The nucleic acid testing stock of the clinically confirmed and suspected close contact cases of novel coronavirus has all been cleared by Friday after 40 relevant laboratories in the city worked together, with an average daily testing volume of 14,000.

A staff member works at the health and quarantine comprehensive laboratory of Sichuan International Travel Health Care Center (Chengdu Customs Port Outpatient Department), in Chengdu, southwest China's Sichuan, Feb. 15, 2020. (Photo: Xinhua)

Less than 20 percent of the samples sent to Zhongnan Hospital of Wuhan University tested positive recently, down sharply from more than 60 percent of the nucleic acid samples in late January and early February, according to Li Yirong, director of the medical laboratory department of the hospital.

The apparent reduction in positive rates may be partly due to the recent testing of more samples from patients who are about to be discharged, or suspected cases and close contacts, unlike earlier samples that were taken from newly admitted patients, said Li.

Currently, the nucleic acid testing capacity in Wuhan is 20,000 people daily, with a total of 42,515 nucleic acid tests concluded in the last three days, after the center of the ongoing outbreak ramped up efforts in treating four types of personnel – the confirmed cases, suspected ones, cases that cannot rule out the possibility of infection, and those who have had close contact with the infected patients.

Local government has improved testing efficiency by instructing hospitals with testing capabilities to complete the process from clinical sampling to issuing test results within no more than 10 hours.

Wuhan recently launched an online novel coronavirus nucleic acid results tracking system for the public, enabling patients to check the results on their mobile phones on the first pass since February 19.

Samples, including throat swabs, nose swabs, and sputum swabs, go through a rigorous process of testing from specimen receipt, labeling, information registration, nucleic acid extraction, to electronic testing.

"In terms of testing alone, patients can get nucleic acid results in as quickly as two hours," said Li. Results of samples taken from patients after 5 pm are likely to be returned the next morning, as samples are sent in scattered ways, while tests are conducted in batches, Li said.