three separate stages in testing the samples. Each takes place in a different cabin. Preparing the samples on a plate, extracting the DNA from the samples, and finally testing them with the machine.

Each lab tests nearly 2,000 samples at a time and the whole process takes about 4 hours. The work continues around the clock.

TIAN XIUYING HR Manager BGI Qingdao "There are over 300 people working here. About a hundred of them were sent from cities like Tianjin and Shenzhen. They work in 2 shifts, to cover 24 hours a day."

Time is tight and the workload is heavy, but they say that accuracy is assured.

LIU JUNNIAN General Manager BGI Qingdao "All the facilities here are designed in China and Made in China, and are very stable and precise, especially when we are doing it in a large scale."

The manager says high efficiency of the work helps the government grasp the situation and gives residents a sense of security. And he's happy that no positive cases have been found in samples here. CAO BING, CGTN, Qingdao, Shandong Province.