The evaluation of a novel digital immunochromatographic assay with silver amplification to detect SARS-CoV-2

Introduction Rapid antigen tests are convenient for diagnosing severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2); however, they have lower sensitivities than nucleic acid amplification tests. In this study, we evaluated the diagnostic performance of Quick Chaser Auto SARS-CoV-2, a novel digital immunochromatographic assay that is expected to have higher sensitivity than conventional antigen tests. Methods A prospective observational study was conducted between February 8 and March 24, 2021. We simultaneously obtained two nasopharyngeal samples, one for evaluation with the QuickChaser Auto SARS-CoV-2 antigen test and the other for assessment with reverse transcription PCR (RT-PCR), considered the gold-standard reference test. The limit of detection (LOD) of the new antigen test was compared with those of four other commercially available rapid antigen tests. Results A total of 1401 samples were analyzed. SARS-CoV-2 was detected by reference RT-PCR in 83 (5.9%) samples, of which 36 (43.4%) were collected from symptomatic patients. The sensitivity, specificity, positive predictive value, and negative predictive value were 74.7% (95% confidence interval (CI): 64.0-83.6%), 99.8% (95% CI: 99.5-100%), 96.9% (95% CI: 89.2-99.6%), and 98.4% (95% CI: 97.6-99.0%), respectively. When limited to samples with a cycle threshold (Ct) <30 or those from symptomatic patients, the sensitivity increased to 98.3% and 88.9%, respectively. The QuickChaser Auto SARS-CoV-2 detected 34-120 copies/test, which indicated greater sensitivity than the other rapid antigen tests. Conclusions QuickChaser Auto SARS-CoV-2 showed sufficient sensitivity and specificity in clinical samples of symptomatic patients. The sensitivity was comparable to RT-PCR in samples with Ct<30.

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Role of Covid Antigen in the Diagnosis of Covid Positive in Obstetric Patients

10.53350/pjmhs2115103356 ◽

2021 ◽

Vol 15 (10) ◽

pp. 3356-3358

Author(s):

Ambreen Fatima ◽

Nidda Yaseen ◽

Amna Fareed ◽

Kashif Ali Samin ◽

Shumaela Kanwal ◽

...

Keyword(s):

Nucleic Acid ◽

Early Detection ◽

Negative Predictive Value ◽

Predictive Value ◽

False Negative ◽

Nucleic Acid Amplification ◽

Antigen Test ◽

Rt Pcr ◽

Cross Sectional ◽

Specificity And Sensitivity

Background and Aim: The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) rapid emergence postured significant challenges on the health system in recent years. The early detection of cases is thought to be critical in preventing this pandemic by coronavirus disease (COVID-19), especially important in the obstetrical population due to theirs numerous interactions with another parturient when hospitalized for delivery. Therefore, the present study aimed to assess the COVID antigen test performance in COVID-positive obstetrics patients. Materials and Methods: This cross-sectional study was conducted on 1296 Covid-19 asymptomatic women admitted to the Obstetrics and Gynaecology Department of Muhammad Teaching Hospital & Medical College, Peshawar and Fauji Foundation Hospital, Rawalpindi for the duration of six months from February 2021 to July 2021. Antigen-based test rapid diagnostic test (RDT) was used for screening out COVID-19 positive obstetrics patients or women through nasopharyngeal swabs. Women with negative rapid antigen test results were confirmed with RT-polymers chain reaction test of nucleic acid amplification tests (NAAT). Ethical approval and informed consent were taken from the hospital ethical committee and each individual respectively. All the known positive COVID-19 patients during admission were excluded. SPSS version 24 was used for data analysis. Results: The overall prevalence of rapid antigen-positive tested patients was 13.2% (171/1296). The prevalence of positive tested women through rapid antigen test, Nucleic Acid Amplification Test (NAAT), and RT-PCR were 27 (2.1%), 51 (3.9%), and 93 (7.2%) respectively. Of the total 1296 rapid antigen tests, 27 were positive, and the false-negative confirmed positive by NAAT was 144.Thus the sensitivity of the rapid antigen test was 15.8% and the negative predictive value was 93.7%. Of the total 298 Nucleic Acid Amplification Tested had sensitivity and negative predictive value of 89.6% and 99.06% respectively. RT-PCR was carried out on 972 patients, positive diagnosed cases were 36 while 15 were initially negative and were positive with the test was repeated. The sensitivity and negative predictive value was 71.45% and 95.8% respectively. Conclusion: Our study found that Ag-RDT plays a significant role in SARS-CoV-2 early detection in infected individuals, with high specificity and sensitivity to disease infectious stage, whether symptomatic or asymptomatic, and can be used as a decision supported tool. Early detection of COVID-19 status in women admitted for delivery could benefit neonatal protection care. Keywords: Covid-19; Rapid antigen test; RT-PCR test

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Comparison of a New Gold Immunochromatographic Assay for the Rapid Diagnosis of the Novel Influenza A (H7N9) Virus with Cell Culture and a Real-Time Reverse-Transcription PCR Assay

BioMed Research International ◽

10.1155/2014/425051 ◽

2014 ◽

Vol 2014 ◽

pp. 1-6 ◽

Cited By ~ 4

Author(s):

Changzhong Jin ◽

Nanping Wu ◽

Xiaorong Peng ◽

Hangping Yao ◽

Xiangyun Lu ◽

...

Keyword(s):

Reverse Transcription ◽

Influenza A ◽

High Specificity ◽

High Viral Load ◽

Immunochromatographic Assay ◽

Clinical Samples ◽

H7n9 Virus ◽

Rt Pcr ◽

Reverse Transcription Pcr ◽

Viral Culture

We assessed a colloidal gold immunochromatographic assay (GICA) for rapid detection of influenza A (H7N9) and compared it with reverse-transcription-polymerase chain reaction (RT-PCR) and viral culture. Samples from 35 H7N9 infected patients were collected, including 45 throat swab samples, 56 sputum samples, and 39 feces samples. All samples were tested by GICA, viral culture, and RT-PCR. GICA specifically reacted with recombinant HA proteins, virus lysates, and clinical samples from H7 subtype viruses. Compared with RT-PCR, GICA demonstrated low sensitivity (33.33%) but high specificity (97.56%). The positive rate of GICA tests for samples collected in the period from 8 to 21 days after contact with poultry was much higher than those for samples collected before or after this period. Compared with viral culture, GICA showed sensitivity of 91.67% and specificity of 82.03%. Sputum specimens were more likely to test positive for H7N9 virus than samples from throat swabs and feces. The GICA-based H7 test is a reliable, rapid, and convenient method for the screening and diagnosis of influenza A (H7N9) disease, especially for the sputum specimens with high viral load. It may be helpful in managing H7N9 epidemics and preliminary diagnosis in early stages in resource-limited settings.

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High Sensitivity and NPV for BinaxNOW Rapid Antigen Test in Children at a Mass Testing Site During Prevalent Delta Variant

10.1101/2022.01.05.22268788 ◽

2022 ◽

Author(s):

Kristie J Sun ◽

Mary Jane E Vaeth ◽

Matthew L Robinson ◽

Maryam Elhabashy ◽

Ishaan Gupta ◽

...

Keyword(s):

Predictive Value ◽

High Sensitivity ◽

High Volume ◽

Educational Opportunities ◽

Antigen Test ◽

Sample Collection ◽

Rt Pcr ◽

Polymerase Chain ◽

Testing Site ◽

Antigen Tests

SARS-CoV-2 continues to develop new, increasingly infectious variants, such as delta and omicron. Here, we evaluate the efficacy of the Abbott BinaxNOW Rapid Antigen Test against the gold standard of Reverse Transcription Polymerase Chain Reaction (RT-PCR) in 1054 pediatric participants presenting to a state-owned high-volume Coronavirus Disease 2019 (COVID-19) testing site. During the testing period, the delta variant was predominant. Prior to sample collection, symptomatic and exposure status was collected for all participants based on Centers for Disease Control (CDC) criteria. RT-PCR results demonstrated an overall prevalence rate of 5.2%. For all participants, the sensitivity of the rapid antigen tests was 92.7% (95% CI 82.4% - 98.0%) and specificity was 98.0% (95% CI 97.0%-98.8%). For symptomatic participants, the sensitivity was 92.3% (95% CI 74.9% - 99.1%), specificity was 96.6% (95% CI 93.6%- 98.4%), positive predictive value (PPV) was 72.7% (95% CI 54.5% - 86.7%) and negative predictive value (NPV) was 99.2% (95% CI 98.2% - 100%). Among asymptomatic participants, the sensitivity was 92.6% (95% CI 75.7% - 99.1%), specificity was 98.6% (95% CI 97.5% - 99.3%) the PPV was 71.4% (95% CI 53.7% - 85.4%) and the NPV was 99.7% (95% CI 99.0% - 100%). Our reported sensitivity and NPV are higher than other pediatric studies, but specificity and PPV are lower. Importance Children are especially impacted by the disease and its ability to disrupt educational opportunities. Although vaccinations have been approved for children 5 years and older, many children remain unvaccinated. Widespread testing may improve the ability for children to remain in in-person activities, minimizing absences from school and extracurriculars. Highly accurate rapid antigen tests may be vital to containing future COVID-19 waves while mitigating detrimental effects.

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Accuracy of Roche SARS-CoV-2 Rapid Antigen Test in Nasopharyngeal Swab: Clinical Impression Matters

Journal of Biomedical Research & Environmental Sciences ◽

10.37871/jbres1334 ◽

2021 ◽

Vol 2 (10) ◽

pp. 929-938

Author(s):

Khin Phyu Pyar ◽

Khine Khine Su ◽

Kyaw Wunna ◽

Myo Thant ◽

Kaung Myat ◽

...

Keyword(s):

Predictive Value ◽

False Negative ◽

Hospital Setting ◽

Clinical Samples ◽

Nasopharyngeal Swab ◽

Clinical Impression ◽

Antigen Test ◽

Rt Pcr ◽

Ct Value

Background: In COVID-19 pandemic, the diagnosis and treatment must be as early as possible to save the life of each patient. Moreover, screening of asymptomatic carriers, close contacts or healthy subjects must not be delay to prevent transmission to publics. For confirmation of diagnosis of SARS-CoV-2 infection, nasopharyngeal swab must be tested either by real-time Reverse Transcription Polymerase Chain Reaction (RT-PCR) tests or Rapid Antigen Test (RAT). RAT is faster, easier and cheaper; thus, it is suitable for health service in developing country. Objectives: The aim of this study was to assess the diagnostic accuracy of Roche SARS-CoV-2 Rapid Antigen Test (RAT) in diagnosing SARS-CoV-2 infection. Methods: Hospital based exploratory study was done in out-patient department and fever clinic, and molecular laboratory of No. (1) Defence Services General Hospital. Nasopharyngeal swabs were taken, and the Roche SARS- CoV-2 RAT was conducted in parallel with RT-PCR test (reference standard). Results: Among the 932 patients/subjects recruited, RT-PCR was positive in 468 individuals, corresponding to a prevalence of 50.2%. The RAT was positive in 363 patients (60.4%), false positive in 120 patients; it was negative in 569 individuals (39.6%), false negative in 225 patients. The overall sensitivity of the RAT was 51.9% (95% Confidence Interval [CI] 47.29-56.53) and, the specificity was 74.1% (95% CI 69.9-78.07); positive predictive value was 66.9% and negative predictive value was 60.5%. The sensitivity varied with Ct value; 78% in clinical samples with Ct values < 20, 57.5% in those with Ct values between 21 and 25, 41.8% in samples with Ct values between 26 and 30, and, 36.4% in samples with Ct value > 30. Conclusion: The accuracy of the SARS-CoV-2 Roche RAT in diagnosing SARS-CoV-2 infections was inferior to RT-PCR and manufacturer’s data. The sensitivity was with low Cycle threshold values < 20 which were inversely related to the viral load. RAT test should be used in association with clinical impression of physicians. In hospital setting especially in emergency department, the role of RAT should be reconsidered in those patients presenting with anosmia and some cases of dyspnoea, late symptoms in the course of disease, as the RAT results would be false negative. Other errors may arise if the operator for RAT has to handle more than recommended tests per hour especially in the peak of epidemics.

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366. Abbott BinaxNOW Rapid Antigen Test Performance in Detecting SARS-CoV-2 Infections in a COVID-19 Outbreak Among Horse Racetrack Workers

Open Forum Infectious Diseases ◽

10.1093/ofid/ofab466.567 ◽

2021 ◽

Vol 8 (Supplement_1) ◽

pp. S286-S286

Author(s):

Krishna Surasi ◽

Kristin J Cummings ◽

Carl V Hanson ◽

Mary Kate Morris ◽

Maria Salas ◽

...

Keyword(s):

Test Performance ◽

Predictive Value ◽

Nucleic Acid Amplification ◽

Rt Pcr ◽

Ct Value ◽

Negative Results ◽

Percent Agreement ◽

Nasal Swabs ◽

Antigen Tests ◽

Positive Results

Abstract Background Rapid antigen tests (e.g., Abbott’s BinaxNOW) are cheaper and faster than nucleic acid amplification tests (e.g., real-time reverse transcription polymerase chain reaction [RT-PCR]) for SARS-CoV-2 infection, with variable reported sensitivity. A horse racetrack in California experienced a COVID-19 outbreak among staff and used BinaxNOW to supplement RT-PCR. Utility of BinaxNOW in detecting SARS-CoV-2 infection in a workplace outbreak was assessed. Methods Between November 25–December 22, 2020, anterior nasal swabs were collected from racetrack staff for six rounds of paired BinaxNOW and RT-PCR tests. BinaxNOW tests were interpreted according to manufacturer instructions. RT-PCR was performed at the state public health lab using the ThermoFisher TaqPath COVID-19 Combo Kit. Staff with positive results on either test were isolated and removed from subsequent testing. Viral cultures were attempted on specimens with cycle threshold (Ct) < 30. Results Overall, 769 paired results from 342 staff were analyzed. Most were of Hispanic ethnicity (62.0%) and ages ranged from 18 to 92 years (median 52). BinaxNOW performance compared to RT-PCR (95% CI) was as follows: positive percent agreement (PPA) 43.3% (34.6%–52.4%); negative percent agreement (NPA) 100% (99.4%–100%); positive predictive value (PPV) 100% (93.5%–100%); negative predictive value 89.9% (87.5%–92.0%). Among 127 RT-PCR-positive specimens, those with paired BinaxNOW-positive results (n = 55) had a lower mean Ct value than those with paired BinaxNOW-negative results (n = 72) (17.8 vs. 28.5) (p < 0.001). In dual positive pairs, median time from specimen collected to RT-PCR result reported was 4 days (range 1-6), compared to the 15-minute BinaxNOW reporting time. Of 100 Ct < 30 specimens, 51 resulted in positive virus isolation, 45 (88.2%) of which were BinaxNOW-positive. Conclusion High NPA and PPV support immediate isolation of BinaxNOW-positive individuals, while low PPA supports confirmatory testing following BinaxNOW-negative results. BinaxNOW performed better in paired specimens with lower Ct value and positive viral cultures, which could suggest that among RT-PCR-positive specimens, those that are BinaxNOW-negative may be less likely to contain infectious virus than those that are BinaxNOW-positive. Disclosures David Seftel, M.D., M.D., M.B.A., Enable Biosciences, Inc (Board Member, Employee, Scientific Research Study Investigator, Shareholder)

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Inactivation of SARS-CoV-2 virus in saliva using a guanidium based transport medium suitable for RT-PCR diagnostic assays

PLoS ONE ◽

10.1371/journal.pone.0252687 ◽

2021 ◽

Vol 16 (6) ◽

pp. e0252687

Author(s):

Sukalyani Banik ◽

Kaheerman Saibire ◽

Shraddha Suryavanshi ◽

Glenn Johns ◽

Soumitesh Chakravorty ◽

...

Keyword(s):

Limit Of Detection ◽

Viral Rna ◽

Clinical Samples ◽

Sample Collection ◽

Rt Pcr ◽

Diagnostic Assays ◽

Guanidinium Thiocyanate ◽

Upper Respiratory ◽

Polymerase Chain ◽

The Stability

Background Upper respiratory samples used to test for SARS-CoV-2 virus may be infectious and present a hazard during transport and testing. A buffer with the ability to inactivate SARS-CoV-2 at the time of sample collection could simplify and expand testing for COVID-19 to non-conventional settings. Methods We evaluated a guanidium thiocyanate-based buffer, eNAT™ (Copan) as a possible transport and inactivation medium for downstream Reverse Transcriptase-Polymerase Chain Reaction (RT-PCR) testing to detect SARS-CoV-2. Inactivation of SARS-CoV-2 USA-WA1/2020 in eNAT and in diluted saliva was studied at different incubation times. The stability of viral RNA in eNAT was also evaluated for up to 7 days at room temperature (28°C), refrigerated conditions (4°C) and at 35°C. Results SARS-COV-2 virus spiked directly in eNAT could be inactivated at >5.6 log10 PFU/ml within a minute of incubation. When saliva was diluted 1:1 in eNAT, no cytopathic effect (CPE) on VeroE6 cells was observed, although SARS-CoV-2 RNA could be detected even after 30 min incubation and after two cell culture passages. A 1:2 (saliva:eNAT) dilution abrogated both CPE and detectable viral RNA after as little as 5 min incubation in eNAT. SARS-CoV-2 RNA from virus spiked at 5X the limit of detection remained positive up to 7 days of incubation in all tested conditions. Conclusion eNAT and similar guanidinium thiocyanate-based media may be of value for transport, stabilization, and processing of clinical samples for RT-PCR based SARS-CoV-2 detection.

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Performance evaluation of cobas HBV real-time PCR assay on Roche cobas 4800 System in comparison with COBAS AmpliPrep/COBAS TaqMan HBV Test

Clinical Chemistry and Laboratory Medicine (CCLM) ◽

10.1515/cclm-2017-1133 ◽

2018 ◽

Vol 56 (7) ◽

pp. 1133-1139 ◽

Cited By ~ 7

Author(s):

Hanah Kim ◽

Mina Hur ◽

Eunsin Bae ◽

Kyung-A Lee ◽

Woo-In Lee

Keyword(s):

Real Time ◽

Real Time Pcr ◽

Limit Of Detection ◽

Nucleic Acid Amplification ◽

Coefficient Of Determination ◽

Clinical Samples ◽

Pcr Assay ◽

Cobas Taqman ◽

Limit Of Quantitation ◽

Two Systems

Abstract Background: Hepatitis B virus (HBV) nucleic acid amplification testing (NAAT) is important for the diagnosis and management of HBV infection. We evaluated the analytical performance of the cobas HBV NAAT (Roche Diagnostics GmbH, Mannheim, Germany) on the cobas 4800 System in comparison with COBAS AmpliPrep/COBAS TaqMan HBV Test (CAP/CTM HBV). Methods: Precision was evaluated using three levels of cobas HBV/HCV/HIV-1 Control Kit, and linearity was evaluated across the anticipated measuring range (10.0–1.0×109 IU/mL) at seven levels using clinical samples. Detection capability, including limit of blank (LOB), limit of detection (LOD) and limit of quantitation (LOQ), was verified using the 4th WHO International Standard for HBV DNA for NAT (NIBSC code: 10/266). Correlation between the two systems was compared using 205 clinical samples (102 sera and 103 EDTA plasma). Results: Repeatability and total imprecision (coefficient of variation) ranged from 0.5% to 3.8% and from 0.5% to 3.5%, respectively. Linearity (coefficient of determination, R2) was 0.999. LOB, LOD and LOQ were all acceptable within the observed proportion rate (85%). Correlation was very high between the two systems in both serum and plasma samples (correlation coefficient [r]=0.995). Conclusions: The new cobas HBV real-time PCR assay on the cobas 4800 System showed reliable analytical performances.

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A prospective nationwide observational study of agreement of antigen tests on oral pharyngeal swabs or less invasive testing with RT-qPCR, for detecting SARS-CoV-2 in adults: Protocol description (Preprint)

10.2196/preprints.35706 ◽

2021 ◽

Author(s):

Uffe Vest Schneider ◽

Jenny Dahl Knudsen ◽

Anders Koch ◽

Nikolai Søren Kirkby ◽

Jan Gorm Lisby

Keyword(s):

Confidence Intervals ◽

Predictive Value ◽

Large Scale ◽

Reference Method ◽

Lateral Flow ◽

Clinical Samples ◽

Sampling Location ◽

Analytical Sensitivity ◽

Clinical Sensitivity ◽

Antigen Tests

BACKGROUND The SARS-CoV-2 pandemic has resulted in an unprecedented level of world-wide testing for epidemiologic and diagnostic purposes, and due to the extreme need for tests, the gold standard reverse transcription polymerase chain reaction (RT-qPCR) testing capacity has been unable to meet the overall global testing demand. Consequently, although current literature has shown the sensitivity of rapid antigen tests (RATs) to be inferior to RT-qPCR, RATs have been implemented on a large scale without solid data on performance. OBJECTIVE This study will compare analytical and clinical sensitivities and specificities of 50 lateral flow or laboratory based RATs and three Strand Invasion Based Amplification (SIBA)-rt-PCR tests from 30 manufacturers to RT-qPCR on samples obtained from the deep oropharynx. In addition, the study will compare sensitivities and specificities of the included RATs as well as RT-qPCR on clinical samples obtained from the deep oropharynx, anterior nasal cavity, saliva, deep nasopharynx and expired air to RT-qPCR from deep oropharyngeal samples. METHODS In the prospective part of the study, 200 individuals found SARS-CoV-2 positive and 200 individuals found SARS-CoV-2 negative by routine RT-qPCR testing will be re-tested with each RAT applying RT-qPCR as the reference method. In the retrospective part of the study, 304 deep oropharyngeal cavity swabs divided into four groups based on RT-qPCR Cq levels will be tested by each RAT. RESULTS The results will be reported in several manuscripts with different aims. The first manuscript will report retrospective (analytical sensitivity, overall and stratified into different Cq range groups) and prospective (clinical sensitivity) data for RATs with RT-qPCR results as the reference method. The second manuscript will report results for RAT based on anatomical sampling location. The third manuscript will compare different anatomical sampling locations by RT-qPCR testing. The fourth manuscript will focus on RATs that rely on central laboratory testing. Test from four different manufactures will be compared for analytical performance data on retrospective deep oropharyngeal swab samples. The fifth manuscript will report the results of four RATs applied both as professional use and as self-test. The last manuscript will report the results from two breath tests participating in the study. Comparison of sensitivity and specificity between RATs will be done using McNemar for paired samples and chi-squared test for unpaired samples. Comparison of PPV and NPV between RATs will be done by bootstrap test. 95 % confidence intervals for sensitivity, specificity, positive predictive value and negative predictive value are calculated as bootstrap confidence intervals CONCLUSIONS The study will compare the sensitivities of a large number of RATs for SARS-CoV-2 compared to RT-qPCR and will address whether lateral flow based RATs test differ significantly from laboratory based RATS. The anatomical test location for both RAT and RT-qPCR will be compared. CLINICALTRIAL ClinicalTrials.gov NCT04913116

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Correlation of COVID-19 antigen test and CBNAAT results at a single tertiary care hospital in North India: an experience

International Journal of Community Medicine and Public Health ◽

10.18203/2394-6040.ijcmph20211768 ◽

2021 ◽

Vol 8 (5) ◽

pp. 2427

Author(s):

Surbhi Gupta ◽

Anju Shukla ◽

Poonam Singh ◽

Areena H. Siddiqui

Keyword(s):

Tertiary Care Hospital ◽

Point Of Care ◽

Tertiary Care ◽

Uttar Pradesh ◽

Nucleic Acid Amplification ◽

North India ◽

Care Hospital ◽

Antigen Test ◽

Discordant Group ◽

Antigen Tests

Background: Nucleic acid amplification test (NAAT) is considered gold standard in the molecular diagnosis of CoV-2 infection but since it is costly, labor intensive and needs technical expertise, rapid chromatographic immunoassay for the qualitative detection of specific antigens to SARS CoV-2 have been devised. Objectives of this study was to compare the results of Antigen test and NAAT for CoV-2 infection carried out during the months of July and August 2020 by single tertiary care hospital in Lucknow, Uttar Pradesh and to determine the utility of rapid antigen test in the SARS CoV-2 diagnosis.Methods: All the patients who came to our hospital seeking admission during July 2020 and August 2020 were included in the study. A total of 1000 patients were included in this study.Results: Out of a total 1000 cases which were included in the study, 769 cases (76.9%) were found to be SARS CoV-2 negative by both antigen and CBNAAT, 100 cases (10.0%) were SARS CoV-2 positive by both antigen and CBNAAT tests. But in 131 cases (13.1%), antigen was not able to pick up the disease. It was also found that the Cycle Threshold (Ct) value for the discordant group was higher (Mean E= 28, Mean N2=33) when compared to the group where antigen was positive.Conclusions: The present study establishes the role of rapid antigen tests in contributing to the quick, point of care diagnosis of SARS CoV-2. These assays are safe, simple, and fast and can be used in local clinics and hospitals. These tests are very important for real-time patient management and infection control decision.

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Microfluidic Nano-Scale qPCR Enables Ultra-Sensitive and Quantitative Detection of SARS-CoV-2

Processes ◽

10.3390/pr8111425 ◽

2020 ◽

Vol 8 (11) ◽

pp. 1425

Author(s):

Xin Xie ◽

Tamara Gjorgjieva ◽

Zaynoun Attieh ◽

Mame Massar Dieng ◽

Marc Arnoux ◽

...

Keyword(s):

Viral Infections ◽

Limit Of Detection ◽

False Negative ◽

False Negative Rate ◽

Clinical Samples ◽

Quantitative Detection ◽

Rt Pcr ◽

Viral Loads ◽

Nano Scale ◽

Negative Rate

A major challenge in controlling the COVID-19 pandemic is the high false-negative rate of the commonly used RT-PCR methods for SARS-CoV-2 detection in clinical samples. Accurate detection is particularly challenging in samples with low viral loads that are below the limit of detection (LoD) of standard one- or two-step RT-PCR methods. In this study, we implemented a three-step approach for SARS-CoV-2 detection and quantification that employs reverse transcription, targeted cDNA preamplification, and nano-scale qPCR based on a commercially available microfluidic chip. Using SARS-CoV-2 synthetic RNA and plasmid controls, we demonstrate that the addition of a preamplification step enhances the LoD of this microfluidic RT-qPCR by 1000-fold, enabling detection below 1 copy/µL. We applied this method to analyze 182 clinical NP swab samples previously diagnosed using a standard RT-qPCR protocol (91 positive, 91 negative) and demonstrate reproducible and quantitative detection of SARS-CoV-2 over five orders of magnitude (<1 to 106 viral copies/µL). Crucially, we detect SARS-CoV-2 with relatively low viral load estimates (<1 to 40 viral copies/µL) in 17 samples with negative clinical diagnosis, indicating a potential false-negative rate of 18.7% by clinical diagnostic procedures. In summary, this three-step nano-scale RT-qPCR method can robustly detect SARS-CoV-2 in samples with relatively low viral loads (<1 viral copy/µL) and has the potential to reduce the false-negative rate of standard RT-PCR-based diagnostic tests for SARS-CoV-2 and other viral infections.

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