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COVID-19 Updates: How Does the GeneXpert Test for COVID-19 Work?

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KIU, Western Campus – According to the Daily Monitor of Tuesday 12th May, the Ugandan government launched the use of GeneXpert machines at border points to enable truck drivers to be tested for COVID-19 and receive their results before they proceed into the country.

This followed a sharp rise in Uganda’s COVID-19 confirmed cases caused by many positive cases amongst truck drivers, almost on a daily basis.

It is on the basis of this that the Ministry of Health piloted the GeneXpert test at the Mutukula and Malaba border points, according to the Daily Monitor report.

Today, we look at the GeneXpert technology and try to understand how it works, and whether it can tackle the problem of truck drivers bringing Coronavirus into the country.

The Xpert® Xpress SARS-Cov-2 is a rapid, near-patient test for detection of the 2019 novel Coronavirus that causes COVID-19. It was authorized by the United States of America’s Food and Drug Authority (FDA) in March, for emergency use in testing suspected patients.

According to Cepheid.com, the website for Cepheid Inc, the manufacturers of the technology, the test leverages the principles of the current Xpert® Xpress Flu/RSV cartridge technology, in which multiple regions of the viral genome are detected.

According to Cepheid’s Chief Medical Officer, Dr David Persing, patients will be able to get results whether they are showing symptoms or not.

Explaining how the test works, Dr Persing says the sample is taken and put into a test-tube and using a pipette, it’s then transferred into the cartridge, which already includes the testing reagents. 

The lid of the cartridge is closed and it’s placed in the GeneXpert system which then determines whether the sample is positive or negative. He says the system can run multiple tests simultaneously.

To watch the video demonstrating how the test works, click here.

The test can be utilized in multiple settings where actionable tests are needed to make informed treatment decisions quickly, as in the case of truck drivers. It delivers point-of-care results with the same level of performance seen in reference labs.

Point-of-care testing (POCT) encompasses any tests that are performed at or near the patient and at the site where care or treatment is provided. This contrasts with the current pattern where testing is done at the Uganda Virus Research Institute (UVRI) in Entebbe, and with POCT, results are available relatively quickly so that they can be acted upon without delay.

In this case, a truck driver will be able to be subjected to a test, and within 45 minutes the results will be received in order to determine whether this truck driver can proceed into the country or be quarantined at the border or even turned back to the country they came from.

Ritah Kiconco, a laboratory scientist at KIU Teaching Hospital said that the GeneXpert test is commonly used for testing Tuberculosis (TB) but modifications in the technology have made it possible to use it for testing COVID-19 as well.

Quoting a WHO report on GeneXpert testing for COVID-19, Kiconco said, "With the current pandemic of COVID-19, special cartridges have been developed to be used on GeneXpert equipment to detect COVID-19."

"Although these haven't gained wide usage in Africa, the WHO gave European nations the go-ahead to use it in identifying their cases," she added.

Picture Credit: researchgate.net