Clinical evaluation of a RT-LAMP SARS-CoV-2 test for the Point-Of-Care, rapid, low-cost, integrating sample solid phase extraction and on which reagents are lyophilized. (preprint)

Objectives: Determine the sensitivity and specificity of a Point-Of-Care test (COVIDISC) for SARS-COV2. The novelty of the test is to integrate, on the same (low-cost) compact plastic/paper device, solid phase RNA extraction and RT-LAMP amplification, all reagents being freeze-dried on it. Method: Retrospective study with a cohort of 99 patients characterized by real-time RT-PCR. The 37 positive naso-pharyngeal samples cover a broad range of viral loads (from 5 gc /microL to 2 10^6 gc/ microL of sample) . Results: The COVIDISC found 36 positives (out of 37 by IP4 RT-PCR protocols) and 63 negatives (out of 62 by RT-PCR). Conclusion: The sensitivity of the COVIDISC, found in this 99-patient retrospective study, is 97% and the specificity 100%.

Highly performing point-of-care molecular testing for SARS-CoV-2 with RNA extraction and isothermal amplification. (preprint)

In order to respond to the urgent request of massive testing, developed countries perform nucleic acid amplification tests (NAAT) of SARS-CoV-2 in centralized laboratories. Real-time RT - PCR (Reverse transcription - Polymerase Chain Reaction) is used to amplify the viral RNA and enable its detection. Although PCR is 37 years old, it is still considered, without dispute, as the gold standard. PCR is an efficient process, but the complex engineering required for automated RNA extraction and temperature cycling makes it incompatible for use in point of care settings. In the present work, by harnessing progress made in the past two decades in DNA amplification, microfluidics and membrane technologies, we succeeded to create a portable test, in which SARS-CoV-2 RNA is extracted, amplified isothermally by RT - LAMP (Loop-mediated Isothermal Amplification), and detected using intercalating dyes or highly fluorescent probes. Depending on the viral load, the detection takes between twenty minutes and one hour. Using pools of naso-pharyngal clinical samples, we estimated a sensitivity comparable to RT-qPCR (up to a Cycle threshold of 39, equivalent to <0.1 TCID50 per mL) and a 100% specificity, for other human coronaviruses and eight respiratory viruses currently circulating in Europe. We designed and fabricated an easy-to-use portable device called "COVIDISC" to carry out the test at the point of care. The low cost of the materials along with the absence of complex equipment paves the way towards a large dissemination of this device. The perspective of a reliable SARS-CoV-2 point of care detection, highly performing, that would deliver on-site results in less than one hour, with a self-testing potential, opens up a new efficient approach to manage the pandemics.