Low-cost diagnostic tool delivers COVID-19 test results in under an hour

An affordable new diagnostic tool that delivers COVID-19 test results in under an hour could help boost pandemic preparedness in resource-poor regions, according to a team of researchers.

The reverse transcription loop-mediated isothermal amplification (RT-LAMP) test detects SARS-CoV-2 from saliva samples without the need for RNA extraction — making it faster and more affordable than traditional methods and better suited for use in low-resource settings.

In addition to COVID-19, the tool can also detect other RNA viruses of public health concern such as Dengue, Zika and Chikungunya, according to researchers from Italy, India, South Africa and Slovenia.

Unlike the gold-standard polymerase chain reaction (PCR) tests which require high-end laboratory equipment, RT-LAMP can be used in field settings and relies only on a basic heat source.

"The key strength of this study lies in its comprehensive, multi-country clinical evaluation of an innovative molecular diagnostic tool, specifically in — and for — Africa," said Alessandro Marcello, head of molecular virology at the International Centre for Genetic Engineering and Biotechnology, in Trieste, Italy and one of the authors of the research, published in The Lancet Global Health.

"This work is a milestone in the process of building sustainable diagnostic capacity for infectious diseases on the African continent," said Marcello, who also leads EXPANDIA, a laboratory network for testing cost-effective diagnostic technologies for limited-resource settings.

The study analysed more than 2,700 nasopharyngeal swabs and nearly 600 crude saliva samples collected in Kenya, Ethiopia, Nigeria and Angola.

It found RT-LAMP had 89 per cent sensitivity and 95 per cent specificity in swab samples compared to RT-qPCR, and 80 per cent sensitivity and 99 per cent specificity in unprocessed saliva samples.

Sensitivity and specificity are two key measures of a diagnostic test's accuracy, with sensitivity referring to a test's ability to correctly identify individuals who have the disease and specificity referring to its accuracy in identifying those who do not.

"These results suggest that colorimetric RT-LAMP offers a scalable, cost-effective tool for pandemic surveillance, particularly for resource-poor settings," the study authors said.

Marcello explained that while RT-PCR remains the diagnostic gold standard, its reliance on thermocyclers and fluorescent probes limits its use in many parts of Africa.

In contrast, RT-LAMP amplifies viral RNA at a constant temperature and provides colour-coded results visible to the naked eye.

It is more accurate than the rapid antigen tests that are used for COVID-19 in many high-income areas, especially when performed on people with no symptoms or to find new variations.

To test its real-world application, the team partnered with the Gates Foundation and New England Biolabs, an American life sciences company, to evaluate the tool across ten Sub-Saharan African countries.

"This initiative involved not just analytical validation but also clinical trials to assess the sensitivity and specificity of RT-LAMP in real-world settings, which is essential for regulatory approval and diagnostic use," Marcello told SciDev.Net.

"We did not limit our effort to clinical accuracy studies," he added.

"We developed a full programme including engagement with regulatory bodies, genomic surveillance to ensure local virus strain detection, exploration of local reagent manufacturing, and scouting for robust low-cost technologies in India and China."

The team is now expanding the use of RT-LAMP to other priority diseases in Africa, including arboviruses such as dengue and Zika.

"In short, this research was born out of an urgent public health need and has evolved into a multi-faceted initiative to strengthen diagnostic readiness and resilience in low-resource settings," Marcello said.

Robyn Meurant, principal consultant at ACT-IVD, a diagnostics regulatory consultancy, said the findings show the importance of self-sufficiency in testing capacity across Africa.

"During COVID, the continent was left without testing capabilities as manufacturers focused their sales in higher income settings," Meurant told SciDev.Net.

"The recent withdrawal of funding from the US government to many organisations such as WHO and USAID reinforces the need for more self-directed and sustainable solutions for African countries."

Meurant said given the scarcity of high-end diagnostic capacity, the RT-LAMP is "a valid and acceptable solution" that offers reliable results.

"Its utility in this setting can only increase," she added.