A medical worker takes a swab sample from an elderly man for COVID-19 test at a testing site in Nanjing, east China's Jiangsu Province, July 21, 2021.(Photo: Xinhua)
The latest research by a Chinese team could save people from the discomfort of taking a throat or nasal swab for COVID-19 nucleic acid testing, and save time too, as a new test method only requires the patient to exhale into a bag for 30 seconds, with 5-10 minutes needed to finish the analysis.
The Global Times on Wednesday learned from the team leader Yao Maosheng, a professor at the College of Environmental Sciences and Engineering at Peking University, that the test is highly accurate, and can differentiate among COVID-19 carriers, healthy people and patients of other respiratory infections.
The study was based on exhalations of 74 COVID-19 patients, 30 patients with other respiratory infections and 87 healthy people. There are 12 signal breath-borne volatile organic compounds (VOCs) from their exhalations, which can be regarded as "fingerprints."
Higher levels of propanol were detected in the exhaled breath of COVID-19 patients and other respiratory infections than healthy subjects, while breath-borne acetone was found to be significantly lower for COVID-19 patients than those with other respiratory infections, Yao said.
Based on the 12 signal VOCs, an algorithm was created, and verification of the algorithm found its accuracy ranges from 91 to 100 percent.
The quick procedure and high accuracy give the new method an edge in comparison with the antigen-based quick testing. Yao told the Global Times the new technology didn't require any reagents and has a lower detection limit for detecting VOC species.
The new method is also cheap, costing 10 yuan ($1.5) in comparison with a nucleic acid test that charges 80 yuan for takers.
The test is capable of identifying a COVID-19 infected person with a false negative throat swab test. Asymptomatic and pre-symptomatic infections can be detected early, the Global Times learned.
The research was co-conducted by the Laboratory of Environmental Simulation and Pollution Control of Peking University and Chaoyang district's Center for Disease Control and Prevention in Beijing.
With this VOCs analysis, there could be false positives but no false negatives, making this an ideal method to supplement nucleic acid testing, the Global Times learned.
It can be used in various scenarios, including the Beijing Winter Olympics, Yao said. But the expert noted that as China doesn't have many cases, further data and validation tests may be needed before the technology is applied.
