New Covid-19 test kits in China give answers within 45 minutes


  • China
  • Thursday, 16 Apr 2020

A patient being given a nucleic acid test at Wuhan No 4 Hospital in Hubei province.- China Daily

BEIJING (China Daily/ANN): The Chinese Academy of Sciences announced on April 9 that its biomedical institute in Suzhou, Jiangsu province, had created a nucleic acid test kit that could produce results in just 45 minutes.

The kit, which also enables on-site testing, can be stored and transported at room temperature.

Wang Daming, leader of the research team at the academy's Suzhou Institute of Biomedical Engineering and Technology, started working on the kit in January. The following month, he went to Hubei province to test its efficacy.

The kit only requires 20 microlitres of nasal swab or mucus samples to produce a result, the institute said.

A single test machine can analyse 60 samples an hour, it said, adding that more than 600 patients had been tested with an accuracy rate of over 99 per cent. The cost of the testing was not disclosed.

China has been striving to develop more advanced test kits while also tightening regulations for manufacturers.

Beate Trankmann, the United Nations Development Programme resident representative for China, said the country is one of the few markets that has not banned exports of medical supplies and is actively supporting global procurement to fight the novel coronavirus pandemic.

"What's impressive is the bilateral aid that China is putting forward," she said, adding that it is encouraging to see the nation "returning the favour after having received international assistance at the very beginning of the pandemic".

The kit developed by Wang's team uses a new technique called Hybrid Capture Immunofluorescence Analysis, or HC-IFA, which can dissolve the pathogen's exterior and directly detect the genetic material of the virus.

One of this method's biggest strengths is that it does not require polymerase chain reaction, or PCR, a commonly used process in nucleic acid test kits to amplify the Covid-19 viral signals for detection. The shortened procedure reduces the possibility of human error, making the new method less susceptible to false results.

Moreover, conventional PCR nucleic acid test kits must be transported in special cooling containers that use a considerable amount of dry ice, which has a surface temperature of minus 78 C.

However, only a few logistical companies can meet this transportation requirement, according to Zhou Yan, operations supervisor for Shanghai BioGerm Medical Biotechnology Co. This is because of dry ice's ability to quickly transmute into carbon dioxide, making it dangerous to store in a confined area, such as the cargo hold of an airplane.

The new test kit bypasses this problem, as its reagents are not as sensitive to temperature, so it is cheaper and more convenient to ship worldwide. The kit was approved by the National Medical Products Administration, or NMPA, on March 24.

The Conformite Europeenne, or CE, mark is also being sought from the European Union, the institute said. Since 1985, the CE has been the EU's mandatory conformity marking for regulating goods sold within the European Economic Area.

Wang Yuedan, an immunology professor at Peking University, who was not involved in creating the test kit, said the new technique can be used to test for the virus, but it requires a special machine.

The professor has doubts over its cost-effectiveness for mass diagnosis.

Zhang Shuyang, vice-president of Peking Union Medical College Hospital, said two of the most popular diagnostic methods for Covid-19 are PCR nucleic acid tests and antibody tests. The former is a tried-and-trusted method that is cost-effective for large scale diagnosis, as it only requires the use of swabbed tissue.

Based on Zhang's experience, nasal swabs are more accurate than throat swabs, but both methods may not include as much viral content as extracting fluid from the lower respiratory tract, which consists of the trachea and the lungs, she said.

"Samples collected from the lower respiratory tract tend to yield fairly accurate test results, because that's where the virus mostly resides," she said.

However, this procedure is more time-consuming and difficult to conduct, and should be reserved for patients with more pronounced symptoms.

Feng Luzhao, a researcher from the Chinese Center for Disease Control and Prevention, said at a news briefing last month that the average waiting time for nucleic acid testing results in China is about two to three hours, with a relatively high accuracy rate.

However, the time and accuracy may vary for test kits produced by other countries.

Another common issue with PCR nucleic acid tests is that they are prone to false results. Feng said the accuracy depends heavily on the quality of the test kit, how long a patient has been infected, and how rigorously the samples are collected, transported and processed.

Wang Jianbin, a researcher at the Center for Life Sciences jointly operated by Tsinghua University and Peking University, said a typical nucleic acid test kit has three components: the extraction reagent; enzymes and supporting chemicals; and primers.

The extraction reagent and supporting chemicals are genetic and can be found in other test kits, but the primers are uniquely designed to detect a specific pathogen. On Jan 21, Chinese scientists published genetic information about the primers, paving the way for other countries to develop their own kits.

Wang Jianbin said stepping up production too quickly could lead to quality control issues, because test kit manufacturers may not have the time or resources to optimize their products. This issue was especially prevalent during the early days of the outbreak in China.

Zhang said overworked staff members present another challenge that could hinder the accuracy of tests, adding,"If front-line medical workers are exhausted or not familiar with the test kit, they may not follow the detailed instructions properly."

According to the China Association for In-Vitro Diagnostics, laboratory testing for the novel coronavirus is highly dangerous.

Employees must wear protective gear that meets biological safety level 3 requirements, the third-highest on a four-tier system for handling dangerous pathogens such as yellow fever, West Nile virus and bacteria that cause tuberculosis.

Zhang said: "To protect the testing staff, the samples are often sterilized for at least 30 minutes at 56 C. This procedure may destroy the virus' genetic material, making it difficult to detect the pathogen."

To solve these problems, China has optimized its biosafety standards, reducing the need to unduly process the samples, she said. Dozens of advanced bioresearch facilities nationwide have also been mobilised to serve as test centres for the virus. - China Daily/Asia News Network

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