Mass testing a go-to response

"To prepare for sudden outbreaks, we have stocked up on consumable equipment, and all laboratory workers are on standby. We are ready to set off any time," Wang said.

"Upon being dispatched to a hospital, we will coordinate with local health workers and smooth out working procedures, which will help yield results more quickly," she added.

Absorbing lessons from the initial wave of outbreaks in Hubei, China has also stepped up local preparedness by enhancing infrastructure and training.

As of late June, China is capable of conducting nucleic acid tests on 3.78 million people per day, up from 1.26 million in early March, according to Guo Yanhong, an official with the National Health Commission's medical supervision and administration department.

The number of testing facilities more than doubled from 2,081 in early March to 4,804 in late June, and the number of testing personnel stood at over 28,000 nationwide, according to Guo.

"To teach a health worker how to conduct tests only takes a few days, but their roles in ensuring the speed and precision of nucleic acid tests are crucial," Wang said.

"Before wrapping up our work in Jilin, Jilin province, which was hit with an outbreak in May, we trained laboratory workers from three local hospitals on performing tests. They have now obtained certificates to run tests independently for the novel coronavirus," she said.

Peng, from Guangdong province, said with current stockpiles of equipment and personnel, meeting the national requirement of reporting test results to people visiting fever clinics within six hours is easily within reach.

However, even with a significant ramp-up in testing capacity, abrupt outbreaks affecting a large population may result in temporary shortages.

Guo, from the National Health Commission, said that during the recent outbreak in Beijing tied to a wholesale food market, demand had outpaced the capital's testing capability for a short period.

"To address the testing shortage, 20 testing teams from 12 provinces were dispatched to Beijing," she said. "We also deployed mobile laboratories and carried out mixed testing in low-risk groups to increase efficiency."

The mixed testing method, which typically involves blending five samples together for tests, is projected to raise the number of samples being processed per day in Beijing from 400,000 to 1 million per day, according to Guo.

A noticeable outcome of mass testing is a growing pool of asymptomatic cases, which would have gone unnoticed because they lack symptoms.

In the past week, Urumqi has detected from 13 to 38 asymptomatic infections on a daily basis. As of Wednesday, 143 symptom-free virus carriers are under medical observation.

Zhang Wei, director of the city's health commission, said all asymptomatic cases were identified through the free, citywide screening effort.

"Some of them are in an incubation period now and will be re-diagnosed as confirmed cases later," he said. "The earlier we confirm cases, the faster can we deliver treatment and alleviate their symptoms."

Wu Zunyou, chief epidemiologist with the Chinese Center for Disease Control and Prevention, also said during an interview with China Central Television on Wednesday that in Dalian, the majority of confirmed cases have been found in previously asymptomatic patients that were already under medical observation.

"That means these new cases are under the management of local health authorities and will not cause wider transmissions," he said.