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1.
Sensors (Basel) ; 22(1)2021 Dec 29.
Article in English | MEDLINE | ID: covidwho-1615852

ABSTRACT

Infrared thermographs (IRTs) implemented according to standardized best practices have shown strong potential for detecting elevated body temperatures (EBT), which may be useful in clinical settings and during infectious disease epidemics. However, optimal IRT calibration methods have not been established and the clinical performance of these devices relative to the more common non-contact infrared thermometers (NCITs) remains unclear. In addition to confirming the findings of our preliminary analysis of clinical study results, the primary intent of this study was to compare methods for IRT calibration and identify best practices for assessing the performance of IRTs intended to detect EBT. A key secondary aim was to compare IRT clinical accuracy to that of NCITs. We performed a clinical thermographic imaging study of more than 1000 subjects, acquiring temperature data from several facial locations that, along with reference oral temperatures, were used to calibrate two IRT systems based on seven different regression methods. Oral temperatures imputed from facial data were used to evaluate IRT clinical accuracy based on metrics such as clinical bias (Δcb), repeatability, root-mean-square difference, and sensitivity/specificity. We proposed several calibration approaches designed to account for the non-uniform data density across the temperature range and a constant offset approach tended to show better ability to detect EBT. As in our prior study, inner canthi or full-face maximum temperatures provided the highest clinical accuracy. With an optimal calibration approach, these methods achieved a Δcb between ±0.03 °C with standard deviation (σΔcb) less than 0.3 °C, and sensitivity/specificity between 84% and 94%. Results of forehead-center measurements with NCITs or IRTs indicated reduced performance. An analysis of the complete clinical data set confirms the essential findings of our preliminary evaluation, with minor differences. Our findings provide novel insights into methods and metrics for the clinical accuracy assessment of IRTs. Furthermore, our results indicate that calibration approaches providing the highest clinical accuracy in the 37-38.5 °C range may be most effective for measuring EBT. While device performance depends on many factors, IRTs can provide superior performance to NCITs.


Subject(s)
Body Temperature , Thermography , Calibration , Fever , Humans , Infrared Rays , Thermometers
2.
Sci Rep ; 11(1): 20595, 2021 10 18.
Article in English | MEDLINE | ID: covidwho-1475487

ABSTRACT

The delivery of safe, visible wavelengths of light can be an effective, pathogen-agnostic, countermeasure that would expand the current portfolio of SARS-CoV-2 intervention strategies beyond the conventional approaches of vaccine, antibody, and antiviral therapeutics. Employing custom biological light units, that incorporate optically engineered light-emitting diode (LED) arrays, we harnessed monochromatic wavelengths of light for uniform delivery across biological surfaces. We demonstrated that primary 3D human tracheal/bronchial-derived epithelial tissues tolerated high doses of a narrow spectral band of visible light centered at a peak wavelength of 425 nm. We extended these studies to Vero E6 cells to understand how light may influence the viability of a mammalian cell line conventionally used for assaying SARS-CoV-2. The exposure of single-cell monolayers of Vero E6 cells to similar doses of 425 nm blue light resulted in viabilities that were dependent on dose and cell density. Doses of 425 nm blue light that are well-tolerated by Vero E6 cells also inhibited infection and replication of cell-associated SARS-CoV-2 by > 99% 24 h post-infection after a single five-minute light exposure. Moreover, the 425 nm blue light inactivated cell-free betacoronaviruses including SARS-CoV-1, MERS-CoV, and SARS-CoV-2 up to 99.99% in a dose-dependent manner. Importantly, clinically applicable doses of 425 nm blue light dramatically inhibited SARS-CoV-2 infection and replication in primary human 3D tracheal/bronchial tissue. Safe doses of visible light should be considered part of the strategic portfolio for the development of SARS-CoV-2 therapeutic countermeasures to mitigate coronavirus disease 2019 (COVID-19).


Subject(s)
COVID-19/drug therapy , COVID-19/prevention & control , Light , SARS-CoV-2 , Trachea/radiation effects , Virus Replication/radiation effects , Adult , Animals , Antiviral Agents/pharmacology , Bronchi , Calibration , Cell-Free System , Chlorocebus aethiops , Epithelium/pathology , Female , Humans , Respiratory Mucosa/radiation effects , Trachea/virology , Vero Cells
3.
Sci Rep ; 11(1): 20728, 2021 10 20.
Article in English | MEDLINE | ID: covidwho-1475481

ABSTRACT

The impact of the extent of testing infectious individuals on suppression of COVID-19 is illustrated from the early stages of outbreaks in Germany, the Hubei province of China, Italy, Spain and the UK. The predicted percentage of untested infected individuals depends on the specific outbreak but we found that they typically represent 60-80% of all infected individuals during the early stages of the outbreaks. We propose that reducing the underlying transmission from untested cases is crucial to suppress the virus. This can be achieved through enhanced testing in combination with social distancing and other interventions that reduce transmission such as wearing face masks. Once transmission from silent carriers is kept under control by these means, the virus could have been fully suppressed through fast isolation and contact tracing of tested cases.


Subject(s)
COVID-19 Testing/methods , COVID-19/diagnosis , COVID-19/virology , Contact Tracing/methods , Masks , SARS-CoV-2 , Basic Reproduction Number , COVID-19/prevention & control , Calibration , China/epidemiology , Disease Outbreaks , Germany/epidemiology , Humans , Italy/epidemiology , Models, Theoretical , Physical Distancing , Poisson Distribution , Spain/epidemiology , United Kingdom/epidemiology
4.
PLoS One ; 16(9): e0257613, 2021.
Article in English | MEDLINE | ID: covidwho-1430545

ABSTRACT

This paper analyses COVID-19 patients' dynamics during the first wave in the region of Castilla y León (Spain) with around 2.4 million inhabitants using multi-state competing risk survival models. From the date registered as the start of the clinical process, it is assumed that a patient can progress through three intermediate states until reaching an absorbing state of recovery or death. Demographic characteristics, epidemiological factors such as the time of infection and previous vaccinations, clinical history, complications during the course of the disease and drug therapy for hospitalised patients are considered as candidate predictors. Regarding risk factors associated with mortality and severity, consistent results with many other studies have been found, such as older age, being male, and chronic diseases. Specifically, the hospitalisation (death) rate for those over 69 is 27.2% (19.8%) versus 5.3% (0.7%) for those under 70, and for males is 14.5%(7%) versus 8.3%(4.6%)for females. Among patients with chronic diseases the highest rates of hospitalisation are 26.1% for diabetes and 26.3% for kidney disease, while the highest death rate is 21.9% for cerebrovascular disease. Moreover, specific predictors for different transitions are given, and estimates of the probability of recovery and death for each patient are provided by the model. Some interesting results obtained are that for patients infected at the end of the period the hazard of transition from hospitalisation to ICU is significatively lower (p < 0.001) and the hazard of transition from hospitalisation to recovery is higher (p < 0.001). For patients previously vaccinated against pneumococcus the hazard of transition to recovery is higher (p < 0.001). Finally, internal validation and calibration of the model are also performed.


Subject(s)
COVID-19/diagnosis , COVID-19/mortality , Disease Progression , Hospital Records , Hospitals , Primary Health Care , Adolescent , Adult , Aged , Aged, 80 and over , COVID-19/complications , COVID-19/drug therapy , Calibration , Child , Child, Preschool , Comorbidity , Confidence Intervals , Female , Humans , Infant , Infant, Newborn , Male , Middle Aged , Probability , Proportional Hazards Models , Reproducibility of Results , Spain/epidemiology , Young Adult
5.
Sensors (Basel) ; 21(17)2021 Sep 02.
Article in English | MEDLINE | ID: covidwho-1390739

ABSTRACT

Social distancing protocols have been highly recommended by the World Health Organization (WHO) to curb the spread of COVID-19. However, one major challenge to enforcing social distancing in public areas is how to perceive people in three dimensions. This paper proposes an innovative pedestrian 3D localization method using monocular images combined with terrestrial point clouds. In the proposed approach, camera calibration is achieved based on the correspondences between 2D image points and 3D world points. The vertical coordinates of the ground plane where pedestrians stand are extracted from the point clouds. Then, using the assumption that the pedestrian is always perpendicular to the ground, the 3D coordinates of the pedestrian's feet and head are calculated iteratively using collinear equations. This allows the three-dimensional localization and height determination of pedestrians using monocular cameras, which are widely distributed in many major cities. The performance of the proposed method was evaluated using two different datasets. Experimental results show that the pedestrian localization error of the proposed approach was less than one meter within tens of meters and performed better than other localization techniques. The proposed approach uses simple and efficient calculations, obtains accurate location, and can be used to implement social distancing rules. Moreover, since the proposed approach also generates accurate height values, exclusionary schemes to social distancing protocols, particularly the parent-child exemption, can be introduced in the framework.


Subject(s)
COVID-19 , Pedestrians , Calibration , Foot , Humans , SARS-CoV-2
6.
Nat Commun ; 12(1): 4586, 2021 07 28.
Article in English | MEDLINE | ID: covidwho-1387355

ABSTRACT

Heterogeneous immunoassays such as ELISA have become indispensable in modern bioanalysis, yet translation into point-of-care assays is hindered by their dependence on external calibration and multiple washing and incubation steps. Here, we introduce RAPPID (Ratiometric Plug-and-Play Immunodiagnostics), a mix-and-measure homogeneous immunoassay platform that combines highly specific antibody-based detection with a ratiometric bioluminescent readout. The concept entails analyte-induced complementation of split NanoLuc luciferase fragments, photoconjugated to an antibody sandwich pair via protein G adapters. Introduction of a calibrator luciferase provides a robust ratiometric signal that allows direct in-sample calibration and quantitative measurements in complex media such as blood plasma. We developed RAPPID sensors that allow low-picomolar detection of several protein biomarkers, anti-drug antibodies, therapeutic antibodies, and both SARS-CoV-2 spike protein and anti-SARS-CoV-2 antibodies. With its easy-to-implement standardized workflow, RAPPID provides an attractive, fast, and low-cost alternative to traditional immunoassays, in an academic setting, in clinical laboratories, and for point-of-care applications.


Subject(s)
Antibodies, Viral/blood , COVID-19 Serological Testing/methods , COVID-19/diagnosis , Immunoassay/standards , Luminescent Measurements/standards , SARS-CoV-2/immunology , Spike Glycoprotein, Coronavirus/blood , COVID-19/immunology , COVID-19/virology , COVID-19 Serological Testing/instrumentation , Calibration , GTP-Binding Proteins/chemistry , Genes, Reporter , Humans , Immunoconjugates/chemistry , Limit of Detection , Luciferases/genetics , Luciferases/metabolism , Point-of-Care Testing , SARS-CoV-2/genetics
7.
J Appl Clin Med Phys ; 21(12): 325-328, 2020 Dec.
Article in English | MEDLINE | ID: covidwho-1384081

ABSTRACT

PURPOSE: To investigate the feasibility and practicality of ultraviolet (UV) germicidal irradiation of the inner bore of a computed tomography (CT) gantry as a means of viral decontamination. METHOD: A UV lamp (PADNUT 38 W, 253 nm UV-C light tube) and UV-C dosimeter (GENERAL UV-C Digital Light Meter No. UV512C) were used to measure irradiance throughout the inner bore of a CT scanner gantry. Irradiance (units µW/cm2 ) was related to the time required to achieve 6-log viral kill (10-6 survival fraction). RESULTS: A warm-up time of ~120 s was required for the lamp to reach stable irradiance. Irradiance at the scan plane (z = 0 cm) of the CT scanner was 580.9 µW/cm2 , reducing to ~350 µW/cm2 at z = ±20 cm toward the front or back of the gantry. The angular distribution of irradiation was uniform within 10% coefficient of variation. A conservative estimate suggests at least 6-log kill (survival fraction ≤ 10-6 ) of viral RNA within ±20 cm of the scan plane with an irradiation time of 120 s from cold start. More conservatively, running the lamp for 180 s (3 min) or 300 s (5 min) from cold start is estimated to yield survival fraction <<10-7 survival fraction within ±20 cm of the scan plane. CONCLUSION: Ultraviolet irradiation of the inner bore of the CT gantry can be achieved with a simple UV-C lamp attached to the CT couch. Such practice could augment manual wipe-down procedures, improve safety for CT technologists or housekeeping staff, and could potentially reduce turnover time between scanning sessions.


Subject(s)
COVID-19/prevention & control , Disinfection/methods , Infection Control/methods , Tomography Scanners, X-Ray Computed , Tomography, X-Ray Computed/instrumentation , Calibration , Decontamination/instrumentation , Diagnostic Imaging/methods , Infection Control/instrumentation , RNA, Viral/radiation effects , Radiometry , SARS-CoV-2/radiation effects , Ultraviolet Rays
8.
Nature ; 598(7880): 338-341, 2021 10.
Article in English | MEDLINE | ID: covidwho-1373441

ABSTRACT

The COVID-19 pandemic disrupted health systems and economies throughout the world during 2020 and was particularly devastating for the United States, which experienced the highest numbers of reported cases and deaths during 20201-3. Many of the epidemiological features responsible for observed rates of morbidity and mortality have been reported4-8; however, the overall burden and characteristics of COVID-19 in the United States have not been comprehensively quantified. Here we use a data-driven model-inference approach to simulate the pandemic at county-scale in the United States during 2020 and estimate critical, time-varying epidemiological properties underpinning the dynamics of the virus. The pandemic in the United States during 2020 was characterized by national ascertainment rates that increased from 11.3% (95% credible interval (CI): 8.3-15.9%) in March to 24.5% (18.6-32.3%) during December. Population susceptibility at the end of the year was 69.0% (63.6-75.4%), indicating that about one third of the US population had been infected. Community infectious rates, the percentage of people harbouring a contagious infection, increased above 0.8% (0.6-1.0%) before the end of the year, and were as high as 2.4% in some major metropolitan areas. By contrast, the infection fatality rate fell to 0.3% by year's end.


Subject(s)
COVID-19/epidemiology , COVID-19/transmission , SARS-CoV-2 , Basic Reproduction Number , COVID-19/economics , COVID-19/mortality , Calibration , Cost of Illness , Humans , Incidence , Pandemics , Prevalence , United States/epidemiology
9.
Mol Diagn Ther ; 25(5): 617-628, 2021 09.
Article in English | MEDLINE | ID: covidwho-1328680

ABSTRACT

BACKGROUND AND OBJECTIVE: Since the initial coronavirus disease outbreak in late 2019 (COVID-19), reverse-transcription real-time polymerase chain reaction (RT-qPCR) has become the gold standard test to detect severe acute respiratory syndrome-related coronavirus 2 (SARS-CoV-2). However, a more sensitive and accurate diagnostic tool was required. Therefore, droplet digital polymerase chain reaction (ddPCR) was suggested as an alternative method. Here, we evaluated the performance of ddPCR to detect SARS-CoV-2 and compared it to the performance of RT-qPCR. METHODS: The analytical performances, including limit of blank and limit of detection, were established using positive and negative SARS-CoV-2 reference materials. A total of 366 RNA extracts (173 positive and 193 negative by RT-qPCR) were collected from four institutions and tested with a Bio-Rad SARS-CoV-2 ddPCR kit that detects the SARS-CoV-2 genome using primers for N1 and N2. RESULTS: Limit of blank was set at 0, and the limits of detection of N1 and N2 were 1.99 copies/µL and 5.18 copies/µL, respectively. Linearity was evaluated using serial dilution samples, which demonstrated good results (R2: 0.999, linear range: 5.88-6825.25 copies/µL for N1 and R2: 0.999, 5.53-5855.47 copies/µL for N2). The results of ddPCR and RT-qPCR revealed substantial agreement (Cohen's kappa: 0.639, p < 0.01). The 63 samples with positive ddPCR but negative RT-qPCR showed low copy numbers, and 55% of them had COVID-19-related symptoms. CONCLUSIONS: Droplet digital polymerase chain reaction demonstrated excellent sensitivity for SARS-Cov-2 detection and consistently agreed with the results from conventional RT-qPCR. Furthermore, ddPCR provided quantitative data that can be used to monitor changes in the viral load of patients with COVID-19.


Subject(s)
COVID-19 Nucleic Acid Testing/methods , COVID-19/diagnosis , RNA, Viral/genetics , SARS-CoV-2/genetics , COVID-19/virology , COVID-19 Nucleic Acid Testing/standards , Calibration , Humans , Limit of Detection , Nasopharynx/virology , Reference Values
10.
Molecules ; 26(13)2021 Jun 22.
Article in English | MEDLINE | ID: covidwho-1288957

ABSTRACT

In the current work, a simple, economical, accurate, and precise HPLC method with UV detection was developed to quantify Favipiravir (FVIR) in spiked human plasma using acyclovir (ACVR) as an internal standard in the COVID-19 pandemic time. Both FVIR and ACVR were well separated and resolved on the C18 column using the mobile phase blend of methanol:acetonitrile:20 mM phosphate buffer (pH 3.1) in an isocratic mode flow rate of 1 mL/min with a proportion of 30:10:60 %, v/v/v. The detector wavelength was set at 242 nm. Maximum recovery of FVIR and ACVR from plasma was obtained with dichloromethane (DCM) as extracting solvent. The calibration curve was found to be linear in the range of 3.1-60.0 µg/mL with regression coefficient (r2) = 0.9976. However, with acceptable r2, the calibration data's heteroscedasticity was observed, which was further reduced using weighted linear regression with weighting factor 1/x. Finally, the method was validated concerning sensitivity, accuracy (Inter and Intraday's % RE and RSD were 0.28, 0.65 and 1.00, 0.12 respectively), precision, recovery (89.99%, 89.09%, and 90.81% for LQC, MQC, and HQC, respectively), stability (% RSD for 30-day were 3.04 and 1.71 for LQC and HQC, respectively at -20 °C), and carry-over US-FDA guidance for Bioanalytical Method Validation for researchers in the COVID-19 pandemic crisis. Furthermore, there was no significant difference for selectivity when evaluated at LLOQ concentration of 3 µg/mL of FVIR and relative to the blank.


Subject(s)
Amides/analysis , Amides/blood , Antiviral Agents/analysis , Antiviral Agents/blood , Biological Assay/methods , COVID-19/drug therapy , Chromatography, High Pressure Liquid/methods , Liquid-Liquid Extraction/methods , Pyrazines/analysis , Pyrazines/blood , Acyclovir/analysis , Acyclovir/blood , COVID-19/blood , Calibration , Drug Stability , Freezing , Humans , Reference Standards , Reproducibility of Results , Solvents/chemistry
11.
PLoS One ; 16(6): e0252757, 2021.
Article in English | MEDLINE | ID: covidwho-1280620

ABSTRACT

BACKGROUND: A number of nucleic acid amplification tests (NAATs) for SARS-CoV-2 with different reagents have been approved for clinical use in Japan. These include research kits approved under emergency use authorization through simplified process to stabilize the supply of the reagents. Although these research kits have been increasingly used in clinical practice, limited data is available for the diagnostic performance in clinical settings. METHODS: We compared sensitivity, specificity, and cycle threshold (Ct) values obtained by NAATs using 10 kits approved in Japan including eight kits those receiving emergency use authorization using 69 frozen-stored clinical samples including 23 positive samples with various Ct values and 46 negative samples. RESULTS: Viral copy number of the frozen-stored samples determined with LightMix E-gene test ranged from 0.6 to 84521.1 copies/µL. While no false-positive results were obtained by any of these tests (specificity: 100% [95% CI, 88.9%-100%]), sensitivity of the nine tests ranged from 68.2% [95% CI, 45.1%-86.1%] to 95.5% [95% CI, 77.2%-99.9%] using LightMix E-gene test as the gold standard. All tests showed positive results for all samples with ≥100 copies/µL. Significant difference of Ct values even among tests amplifying the same genetic region (N1-CDC, N2) was also observed. CONCLUSION: Difference in the diagnostic performance was observed among NAATs approved in Japan. Regarding diagnostic kits for emerging infectious diseases, a system is needed to ensure both rapidity of reagent supply and accuracy of diagnosis. Ct values, which are sometimes regarded as a marker of infectivity, are not interchangeable when obtained by different assays.


Subject(s)
COVID-19 Nucleic Acid Testing/methods , Calibration , Coronavirus Envelope Proteins/genetics , Humans , Nucleic Acid Amplification Techniques/methods , Polymerase Chain Reaction/methods , Sensitivity and Specificity
12.
Nat Commun ; 12(1): 3674, 2021 06 16.
Article in English | MEDLINE | ID: covidwho-1275919

ABSTRACT

There is a consensus that mass vaccination against SARS-CoV-2 will ultimately end the COVID-19 pandemic. However, it is not clear when and which control measures can be relaxed during the rollout of vaccination programmes. We investigate relaxation scenarios using an age-structured transmission model that has been fitted to age-specific seroprevalence data, hospital admissions, and projected vaccination coverage for Portugal. Our analyses suggest that the pressing need to restart socioeconomic activities could lead to new pandemic waves, and that substantial control efforts prove necessary throughout 2021. Using knowledge on control measures introduced in 2020, we anticipate that relaxing measures completely or to the extent as in autumn 2020 could launch a wave starting in April 2021. Additional waves could be prevented altogether if measures are relaxed as in summer 2020 or in a step-wise manner throughout 2021. We discuss at which point the control of COVID-19 would be achieved for each scenario.


Subject(s)
COVID-19 Vaccines/therapeutic use , COVID-19/prevention & control , Communicable Disease Control/methods , Mass Vaccination , Adolescent , Adult , Age Factors , Aged , Aged, 80 and over , Basic Reproduction Number , COVID-19/transmission , Calibration , Child , Child, Preschool , Communicable Disease Control/organization & administration , Hospitalization/statistics & numerical data , Humans , Mass Vaccination/organization & administration , Mass Vaccination/statistics & numerical data , Middle Aged , Models, Theoretical , Portugal/epidemiology , Vaccination Coverage , Young Adult
15.
Immun Inflamm Dis ; 9(2): 595-607, 2021 06.
Article in English | MEDLINE | ID: covidwho-1130502

ABSTRACT

BACKGROUND: Identifying patients who may develop severe coronavirus disease 2019 (COVID-19) will facilitate personalized treatment and optimize the distribution of medical resources. METHODS: In this study, 590 COVID-19 patients during hospitalization were enrolled (Training set: n = 285; Internal validation set: n = 127; Prospective set: n = 178). After filtered by two machine learning methods in the training set, 5 out of 31 clinical features were selected into the model building to predict the risk of developing severe COVID-19 disease. Multivariate logistic regression was applied to build the prediction nomogram and validated in two different sets. Receiver operating characteristic (ROC) analysis and decision curve analysis (DCA) were used to evaluate its performance. RESULTS: From 31 potential predictors in the training set, 5 independent predictive factors were identified and included in the risk score: C-reactive protein (CRP), lactate dehydrogenase (LDH), Age, Charlson/Deyo comorbidity score (CDCS), and erythrocyte sedimentation rate (ESR). Subsequently, we generated the nomogram based on the above features for predicting severe COVID-19. In the training cohort, the area under curves (AUCs) were 0.822 (95% CI, 0.765-0.875) and the internal validation cohort was 0.762 (95% CI, 0.768-0.844). Further, we validated it in a prospective cohort with the AUCs of 0.705 (95% CI, 0.627-0.778). The internally bootstrapped calibration curve showed favorable consistency between prediction by nomogram and the actual situation. And DCA analysis also conferred high clinical net benefit. CONCLUSION: In this study, our predicting model based on five clinical characteristics of COVID-19 patients will enable clinicians to predict the potential risk of developing critical illness and thus optimize medical management.


Subject(s)
COVID-19/epidemiology , Machine Learning , Models, Theoretical , Nomograms , Pandemics , SARS-CoV-2 , Adult , Aged , Area Under Curve , Calibration , Decision Support Techniques , Female , Humans , Logistic Models , Male , Middle Aged , Prospective Studies , ROC Curve , Retrospective Studies , Risk Assessment , Risk Factors , Sensitivity and Specificity
16.
J Healthc Eng ; 2021: 6680762, 2021.
Article in English | MEDLINE | ID: covidwho-1102209

ABSTRACT

Out of all the changes to our daily life brought by the COVID-19 pandemic, one of the most significant ones has been the limited access to health services that we used to take for granted. Thus, in order to prevent temporary injuries from having lingering or permanent effects, the need for home rehabilitation device is urgent. For this reason, this paper proposes a cable-driven device for limb rehabilitation, CUBE2, with a novel end-effector (EE) design and autotuning capabilities to enable autonomous use. The proposed design is presented as an evolution of the previous CUBE design. In this paper, the proposed device is modelled and analyzed with finite element analysis. Then, a novel vision-based control strategy is described. Furthermore, a prototype has been manufactured and validated experimentally. Preliminary test to estimate home position repeatability has been carried out.


Subject(s)
Home Care Services , Telerehabilitation , Algorithms , Biomechanical Phenomena , COVID-19 , Calibration/standards , Equipment Design , Humans , Robotics/instrumentation , SARS-CoV-2 , Telerehabilitation/instrumentation , Telerehabilitation/methods , Telerehabilitation/standards
17.
ACS Appl Mater Interfaces ; 13(8): 10321-10327, 2021 Mar 03.
Article in English | MEDLINE | ID: covidwho-1087402

ABSTRACT

Early diagnosis of SARS-CoV-2 infection is critical for facilitating proper containment procedures, and a rapid, sensitive antigen assay is a critical step in curbing the pandemic. In this work, we report the use of a high-purity semiconducting (sc) single-walled carbon nanotube (SWCNT)-based field-effect transistor (FET) decorated with specific binding chemistry to assess the presence of SARS-CoV-2 antigens in clinical nasopharyngeal samples. Our SWCNT FET sensors, with functionalization of the anti-SARS-CoV-2 spike protein antibody (SAb) and anti-nucleocapsid protein antibody, detected the S antigen (SAg) and N antigen (NAg), reaching a limit of detection of 0.55 fg/mL for SAg and 0.016 fg/mL for NAg in calibration samples. SAb-functionalized FET sensors also exhibited good sensing performance in discriminating positive and negative clinical samples, indicating a proof of principle for use as a rapid COVID-19 antigen diagnostic tool with high analytical sensitivity and specificity at low cost.


Subject(s)
Antigens, Viral/analysis , Biosensing Techniques , COVID-19 Testing/instrumentation , Nanotubes, Carbon/chemistry , Semiconductors , Transistors, Electronic , COVID-19 Testing/methods , Calibration , Electrodes , Gold , Humans , Limit of Detection , Materials Testing , Microscopy, Atomic Force , Microscopy, Fluorescence , Nanotechnology , SARS-CoV-2 , Sensitivity and Specificity , Spectrophotometry, Ultraviolet , Spectroscopy, Near-Infrared , Spectrum Analysis, Raman , Spike Glycoprotein, Coronavirus/analysis
18.
Nat Commun ; 12(1): 893, 2021 02 09.
Article in English | MEDLINE | ID: covidwho-1075216

ABSTRACT

SARS-CoV-2 is transmitted primarily through close, person-to-person interactions. Physical distancing policies can control the spread of SARS-CoV-2 by reducing the amount of these interactions in a population. Here, we report results from four waves of contact surveys designed to quantify the impact of these policies during the COVID-19 pandemic in the United States. We surveyed 9,743 respondents between March 22 and September 26, 2020. We find that interpersonal contact has been dramatically reduced in the US, with an 82% (95%CI: 80%-83%) reduction in the average number of daily contacts observed during the first wave compared to pre-pandemic levels. However, we find increases in contact rates over the subsequent waves. We also find that certain demographic groups, including people under 45 and males, have significantly higher contact rates than the rest of the population. Tracking these changes can provide rapid assessments of the impact of physical distancing policies and help to identify at-risk populations.


Subject(s)
COVID-19/epidemiology , Contact Tracing , Pandemics , SARS-CoV-2/physiology , Age Factors , COVID-19/transmission , Calibration , Family Characteristics , Humans , Surveys and Questionnaires
19.
Sci Adv ; 7(1)2021 01.
Article in English | MEDLINE | ID: covidwho-1060363

ABSTRACT

The COVID-19 pandemic has created a public health crisis. Because SARS-CoV-2 can spread from individuals with presymptomatic, symptomatic, and asymptomatic infections, the reopening of societies and the control of virus spread will be facilitated by robust population screening, for which virus testing will often be central. After infection, individuals undergo a period of incubation during which viral titers are too low to detect, followed by exponential viral growth, leading to peak viral load and infectiousness and ending with declining titers and clearance. Given the pattern of viral load kinetics, we model the effectiveness of repeated population screening considering test sensitivities, frequency, and sample-to-answer reporting time. These results demonstrate that effective screening depends largely on frequency of testing and speed of reporting and is only marginally improved by high test sensitivity. We therefore conclude that screening should prioritize accessibility, frequency, and sample-to-answer time; analytical limits of detection should be secondary.


Subject(s)
COVID-19 Nucleic Acid Testing , COVID-19/diagnosis , Mass Screening/methods , Viral Load , Asymptomatic Infections , Calibration , Computer Simulation , Epidemics , Humans , Kinetics , Limit of Detection , Models, Theoretical , Polymerase Chain Reaction , Reproducibility of Results , Sensitivity and Specificity , Time Factors
20.
Clin Biochem ; 89: 70-76, 2021 Mar.
Article in English | MEDLINE | ID: covidwho-1032517

ABSTRACT

BACKGROUND: Hydroxychloroquine is an antimalarial drug that has been prescribed for the treatment of patients with COVID-19 infection. To assist in clinician decision-making, several clinical laboratories have developed and validated measurement procedures in-house based on HPLC or HPLC-MS/MS to measure the mass concentration of hydroxychloroquine in different biological fluids. In these cases, laboratories produce their calibration materials but rarely estimate the measurement uncertainty of their assigned values. Thus, we aimed to show how this uncertainty can be calculated, using the preparation of hydroxychloroquine calibrators in blood-hemolysate-based matrix as an example. METHODS: A bottom-up approach was used to estimate the uncertainty related to the values assigned to end-user calibration materials prepared in-house. First, a specification of the measurand and a measurement equation were proposed. Then, different sources of uncertainty related to the preparation of hydroxychloroquine calibration materials were identified and quantified. Afterwards, the combined uncertainty was calculated using the law for the propagation of uncertainty resulting in the final expanded uncertainty. RESULTS: In this study, the most significant source of uncertainty was that associated with the hydroxychloroquine's reference material mass obtained via balance, while the smallest contribution was from the uncertainty associated with the hydroxychloroquine reference material purity. CONCLUSIONS: A simple procedure to estimate the measurement uncertainty of values assigned to calibration materials is presented here, which would be easy to implement in clinical laboratories. Also, it could be put into practice for other pharmacological quantities measured by in-house HPLC or HPLC-MS/MS procedures commonly used in clinical laboratories.


Subject(s)
COVID-19/blood , Chromatography, High Pressure Liquid/methods , Hydroxychloroquine/blood , Antimalarials/administration & dosage , Antimalarials/blood , COVID-19/drug therapy , COVID-19/pathology , COVID-19/virology , Calibration , Chromatography, High Pressure Liquid/standards , Hemolysis , Humans , Hydroxychloroquine/administration & dosage , Quality Control , Reference Standards , SARS-CoV-2/isolation & purification , Uncertainty
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