New COVID-19 Rapid Diagnostic Approved On ‘GeneXpert’ TB Platform; Could Pave Way For More Testing In Low- & Middle-Income Countries
Technician in Indonesia runs a test on a GeneXpert machine (Source: USAID)

US Food & Drug Administration authorization of a rapid COVID-19 test on the GeneXpert platform, one of the most widely-used TB diagnostic tools in the world, could be the first crack in the doorway to wider testing capacity in low- and middle-income countries, leading TB advocates told Health Policy Watch

There are some 23,000 GeneXpert devices worldwide, including an estimated 7000 -10,000 instruments scattered across Africa, Latin America and South-East Asia. While not a high-throughput device, the GeneXpert technology produced by the California-based firm Cepheid, can process nose swab samples in a mere 45 minutes, and perform up to 96 tests in 24 hours. 

Cepheid received the US FDA emergency use authorization on Friday, March 20th  for its new Xpert® Xpress SARS-CoV-2 diagnostic that can be processed on the GeneXpert platform. 

“The GeneXpert® platform could fill a crucial need, especially in low- and middle-income countries,” said Paula Fujwara, Scientific Director of the International Union Against Tuberculosis and Lung Disease (The Union). “The need for testing is immense as we still don’t know the true number of people who are infected in the world,” she added, and adapting the GeneXpert platforms in low- and  middle-income countries to COVID-19 testing coud be “easily and rapidly done,” since the technology is already well-known.

However, she called on Cepheid to reduce the price of the COVID-19 test cartridges, which are reportedly set to sell for US$20 initially, to US$5 each, in order to make them more widely affordable in low- and middle-income countries. 

Many other pathogens, including HIV and hepatitis C, are also tested on GeneXpert, at a cost of between $US 9 – $US 20, to some 145 low- and middle-income countries that are eligible to procure the diagnostics at concessionary prices.

In December 2019, Médecins Sans Frontières/Doctors Without Borders called upon Cepheid to reduce the costs of all its test cartridge to US$5, including service and maintenance, eligible countries.  

GeneXpert was widely deployed about decade ago to rapidly detect tuberculosis, including multi-drug resistant strains; it has since been adapted to enable rapid testing of many her pathogens, including not only HIV and hepatitis C, but also influenza, Ebola and sexually transmitted infections. 

Thanks to longstanding investments in TB infrastructure by The Global Fund, among others, the GeneXpert instruments are widely available in WHO’s Africa Region, which has now reported 1,396 confirmed COVID-19 cases across 43 countries. For instance, there were approximately 150 machines installed and running in the Democratic Republic of Congo, and ‘several “hundreds in nearby countries”, according to a 2018 report from Nature.

GeneXpert tests are a “point-of-care” option that allows  hospitals and clinics to perform diagnostic tests in-house, rather than sending them to outside labs. Additionally,  the machine’s “automated systems do not require users to have specialty training to perform testing — they are capable of running 24/7,” Cepheid President Warren Kocmond also noted in a press release.

“During this time of increased demand for hospital services, Clinicians urgently need an on-demand diagnostic test for real-time management of patients being evaluated for admission to health-care facilities,” said  David Persing, Chief Medical and Technology Officer at Cepheid.

“An accurate test delivered close to the patient can be transformative — and help alleviate the pressure that the emergence of the 2019-nCoV outbreak has put on healthcare facilities that need to properly allocate their respiratory isolation resources.”

The new COVID-19 tests for the system will be shipped out from the Sunnyvale, California production facility starting this week.

The first diagnostic tests appear to be destined for US domestic use, where there are approximately 5,000 machines, a source with another TB advocacy group told Health Policy Watch.

“It appears that Cepheid is not yet positioning the COVID test for wide -scale use in low-income countries, where it could have the greatest impact,” the source said.

Still, there is a “strong case” for activists to push “for ramping up global production to meet the testing needs of many low-income countries,” where GeneXpert networks are already in place.

Usability In Rough Field Settings Still A Concern

While automated, and designed for point-of-care testing, GeneXpert requires controlled, air-conditioned temperatures, so it’s not suitable for rough field conditions.  However, it is still widely available in district health facilities and TB clinics across many low-income countries.

“The advantage of GeneXpert is that testing can be done closer to the point of care (rather than only in centralized laboratories), which theoretically would improve turn-around times for test results as compared to laboratory instruments,” the source told Health Policy Watch.

Ultimately, instrument-free immunoassays would be even cheaper and more appropriate for community-level testing. There are a number rapid tests in the pipeline, but  none so far have been approved. 

In arrangements made a decade ago, prices for the GeneXpert device, which normally costs about US$17,000, as well as cartridge prices were reduced, for 145 eligible low- and middle-income countries. In 2016 alone, 6.9 million cartridges were procured in the public sector under the concessionary pricing arrangements. 

Tsering Llamo and Grace Ren contributed to this story

Updated 24 March, 2020. 

Image Credits: Trishanty Rondonuwu, USAID Challenge TB.