Photo: Xinhua

Chinese coronavirus (COVID-19) test kit manufacturer Guangzhou Wondfo Biotech said it is "surprised and disappointed" with the decision reached by the Indian Council of Medical Research (ICMR) to stop using the company's rapid antibody test kits, indicating that poor test procedures in India may have created inaccurate results.

"Wondfo SARS-CoV-2 Antibody Test (Lateral Flow Method) is one of the first tests to receive an import license from India and has been validated and approved by the ICMR through the National Institute of Virology (NIV), Pune," the company told the Global Times.

"We are confident in the quality of our products which meet standards in China and countries that we are exporting to," the company said.

The comment came as the ICMR recently announced it advised several states to stop using kits purchased from Chinese companies - Guangzhou Wondfo Biotech and Zhuhai Livzon Diagnostics - and send them back to suppliers. The research group claimed that an evaluation of the test kits revealed a "wide variation in their sensitivity, despite early promise of good performance for surveillance purposes."

Wondfo said it was investigating ICMR's concerns and stressed the use of appropriate and pertinent testing methods varies over the course of viral infection.

Based on the timing of the appearances of ribonucleic acid (RNA) indicating live virus and the two types (IgG / IgM) of antibodies in the human body, different testing methods are used to ensure the accuracy of test results, the company said.

An industry insider surnamed Chen echoed the company's sentiments, and said it is important that the test kits are used correctly.

Two different COVID-19 kits are currently available on the market. One checks for nucleic acid, and the other is an antibody test. The former works by detecting coronavirus nucleic acid from nasal and throat swabs, while the latter detects virus antibodies in blood serum or plasma.

"In practice, the accuracy of nucleic acid tests is affected by the characteristics of the virus, product itself as well as the collection, storage, and transport of samples. Meanwhile, reasonable timing is key for accurate antibody test results, as the amount of antibody in human bodies varies from time to time," Chen said.

Chen said the test kits have an application scope and are limited, adding that the instructions should be read carefully. Also, it's just as important to choose the right test kit and consider individual situations.

To date, Wondfo has delivered millions of its SARS-CoV-2 Antibody Test (Lateral Flow Method) to more than 70 countries and regions worldwide, of which over 1 million were exported to countries including Brazil, Spain, Indonesia and Venezuela.

Zhuhai Livzon Diagnostics was unavailable to comment by press time.