Versatile and flexible microfluidic qPCR test for high-throughput SARS-CoV-2 and cellular response detection in nasopharyngeal swab samples.

The emergence and quick spread of SARS-CoV-2 has pointed at a low capacity response for testing large populations in many countries, in line of material, technical and staff limitations. The traditional RT-qPCR diagnostic test remains the reference method and is by far the most widely used test. These assays are limited to a few probe sets, require large sample PCR reaction volumes, along with an expensive and time-consuming RNA extraction step. Here we describe a quantitative nanofluidic assay that overcomes some of these shortcomings, based on the BiomarkTM instrument from Fluidigm. This system offers the possibility of performing 4608 qPCR end-points in a single run, equivalent to 192 clinical samples combined with 12 pairs of primers/probe sets in duplicate, thus allowing the monitoring of SARS-CoV-2 including the detection of specific SARS-CoV-2 variants, as well as the detection other pathogens and/or host cellular responses (virus receptors, response markers, microRNAs). The 10 nL-range volume of BiomarkTM reactions is compatible with sensitive and reproducible reactions that can be easily and cost-effectively adapted to various RT-qPCR configurations and sets of primers/probe. Finally, we also evaluated the use of inactivating lysis buffers composed of various detergents in the presence or absence of proteinase K to assess the compatibility of these buffers with a direct reverse transcription enzymatic step and we propose several protocols, bypassing the need for RNA purification. We advocate that the combined utilization of an optimized processing buffer and a high-throughput real-time PCR device would contribute to improve the turn-around-time to deliver the test results to patients and increase the SARS-CoV-2 testing capacities.

The first wave of COVID-19 in hospital staff members of a tertiary care hospital in the greater Paris area: A surveillance and risk factors study.

INTRODUCTION: Understanding how hospital staff members (HSMs), including healthcare workers, acquired severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) during the first wave can guide the control measures in the current second wave in Europe. METHODS: From March 5 to May 10, 2020, the Raymond-Poincaré Hospital held a weekday consultation for HSMs for PCR testing. HSMs were requested to complete a questionnaire on their potential exposure to SARS-CoV-2. RESULTS: Of 200 HSMs screened, 70 tested positive for SARS-CoV-2. Ninety-nine HSMs completed the questionnaire of whom 28 tested positive for SARS-CoV-2. In the multivariable analysis, age of ≥44 years (aOR = 5.2, 95% CI [1.4-22.5]) and not systematically using a facemask when caring for a patient (aOR = 13.9, 95% CI [1.8-293.0]) were significantly associated with SARS-CoV-2 infection. Working in a COVID-19-dedicated ward (aOR = 0.7, 95% CI [0.2-3.2]) was not significantly associated with infection. Community-related exposure in and outside the hospital, hospital meetings without facemasks (aOR = 21.3, 95% CI [4.5-143.9]) and private gatherings (aOR = 10, 95% CI [1.3-91.0]) were significantly associated with infection. CONCLUSIONS: Our results support the effectiveness of barrier precautions and highlight in-hospital infections not related to patient care and infections related to exposure in the community. Protecting HSMs against COVID-19 is crucial in fighting the second wave of the epidemic.

microFLOQ® Direct: a helpful tool for the coronavirus SARS-CoV-2 rapid detection without RNA purification (preprint)

In the context of SARS-Cov-2 virus disease (COVID-19) pandemic, molecular diagnostic tools were rapidly developed as there are fundamental for a rapid detection of infected people. In this context, and in order to optimize the manipulations and reduce the time to get results, we report the successful use of a sampling tool for COVID-19 diagnosis named microFLOQ® Direct (MFD). Hundred upper respiratory specimens sampled from patients with potential COVID-19 were evaluated using MFD, and results were compared to the results obtained by standard sampling procedure using dry swabs and physiologic serum as the transport medium. MFD results compared to results issued from the classic RNA purification and amplification steps from transport medium showed that MFD can be directly used for RT-PCR analysis without the preliminary inactivation and extraction steps. So, MFD could limit handling errors compared to the different treatment steps with dry swabs and transport medium. It therefore limits the risk of contamination, simplify the analytical process and enables to get results in less than 2 hours. We also show that the MFD kit is operational as a screening tool in the field of molecular detection of viral and bacterial diseases during an outbreak and then it can be used for public health or agro-veterinary purposes.