Engineering Innovative Interfaces for Point-of-Care Diagnostics.

The ongoing Coronavirus disease 2019 (COVID-19) pandemic illustrates the need for sensitive and reliable tools to diagnose and monitor diseases. Traditional diagnostic approaches rely on centralized laboratory tests that result in long wait times to results and reduce the number of tests that can be given. Point-of-care tests (POCTs) are a group of technologies that miniaturize clinical assays into portable form factors that can be run both in clinical areas --in place of traditional tests-- and outside of traditional clinical settings --to enable new testing paradigms. Hallmark examples of POCTs are the pregnancy test lateral flow assay and the blood glucose meter. Other uses for POCTs include diagnostic assays for diseases like COVID-19, HIV, and malaria but despite some successes, there are still unsolved challenges for fully translating these lower cost and more versatile solutions. To overcome these challenges, researchers have exploited innovations in colloid and interface science to develop various designs of POCTs for clinical applications. Herein, we provide a review of recent advancements in lateral flow assays, other paper based POCTs, protein microarray assays, microbead flow assays, and nucleic acid amplification assays. Features that are desirable to integrate into future POCTs, including simplified sample collection, end-to-end connectivity, and machine learning, are also discussed in this review.

Maintained imbalance of triglycerides, apolipoproteins, energy metabolites and cytokines in long-term COVID-19 syndrome patients.

Background: Deep metabolomic, proteomic and immunologic phenotyping of patients suffering from an infection with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) have matched a wide diversity of clinical symptoms with potential biomarkers for coronavirus disease 2019 (COVID-19). Several studies have described the role of small as well as complex molecules such as metabolites, cytokines, chemokines and lipoproteins during infection and in recovered patients. In fact, after an acute SARS-CoV-2 viral infection almost 10-20% of patients experience persistent symptoms post 12 weeks of recovery defined as long-term COVID-19 syndrome (LTCS) or long post-acute COVID-19 syndrome (PACS). Emerging evidence revealed that a dysregulated immune system and persisting inflammation could be one of the key drivers of LTCS. However, how these biomolecules altogether govern pathophysiology is largely underexplored. Thus, a clear understanding of how these parameters within an integrated fashion could predict the disease course would help to stratify LTCS patients from acute COVID-19 or recovered patients. This could even allow to elucidation of a potential mechanistic role of these biomolecules during the disease course. Methods: This study comprised subjects with acute COVID-19 (n=7; longitudinal), LTCS (n=33), Recov (n=12), and no history of positive testing (n=73). 1H-NMR-based metabolomics with IVDr standard operating procedures verified and phenotyped all blood samples by quantifying 38 metabolites and 112 lipoprotein properties. Univariate and multivariate statistics identified NMR-based and cytokine changes. Results: Here, we report on an integrated analysis of serum/plasma by NMR spectroscopy and flow cytometry-based cytokines/chemokines quantification in LTCS patients. We identified that in LTCS patients lactate and pyruvate were significantly different from either healthy controls (HC) or acute COVID-19 patients. Subsequently, correlation analysis in LTCS group only among cytokines and amino acids revealed that histidine and glutamine were uniquely attributed mainly with pro-inflammatory cytokines. Of note, triglycerides and several lipoproteins (apolipoproteins Apo-A1 and A2) in LTCS patients demonstrate COVID-19-like alterations compared with HC. Interestingly, LTCS and acute COVID-19 samples were distinguished mostly by their phenylalanine, 3-hydroxybutyrate (3-HB) and glucose concentrations, illustrating an imbalanced energy metabolism. Most of the cytokines and chemokines were present at low levels in LTCS patients compared with HC except for IL-18 chemokine, which tended to be higher in LTCS patients. Conclusion: The identification of these persisting plasma metabolites, lipoprotein and inflammation alterations will help to better stratify LTCS patients from other diseases and could help to predict ongoing severity of LTCS patients.

Toward rapid and sensitive point‐of‐care diagnosis with surface‐enhanced Raman scattering‐based optofluidic systems

With the recent global outbreaks of infectious diseases such as coronavirus disease 2019, developing a detection system capable of quickly and accurately diagnosing diseases on‐site has become a pressing need. The ability to diagnose patients in the field is crucial for the prompt isolation and treatment of infected individuals and the prevention of the spread of the disease. Our research group has recently developed a surface‐enhanced Raman scattering optofluidic system that enables rapid and accurate point‐of‐care diagnostics. This account will introduce the principle and configuration of the fluidic devices, such as lateral flow assay strips or microfluidic channels, and the portable Raman spectrometer. We will also highlight the challenges that must be addressed for using this system in clinical settings. Rapid and accurate diagnosis is critical for effective disease management and control, and developing this system can significantly improve our ability to respond to outbreaks of infectious diseases. [ FROM AUTHOR] Copyright of Bulletin of the Korean Chemical Society is the property of John Wiley & Sons, Inc. and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full . (Copyright applies to all s.)

[Evaluation of COVID-19 Antigen Test Kit Assay Analytical and Clinical Performance].

Objective To rapidly screen patients with novel coronavirus pneumonia (COVID-19) infection including asymptomatic ones. Method Established a rapid detection test kit, and evaluated analytical and clinical performance of it. Result The minimum limit of detection of the reagent was 9.75×102 TCID50/mL; there was no cross-reaction and interference in the high-concentration samples of 29 common respiratory pathogens tested. The diagnostic sensitivity of clinical samples was 98.56%, specificity was 99.00%, and the total coincidence rate was 98.85%; the consistency test Kappa value is 0.974 5. The stratified analysis of positive samples with different Ct values showed that the coincidence rate within each stratum was greater than 95%. Conclusion This COVID-19 antigen test kit with excellent detection performance, fast detection speed, and portable operation. It can be used as a supplementary method for existing nucleic acid detection methods for early screening of new coronavirus.

Performance Evaluation of Four Qualitative RT-PCR Assays for the Detection of Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2).

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), emerged in late 2019, and its rapid spread around the globe led the World Health Organization to declare it a pandemic. Laboratory diagnostics provide important information to help control virus transmission, and molecular nucleic acid amplification tests have been recognized as the gold standard for the direct detection of viral genetic material. The main aim of this study was to independently evaluate the analytical performance of four molecular assays that were designed for the detection of SARS-CoV-2 on open testing platforms under emergency use approval, namely, the COVIWOK COVID-19 RT-PCR Meril COVID-19 One-step RT-PCR Kit, the AmoyDx Novel Coronavirus (2019-nCoV) Detection Kit, the Meril COVID-19 One-step RT-PCR Kit and the NeoPlex COVID-19 Detection Kit, as alternatives to the current standard of care (SOC) assays in-country. All of the evaluated assays showed an acceptable performance, with a specificity of 100% and a sensitivity of 93.8% to 98.4%, compared to a SOC assay, with a Cohen's kappa coefficient of ≥0.9 (95% CI). In addition, the assays detected the AccuPlex reference material at 100 copies/mL, suggesting a good limit of detection. These assays provide suitable alternatives to the SOC assays that are currently available in-country, and these alternatives are acceptable for diagnostic use in South Africa. IMPORTANCE Laboratory diagnosis plays an important role in curbing the transmission of infection and reducing harmful delays in clinical and public health responses. Alternatives to the current standard of care assays for SARS-CoV-2 are important in order to overcome the challenges that are associated with global demands and supply shortages. Four molecular assays for the detection of SARS-CoV-2 that were designed for open testing platforms were evaluated in this study under emergency use approval. These assays had acceptable performance and provide suitable alternatives to the current standard of care assays that are available in-country. Their compatibilities with existing in-country amplification platforms make these assays convenient to use for diagnostic testing, both locally and globally These assays were recommended to the South African Health Products Regulatory Authority (SAHPRA) for patient care in South Africa.

Direct-to-consumer laboratory testing (DTCT): challenges and implications for specialists in laboratory medicine.

In vitro diagnostics (IVD) testing is a powerful tool for medical diagnosis, and patients' safety is guaranteed by a complex system of personnel qualification of the specialist in laboratory medicine, of process control, and legal restrictions in healthcare, most of them under national regulation. Direct-to-consumer laboratory testing (DTCT) is testing ordered by the consumer and performed either by the consumer at home or analysis of self-collected samples in a laboratory. However, since DTCT are not always subject to effective competent authority oversight, DTCT may pose risks to lay persons using and relying on it for healthcare decision-making. Laboratory medicine specialists should be very cautious when new DTCTs are introduced. As qualified professionals, they should feel obliged to warn and educate patients and the public about the risks of inappropriate and harmful DTCT.

Direct-to-consumer testing - benefits for consumers, people with disease and public health.

Direct-to-consumer (DTC) tests can be defined as any in-vitro diagnostic (IVD) test or, more broadly, any medical test using an IVD or medical device, that is marketed directly to consumers without involvement of a health care provider (HCP). Examples are pregnancy tests, alcohol breath tests, blood pressure measurements (medical device), coagulation tests (INR), self-monitoring of blood glucose, continuous glucose monitoring (medical device), HIV tests, HPV tests, SARS-CoV-2 antigen tests, or genetic tests. DTC tests fulfil various customer needs such as making rapid decisions (e.g. glucose monitoring for insulin dosing, SARS-CoV-2 antigen test, hormone test identifying fertile days, alcohol test), monitoring chronic conditions between consultations (e.g. diabetes, lipidaemia, hypertension), saving time and reducing consultations (e.g. INR, SARS-CoV-2 antigen test, blood pressure monitoring), screening for disease when no symptoms are present (e.g. occult blood, cholesterol, triglycerides, SARS-CoV2 antigen test), or maintaining privacy (e.g. pregnancy test, HIV test, HPV test, certain genetic tests). Further, DTC tests can reduce cost and expand access to care in countries with limited resources and can support healthcare systems in extraordinary circumstances such as a pandemic. Valid concerns about DTC testing need to be described, addressed and resolved with the help of authorities and regulators in collaboration with HCP and should not detract from the advantages DTC tests can provide. HCP should play a more prominent role in educating the public through mass media and social media on the proper use of DTC tests and help to pinpoint problem areas.

In vitro diagnostics industry in china: Current status and development strategies

In vitro diagnostics plays an important role in the process of disease diagnosis and treatment, which is referred to as the doctor's eye. In the context of the unprecedented increase in people's attention to life and health caused by the COVID-19 pandemic, in vitro diagnostics has showed an explosive growth as an important part of the health industry. For the field of in vitro diagnostics, the developing status of the world and China was summarized. Particularly, the market situation, competition landscape, and national-made situation were analyzed. The problems in the current stage of in-vitro diagnostics industry in China were analyzed, and then the corresponding suggestions and countermeasures were put forward from some aspects, including making a breakthrough in original innovation, strengthening the guarantee of funds, building a complete industrial chain, and strengthening personnel training. © 2022, China Biotechnology Press. All rights reserved.

In Vitro Diagnostic Assay to Detect SARS-CoV-2-Neutralizing Antibody in Patient Sera Using Engineered ACE-2 Mini-Protein.

The recent development and mass administration of Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) vaccines allowed for disease control, reducing hospitalizations and mortality. Most of these vaccines target the SARS-CoV-2 Spike (S) protein antigens, culminating with the production of neutralizing antibodies (NAbs) that disrupt the attachment of the virus to ACE2 receptors on the host cells. However, several studies demonstrated that the NAbs typically rise within a few weeks after vaccination but quickly reduce months later. Thus, multiple booster administration is recommended, leading to vaccination hesitancy in many populations. Detecting serum anti-SARS-CoV-2 NAbs can instruct patients and healthcare providers on correct booster strategies. Several in vitro diagnostics kits are available; however, their high cost impairs the mass NAbs diagnostic testing. Recently, we engineered an ACE2 mimetic that interacts with the Receptor Binding Domain (RBD) of the SARS-2 S protein. Here we present the use of this engineered mini-protein (p-deface2 mut) to develop a detection assay to measure NAbs in patient sera using a competitive ELISA assay. Serum samples from twenty-one patients were tested. Nine samples (42.8%) tested positive, and twelve (57.1%) tested negative for neutralizing sera. The data correlated with the result from the standard commercial assay that uses human ACE2 protein. This confirmed that p-deface2 mut could replace human ACE2 in ELISA assays. Using bacterially expressed p-deface2 mut protein is cost-effective and may allow mass SARS-CoV-2 NAbs detection, especially in low-income countries where economical diagnostic testing is crucial. Such information will help providers decide when a booster is required, reducing risks of reinfection and preventing the administration before it is medically necessary.

Smart Diagnostics: Combining Artificial Intelligence and In Vitro Diagnostics.

We are beginning a new era of Smart Diagnostics-integrated biosensors powered by recent innovations in embedded electronics, cloud computing, and artificial intelligence (AI). Universal and AI-based in vitro diagnostics (IVDs) have the potential to exponentially improve healthcare decision making in the coming years. This perspective covers current trends and challenges in translating Smart Diagnostics. We identify essential elements of Smart Diagnostics platforms through the lens of a clinically validated platform for digitizing biology and its ability to learn disease signatures. This platform for biochemical analyses uses a compact instrument to perform multiclass and multiplex measurements using fully integrated microfluidic cartridges compatible with the point of care. Image analysis digitizes biology by transforming fluorescence signals into inputs for learning disease/health signatures. The result is an intuitive Score reported to the patients and/or providers. This AI-linked universal diagnostic system has been validated through a series of large clinical studies and used to identify signatures for early disease detection and disease severity in several applications, including cardiovascular diseases, COVID-19, and oral cancer. The utility of this Smart Diagnostics platform may extend to multiple cell-based oncology tests via cross-reactive biomarkers spanning oral, colorectal, lung, bladder, esophageal, and cervical cancers, and is well-positioned to improve patient care, management, and outcomes through deployment of this resilient and scalable technology. Lastly, we provide a future perspective on the direction and trajectory of Smart Diagnostics and the transformative effects they will have on health care.

Rapid Antigen Diagnostics as Frontline Testing in the COVID-19 Pandemic.

The ongoing global COVID-19 pandemic, caused by the SARS-CoV-2 virus, has resulted in significant loss of life since December 2019. Timely and precise virus detection has been proven as an effective solution to reduce the spread of the virus and to track the epidemic. Rapid antigen diagnostics has played a significant role in the frontline of COVID-19 testing because of its convenience, low cost, and high accuracy. Herein, different types of recently innovated in-lab and commercial antigen diagnostic technologies with emphasis on the strengths and limitations of these technologies including the limit of detection, sensitivity, specificity, affordability, and usability are systematically reviewed. The perspectives of assay development are looked into.

A Method for Variant Agnostic Detection of SARS-CoV-2, Rapid Monitoring of Circulating Variants, and Early Detection of Emergent Variants Such as Omicron.

The rapid emergence of SARS-CoV-2 variants raised public health questions concerning the capability of diagnostic tests to detect new strains, the efficacy of vaccines, and how to map the geographical distribution of variants to understand transmission patterns and loads on healthcare resources. Next-generation sequencing (NGS) is the primary method for detecting and tracing new variants, but it is expensive, and it can take weeks before sequence data are available in public repositories. This article describes a customizable reverse transcription PCR (RT-PCR)-based genotyping approach which is significantly less expensive, accelerates reporting, and can be implemented in any lab that performs RT-PCR. Specific single-nucleotide polymorphisms (SNPs) and indels were identified which had high positive-percent agreement (PPA) and negative-percent agreement (NPA) compared to NGS for the major genotypes that circulated through September 11, 2021. Using a 48-marker panel, testing on 1,031 retrospective SARS-CoV-2 positive samples yielded a PPA and NPA ranging from 96.3 to 100% and 99.2 to 100%, respectively, for the top 10 most prevalent World Health Organization (WHO) lineages during that time. The effect of reducing the quantity of panel markers was explored, and a 16-marker panel was determined to be nearly as effective as the 48-marker panel at lineage assignment. Responding to the emergence of Omicron, a genotyping panel was developed which distinguishes Delta and Omicron using four highly specific SNPs. The results demonstrate the utility of the condensed panel to rapidly track the growing prevalence of Omicron across the US in December 2021 and January 2022.

Comparison of Two Different Commercial SARS-CoV-2 PCR Diagnostic Kits

Introduction: In our country RT-PCR is the only method used to diagnose COVID-19 infection, caused by SARS-CoV-2, one of the greatest epidemic in world history. In this study we aimed to compare two most frequently used commercial diagnostic kits. Materials and Methods: A total of 100 samples which were referred to our laboratory were used in this study. These nucleic acid samples were diagnosed as positive (50) or negative (50) by Coronex (R) COVID-19 (Ver.2.0) Multipleks RT-qPCR Diagnosis Kit (DS Bio and Nano Technology, Ankara, Turkey) and kept at -20 degrees C. The samples were cross checked with RealStar (R) SARS-CoV-2 RT-PCR Kit 1.0 (Altona Diagnostic, Hamburg, Germany). Extraction of the samples was performed by QlAsymphony (Qiagen, Hollanda). Data was evaluated with kappa analysis and t test. Results: All of the 50 positive samples were positive with Real Star (R) as well. Two of the negative samples were found positive when studied with Real Star (R) . There was a high concordance between the two kits (Kappa= 0.96). Mean Ct values were found as 24.1 +/- 4.9 and 19.6 +/- 4.2 for Real Stat (R) and Coronex (R), respectively. The Ct value was found less than 20 in 51.9% of the 52 positive samples studied with Real Star (R). Conclusion: There is a high concordance between the two commercial kits. Both kits may be used with confidence in symptomatic patients for the diagnosis of COVID-19.

RADx Variant Task Force Program for Assessing the Impact of Variants on SARS-CoV-2 Molecular and Antigen Tests.

Goal: Monitoring the genetic diversity and emerging mutations of SARS-CoV-2 is crucial for understanding the evolution of the virus and assuring the performance of diagnostic tests, vaccines, and therapies against COVID-19. SARS-CoV-2 is still adapting to humans and, as illustrated by B.1.1.7 (Alpha) and B.1.617.2 (Delta), lineage dynamics are fluid, and strain prevalence may change radically in a matter of months. The National Institutes of Health's Rapid Acceleration of Diagnostics (RADxSM) initiative created a Variant Task Force to assess the impact of emerging SARS-CoV-2 variants on in vitro diagnostic testing. Working in tandem with clinical laboratories, the FDA, and the CDC, the Variant Task Force uses both in silico modeling and in vitro testing to determine the effect of SARS-CoV-2 mutations on diagnostic molecular and antigen tests. Here, we offer an overview of the approach and activities of the RADx Variant Task Force to ensure test performance against emerging SARS-CoV-2 lineages.

Learning from past pandemic governance: Early response and Public-Private Partnerships in testing of COVID-19 in South Korea.

How can political elites learn from the past to enhance sustainability of their leadership in a pandemic situation? In this article, we develop a theoretical framework of policy implementation that combines collaboration from public and private sectors ("Public-Private Partnership," or PPP) to efficiently deal with urgent crises such as COVID-19. We explain the role of new institutions prompted by policy failure precedence (Time 1) that at a later time period (Time 2) allow for the activation of PPPs with the aim to extend the political life of incumbent leaderships. Specifically, we examine the case of South Korea, a country in which a prior case of MERS in 2015 (Time 1) had established new policies for pandemic governance. In 2020, such policies were activated by the incumbent leadership in order to contain COVID-19 (Time 2). In particular, for swift and effective management of the pandemic, the South Korean government utilized partnerships with the private sector to exponentially increase the amount of Real-Time Polymerase Chain Reaction (RT-PCR) testing. We apply Policy Feedback Theory to demonstrate the political effects of failed policy precedents and how the political outcomes again shape new policies in a dynamic and cyclical manner. Empirically, we conduct a content analysis of South Korea's pharmaceutical sector in government procurement and exports of test-kits during the COVID-19 pandemic. We show that as the pandemic situation progressed, South Korea's leader, who had been in danger of plummeting support to the extent that impeachment was discussed as a viable option, drastically shifted public opinion to achieve a landslide victory in general elections in April 2020. Our findings suggest that democratic governments, aware of precedents and wary of their fate in elections, are pressured to perform well in crisis management, and thus turn to rapidly mobilizing public and private means for survival. Such means are evidenced by the case of emergency use authorization (EUA) process for test-kits, in which "leapfrogging players" - up-and-coming innovators - that contribute to turning a pandemic crisis into an opportunity for sustainable leadership and for themselves.

Dye-Loaded Polymersome-Based Lateral Flow Assay: Rational Design of a COVID-19 Testing Platform by Repurposing SARS-CoV-2 Antibody Cocktail and Antigens Obtained from Positive Human Samples.

The global pandemic of COVID-19 continues to be an important threat, especially with the fast transmission rate observed after the discovery of novel mutations. In this perspective, prompt diagnosis requires massive economical and human resources to mitigate the disease. The current study proposes a rational design of a colorimetric lateral flow immunoassay (LFA) based on the repurposing of human samples to produce COVID-19-specific antigens and antibodies in combination with a novel dye-loaded polymersome for naked-eye detection. A group of 121 human samples (61 serums and 60 nasal swabs) were obtained and analyzed by RT-PCR and ELISA. Pooled samples were used to purify antibodies using affinity chromatography, while antigens were purified via magnetic nanoparticles-based affinity. The purified proteins were confirmed for their specificity to COVID-19 via commercial LFA, ELISA, and electrochemical tests in addition to sodium dodecyl sulfate-polyacrylamide gel electrophoresis analysis. Polymersomes were prepared using methoxy polyethylene glycol-b-polycaprolactone (mPEG-b-PCL) diblock copolymers and loaded with a Coomassie Blue dye. The polymersomes were then functionalized with the purified antibodies and applied for the preparation of two types of LFA (antigen test and antibody test). Overall, the proposed diagnostic tests demonstrated 93 and 92.2% sensitivity for antigen and antibody tests, respectively. The repeatability (92-94%) and reproducibility (96-98%) of the tests highlight the potential of the proposed LFA. The LFA test was also analyzed for stability, and after 4 weeks, 91-97% correct diagnosis was observed. The current LFA platform is a valuable assay that has great economical and analytical potential for widespread applications.

Analysis of external quality assessment samples revealed crucial performance differences between commercial RT-PCR assays for SARS-CoV-2 detection when taking extraction methods and real-time-PCR instruments into account.

In limelight of the ongoing pandemic SARS-CoV-2 testing is critical for the diagnosis of infected patients, contact-tracing and mitigating the transmission. Diagnostic laboratories are expected to provide appropriate testing with maximum accuracy. Real-time reverse transcriptase PCR (RT-PCR) is the diagnostic standard. However, only a handful of studies have reviewed their performance in clinical settings. The aim of this study was to compare the performance of the overall analytical matrix including the extraction kit (BD MAX, Promega, Qiagen), the PCR instrument (Agilent Mx3005 P, BD MAX, Qiagen Rotor-Gene, Roche Cobas z 480) and the RT-PCR assay (Altona Diagnostics, CerTest Biotec, R-Biopharm AG) using predefined samples from proficiency testing organizers. The greatest difference of the cycle threshold values between the matrices was nine cycles. One borderline sample could not be detected by three out of twelve analytical matrices and yielded a false negative result. We therefore conclude that diagnostic laboratories should take the complete analytical matrix in addition to the performance values published by the manufacturer for a respective RT-PCR kit into account. With limited resources laboratories have to validate a wide range of kits to determine appropriate analytical matrices for detecting SARS-CoV-2 reliably. The interpretation of clinical results has to be adapted accordingly.

The Clinical Review Committee: Impact of the Development of In Vitro Diagnostic Tests for SARS-CoV-2 Within RADx Tech.

The NIH Rapid Acceleration of Diagnostics (RADxSM) Tech Program was created to speed the development, validation, and commercialization of innovative point-of-care (POC) and home-based tests, and to improve clinical laboratory tests, that can directly detect SARS-CoV-2. Leveraging the experience of the Point-of-Care Technologies Research Network, a Clinical Review Committee (CRC) composed of clinicians, bioengineers, regulatory experts, and laboratorians was created to provide structured feedback to SARS-CoV-2 diagnostic innovators. The CRC convened 53 meetings with 49 companies offering SARS-CoV-2 tests in POC and reference laboratory formats as well as collection materials. The CRC identified common barriers to device design finalization including biosafety, workflow, result reporting, regulatory requirements, sample type, supply chain, limit of detection, lack of relevant validation data, and price-performance-use mismatch. Feedback from companies participating was positive.

Effective screening strategies for detection of asymptomatic COVID-19 travelers at airport quarantine stations: Exploratory findings in Japan.

The quantitative reverse transcription polymerase chain reaction method using nasopharyngeal swabs (NPS RT-qPCR) is regarded as the reference standard for diagnosing coronavirus disease 2019 (COVID-19). However, when using NPS RT-qPCR at busy airport quarantine stations, there are constraints on testing capacity, time, travelerstolerance, and availability of personal protective equipment for quarantine officers. A feasible alternative is therefore needed to test incoming travelers, especially when passenger numbers increase with the resumption of business, tourism, and economic activities. To explore alternatives to NPS RT-qPCR, we collected nasopharyngeal, anterior nasal, and saliva samples chronologically over days 1-7 from asymptomatic COVID-19 air travelers who were under quarantine at a designated facility, and we then compared test results for 9 different methods, comprising RT-qPCR (including the reference method), loop-mediated isothermal amplification (LAMP), and qualitative and quantitative antigen testing. We evaluated sensitivity for 97 person-day samples independently to evaluate asymptomatic travelers regardless of their testing date and period of asymptomatic status upon entry. Sensitivity of the different tests varied from 46.6% to 81.0%, but this was improved from 72.7% to 100.0% when the viral load was > 10 4 copies/sample on NPS RT-qPCR. Thus, most high-risk asymptomatic travelers with higher viral load would be detected by the tests evaluated. Quantitative antigen testing using saliva samples showed 90.9% sensitivity and provided quicker results, and should be an acceptable alternative to NPS RT-qPCR at busy airport quarantine stations. We discuss the implications of our exploratory findings for establishing a comprehensive and feasible testing strategy for COVID-19 among air passengers.

Multiplex quantitative detection of SARS-CoV-2 specific IgG and IgM antibodies based on DNA-assisted nanopore sensing.

The coronavirus disease (COVID-19) caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has spread into a global pandemic. Early and accurate diagnosis and quarantine remain the most effective mitigation strategy. Although reverse transcriptase polymerase chain reaction (RT-qPCR) is the gold standard for COVID-19 diagnosis, recent studies suggest that nucleic acids were undetectable in a significant number of cases with clinical features of COVID-19. Serologic assays that detect human antibodies to SARS-CoV-2 serve as a complementary method to diagnose these cases, as well as to identify asymptomatic cases and qualified convalescent serum donors. However, commercially available enzyme-linked immunosorbent assays (ELISA) are laborious and non-quantitative, while point-of-care assays suffer from low detection accuracy. To provide a serologic assay with high performance and portability for potential point-of-care applications, we developed DNA-assisted nanopore sensing for quantification of SARS-CoV-2 related antibodies in human serum. Different DNA structures were used as detection reporters for multiplex quantification of immunoglobulin M (IgM) and immunoglobulin G (IgG) antibodies against the nucleocapsid protein of SARS-CoV-2 in serum specimens from patients with conformed or suspected infection. Comparing to a clinically used point-of-care assay and an ELISA assay, our technology can reliably quantify SARS-CoV-2 antibodies with higher accuracy, large dynamic range, and potential for assay automation.