Optical imaging spectroscopy for rapid, primary screening of SARS-CoV-2: a proof of concept.

Effective testing is essential to control the coronavirus disease 2019 (COVID-19) transmission. Here we report a-proof-of-concept study on hyperspectral image analysis in the visible and near-infrared range for primary screening at the point-of-care of SARS-CoV-2. We apply spectral feature descriptors, partial least square-discriminant analysis, and artificial intelligence to extract information from optical diffuse reflectance measurements from 5 µL fluid samples at pixel, droplet, and patient levels. We discern preparations of engineered lentiviral particles pseudotyped with the spike protein of the SARS-CoV-2 from those with the G protein of the vesicular stomatitis virus in saline solution and artificial saliva. We report a quantitative analysis of 72 samples of nasopharyngeal exudate in a range of SARS-CoV-2 viral loads, and a descriptive study of another 32 fresh human saliva samples. Sensitivity for classification of exudates was 100% with peak specificity of 87.5% for discernment from PCR-negative but symptomatic cases. Proposed technology is reagent-free, fast, and scalable, and could substantially reduce the number of molecular tests currently required for COVID-19 mass screening strategies even in resource-limited settings.

SARS-CoV-2 not found in pressure injury exudates from COVID-19 patients.

BACKGROUND: The emergence of COVID-19 has become a global health emergency. The transmissibility of the disease is of great interest to healthcare workers and scientists alike. The primary route of transmission is via respiratory droplets, but viral RNA has also been found in feces and body fluids such as urine, serum, and semen. So far, there has been no report on whether SARS-CoV-2 is present in the exudates of cutaneous lesions. This study was designed to investigate whether SARS-CoV-2 can be found in the pressure injury exudates in patients with severe COVID-19 infections. METHODS: 46 critically ill COVID-19 patients who were admitted to the ICU of the Sino-French New City Branch of Tongji Hospital in Wuhan between February 4 and April 12 developed pressure injuries. 22 patients with pressure injuries had wound exudates. Wound and pharyngeal swabs of the 22 patients were collected and RT-PCRs were conducted to detect SARS-CoV-2 viral RNA. RESULTS: At the time of pressure injury, 5 patients still tested positive by pharyngeal swabs, the rest of the 17 patients tested negative. However, none of the wound exudate swabs from the participants tested positive for SARS-CoV-2 by RT-PCR. CONCLUSION: Our study suggests that it is rather unlikely that COVID-19 can be transmitted via pressure injury exudates, but we still recommend standardized personal protective equipment, face shield and an additional pair of gloves when treating pressure injuries.

Rapid Direct Nucleic Acid Amplification Test without RNA Extraction for SARS-CoV-2 Using a Portable PCR Thermocycler.

There is an ongoing worldwide coronavirus disease 2019 (Covid-19) pandemic caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). At present, confirmatory diagnosis is by reverse transcription polymerase chain reaction (RT-PCR), typically taking several hours and requiring a molecular laboratory to perform. There is an urgent need for rapid, simplified, and cost-effective detection methods. We have developed and analytically validated a protocol for direct rapid extraction-free PCR (DIRECT-PCR) detection of SARS-CoV-2 without the need for nucleic acid purification. As few as six RNA copies per reaction of viral nucleocapsid (N) gene from respiratory samples such as sputum and nasal exudate can be detected directly using our one-step inhibitor-resistant assay. The performance of this assay was validated on a commercially available portable PCR thermocycler. Viral lysis, reverse transcription, amplification, and detection are achieved in a single-tube homogeneous reaction within 36 min. This minimizes hands-on time, reduces turnaround-time for sample-to-result, and obviates the need for RNA purification reagents. It could enable wider use of Covid-19 testing for diagnosis, screening, and research in countries and regions where laboratory capabilities are limiting.