Performance evaluation of an automated SARS-CoV-2 Ag test for the diagnosis of COVID-19 infection on nasopharyngeal swabs

2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Cédric Hartard ◽  
Sibel Berger ◽  
Thomas Josse ◽  
Evelyne Schvoerer ◽  
Hélène Jeulin
Keyword(s):  
Performance Evaluation ◽  
Negative Predictive Value ◽  
Symptom Onset ◽  
Predictive Value ◽  
Rt Pcr ◽  
Infected People ◽  
Antigen Tests

Abstract Objectives The detection of SARS-CoV-2 in infected people is a key tool to help in controlling COVID-19 pandemic. Like rapid antigenic tests, automated antigen tests, that present the advantage of a higher throughput flow, may be of interest. The LIAISON® SARS-CoV-2 Ag test was evaluated for the quantification of SARS-CoV-2 nucleocapsid antigen in nasopharyngeal swabs by comparison to RT-PCR. Methods The study involved 378 nasopharyngeal samples (UTM® and FLOQSwab™, Copan Diagnostics), including 46 swabs positive for SARS-CoV-2 by RT-PCR. These samples came from asymptomatic (n=99, 26.2%) or symptomatic people (n=279, 73.8%), at different times from symptom onset. The samples were analyzed on LIAISON® XL. Results The overall specificity was 99.4% (CI95% [98.6–100]). The negative predictive value reached 100% in asymptomatic people. Among the 46 positive samples, the overall sensitivity was 84.8% (CI95% [74.4–95.2]), reached 91.9% (CI95% [83.1–100]) in the first fourth days after symptoms onset and was 100% for Cq values ≤25. Antigen was not detected in samples with Cq values >25. Similar results were observed on nasopharyngeal swabs coming from patients infected with the 20I/501Y.V1 variant or the 20H/501Y.V2 variant. Conclusions According to technical performances, the LIAISON® SARS-CoV-2 Ag test may be a useful tool for COVID-19 diagnosis, especially during the first four days of symptoms.

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

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

scholarly journals Sequential battery of COVID-19 testing to maximize negative predictive value before surgeries

2020 ◽  
Vol 47 ◽  
Author(s):  
NEERAJ SINHA ◽  
GALIT BALAYLA
Keyword(s):  
Immune Response ◽  
Negative Predictive Value ◽  
Predictive Value ◽  
Chest Ct ◽  
Viral Dynamics ◽  
Rt Pcr ◽  
Testing Methods ◽  
Course Of Illness ◽  
Epidemiologic Survey ◽  
Novel Virus

ABSTRACT SARS-CoV-2 is a novel virus which has proven to be highly contagious. Specific viral dynamics and immune response to the virus are yet to be fully defined and determining the sensitivity and specificity of the available testing methods is still a work in progress. This study examines the published information on the testing methods, and finds that yield of COVID-19 tests changes with specimen types and with time through course of illness. We propose a sequential battery of testing consisting of an epidemiologic survey, RT-PCR tests, serologic tests and chest CT on surgical candidates which may increase the negative predictive value, and facilitate surgical procedures.

scholarly journals High negative predictive value of RT-PCR in patients with high likelihood of SARS-CoV-2 infection

2021 ◽  
Author(s):  
S Galmiche ◽  
S Fernandes-Pellerin ◽  
MN Ungeheuer ◽  
O Schwartz ◽  
M Attia ◽  
...  
Keyword(s):  
Negative Predictive Value ◽  
Predictive Value ◽  
High Likelihood ◽  
Rt Pcr ◽  
High Negative Predictive Value

scholarly journals The Performance of Two Rapid Antigen Tests During Population-Level Screening for SARS-CoV-2 Infection

2021 ◽  
Vol 8 ◽  
Author(s):  
Mohammad Alghounaim ◽  
Hamad Bastaki ◽  
Farah Bin Essa ◽  
Hoda Motlagh ◽  
Salman Al-Sabah
Keyword(s):  
Positive Predictive Value ◽  
Prospective Study ◽  
Predictive Value ◽  
Point Of Care ◽  
Population Level ◽  
Lower Sensitivity ◽  
Rt Pcr ◽  
Antigen Tests ◽  
A Prospective Study ◽  
Antigen Testing

Background: SARS-CoV-2 antigen assays offer a rapid mean to diagnose and isolate infected individuals. However, their utility in population-level screening is unknown.Objectives: The performance of two antigen tests in detecting SARS-CoV-2 was assessed among individuals randomly selected in the community.Study Design: A prospective study that performed head-to-head comparison of two SARS-CoV-2 antigen assays. Individuals were recruited during community SARS-CoV-2 screening over 10 working days. Demographic and clinical data were collected. Standard Q COVID-19 Ag test, a point-of-care chromatographic assay, was conducted immediately, and then the sample was transported to the virology laboratory to perform PCR and the LIAISON SARS-CoV-2 Ag chemiluminesence immunoassay.Results: respiratory samples from 991 individuals were collected, and 62 were positive by PCR. Inconclusive PCR results were observed in 19 samples and were excluded. The median age of participants was 40.2 years (IQR 32.3–47.8), and 932 (94%) were males. Most (77.4%) of infections were asymptomatic. The sensitivity and the specificity of the LIAISON assay were 43.3% (95%CI 30.6–56.8) and 99.9% (95%CI 99.3–100). The Standard Q assay had lower sensitivity (30.6%, 95%CI 19.6–43.7) but similar specificity (98.8%, 95%CI, 97.8–99.4). Similarly, the LIAISON assay had higher positive predictive value (96.3%, 95%CI 81–99.9% vs. 63.3%, 95%CI, 43.9–80.1%). Both assays performed better in symptomatic patients and among samples with a low-cycle threshold (Ct < 25).Conclusion: In our setting of random community surveillance, rapid antigen testing of nasopharyngeal swabs by either LIAISON SARS-CoV-2 Ag (DiaSorin) or Standard Q COVID-19 Ag (SD Biosensor) was less sensitive to detecting SARS-CoV-2 than the TaqPath COVID-19 RT-PCR.

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

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.

scholarly journals Real-World Clinical Performance of the Abbott Panbio with Nasopharyngeal, Throat and Saliva Swabs Among Symptomatic Individuals with COVID-19

2021 ◽  
Author(s):  
William Stokes ◽  
Byron Berenger ◽  
Danielle Portnoy ◽  
Brittney Scott ◽  
Jonas Szelewicki ◽  
...  
Keyword(s):  
Symptom Onset ◽  
Clinical Performance ◽  
Point Of Care ◽  
Community Setting ◽  
Poor Performance ◽  
Community Assessment ◽  
Rt Pcr ◽  
United States Food ◽  
States Food ◽  
Antigen Tests

BACKGROUND Point of Care Testing (POCT) SARS-CoV-2 antigen tests, such as the Abbott Panbio, have great potential to help combat the COVID-19 pandemic. The Panbio is United States Food and Drug Administration (FDA) approved for the detection of SARS-CoV-2 in symptomatic individuals within the first 7 days of COVID-19 symptom onset(s). METHODS Symptomatic adults recently diagnosed with COVID-19 in the community were recruited into the study. Paired nasopharyngeal (NP), throat, and saliva swabs were collected, with one paired swab tested immediately with the Panbio, and the other transported in universal transport media and tested using reverse-transcriptase polymerase chain reaction (RT-PCR). Positive percent agreement (PPA) was calculated. Subsequently, individuals within 7 days of symptom onset who presented to community assessment centres for SARS-CoV-2 testing had Panbio testing completed and paired with RT-PCR results from parallel NP or throat swabs. RESULTS 145 individuals were included in the study. Collection of throat and saliva was stopped early due to poor performance (throat PPA 57.7%, n=61, and saliva PPA 2.6%, n=41). NP swab PPA was 87.7% [n=145, 95% confidence interval 81.0% - 92.7%]. There were 1,641 symptomatic individuals tested by Panbio in community assessment centres, with 268/1641 (16.3%) positive for SARS-CoV-2. There were 37 false negatives, corresponding to a PPA of 86.2% [81.5% - 90.1%]. CONCLUSIONS The Panbio test reliably detects most cases of SARS-CoV-2 from adults in the POCT community setting presenting within 7 days of symptom onset using nasopharyngeal swabs. Throat and saliva swabs are not reliable specimens for the Panbio.

scholarly journals LUNG ULTRASOUND IN RULING OUT COVID-19 AMONG HEALTHCARE WORKERS IN TWO ITALIAN EMERGENCY DEPARTMENTS: A MULTICENTER STUDY.

2021 ◽  
Author(s):  
Roberto Copetti ◽  
Giulia Amore ◽  
Caterina Giudice ◽  
Daniele Orso ◽  
Silvia Cola ◽  
...  
Keyword(s):  
Negative Predictive Value ◽  
Predictive Value ◽  
Emergency Departments ◽  
Healthcare Workers ◽  
Lung Ultrasound ◽  
False Negative ◽  
Nasopharyngeal Swab ◽  
Rt Pcr ◽  
Negative Case ◽  
Adjudication Committee

Purpose: The high percentage of asymptomatic patients and the non-high sensitivity of real-time reverse transcription-polymerase chain reaction (RT-PCR) test on nasopharyngeal swab cause some healthcare workers to be infected but asymptomatic and a source of spread of the epidemic. This study aimed to verify if the lung ultrasound (LUS) had enough high negative predictive value to rule out coronavirus disease 2019 (COVID-19) among a population of healthcare workers operating in the Emergency Department. Methods: A multicenter prospective observational study was conducted, enrolling healthcare workers among the staff of two Emergency Departments in Northeast Italy. The definitive diagnosis of COVID-19 was established by an adjudication committee, based on the clinical data and RT-PCR on nasopharyngeal swab result. Results: From March 30, 2020, to April 22, 2020, we enrolled 155 cases. The adjudication committee determined two true positives for COVID-19. Twenty-one healthcare workers presented suggestive symptoms (2 true positives and 19 false positives). The nasopharyngeal swab was positive in one case (1 false-negative case). LUS was suggestive for COVID-19 pneumonia in 4 cases (2 false-positive cases). The diagnostic accuracy of LUS was 98.7% (95% CI 95.4%-99.8%). The sensitivity and the specificity of LUS were 100% (95% CI 15.8% -100%) and 98.7% (95% CI 95.4% - 99.8%), respectively. The negative predictive value was 100% (95% CI 100% -100%). Conclusion: LUS has a good enough negative predictive value for ruling out COVID-19 in a population of healthcare workers exposed to COVID-19.

scholarly journals Fast Detection of SARS-CoV-2 RNA Directly from Respiratory Samples Using a Loop-Mediated Isothermal Amplification (LAMP) Test

Viruses ◽  
2021 ◽  
Vol 13 (5) ◽  
pp. 801
Author(s):  
Olympia E. Anastasiou ◽  
Caroline Holtkamp ◽  
Miriam Schäfer ◽  
Frieda Schön ◽  
Anna Maria Eis-Hübinger ◽  
...  
Keyword(s):  
Predictive Value ◽  
Lamp Assay ◽  
Detection Methods ◽  
Analytical Sensitivity ◽  
Rt Pcr ◽  
Viral Transport Medium ◽  
Rapid Tests ◽  
Sous Vide ◽  
Antigen Tests ◽  
Isothermal Assay

The availability of simple SARS-CoV-2 detection methods is crucial to contain the COVID-19 pandemic. This study examined whether a commercial LAMP assay can reliably detect SARS-CoV-2 genomes directly in respiratory samples without having to extract nucleic acids (NA) beforehand. Nasopharyngeal swabs (NPS, n = 220) were tested by real-time reverse transcription (RT)-PCR and with the LAMP assay. For RT-PCR, NA were investigated. For LAMP, NA from 26 NPS in viral transport medium (VTM) were tested. The other 194 NPS were analyzed directly without prior NA extraction (140 samples in VTM; 54 dry swab samples stirred in phosphate buffered saline). Ten NPS were tested directly by LAMP using a sous-vide cooking unit. The isothermal assay demonstrated excellent specificity (100%) but moderate sensitivity (68.8%), with a positive predictive value of 1 and a negative predictive value of 0.65 for direct testing of NPS in VTM. The use of dry swabs, even without NA extraction, improved the analytical sensitivity; up to 6% of samples showed signs of inhibition. LAMP could be performed successfully with a sous-vide cooking unit. This technique is very fast, requires little laboratory resources, and can replace rapid antigen tests or verify reactive rapid tests on-site.

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

2021 ◽  
Author(s):  
Yoko Kurihara ◽  
Yoshihiko Kiyasu ◽  
Yusaku Akashi ◽  
Yuto Takeuchi ◽  
Kenji Narahara ◽  
...  
Keyword(s):  
Predictive Value ◽  
Limit Of Detection ◽  
The Other ◽  
Nucleic Acid Amplification ◽  
Immunochromatographic Assay ◽  
Clinical Samples ◽  
Antigen Test ◽  
Rt Pcr ◽  
Reverse Transcription Pcr ◽  
Antigen Tests

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.

scholarly journals Early clinical markers of aggressive multiple sclerosis

Brain ◽  
2020 ◽  
Vol 143 (5) ◽  
pp. 1400-1413 ◽  
Author(s):  
Charles B Malpas ◽  
Ali Manouchehrinia ◽  
Sifat Sharmin ◽  
Izanne Roos ◽  
Dana Horakova ◽  
...  
Keyword(s):  
Multiple Sclerosis ◽  
Positive Predictive Value ◽  
Negative Predictive Value ◽  
Symptom Onset ◽  
Predictive Value ◽  
Bayesian Model ◽  
Bayesian Model Averaging ◽  
Model Averaging ◽  
First Year ◽  
Clinical Markers

Abstract Patients with the ‘aggressive’ form of multiple sclerosis accrue disability at an accelerated rate, typically reaching Expanded Disability Status Score (EDSS) ≥ 6 within 10 years of symptom onset. Several clinicodemographic factors have been associated with aggressive multiple sclerosis, but less research has focused on clinical markers that are present in the first year of disease. The development of early predictive models of aggressive multiple sclerosis is essential to optimize treatment in this multiple sclerosis subtype. We evaluated whether patients who will develop aggressive multiple sclerosis can be identified based on early clinical markers. We then replicated this analysis in an independent cohort. Patient data were obtained from the MSBase observational study. Inclusion criteria were (i) first recorded disability score (EDSS) within 12 months of symptom onset; (ii) at least two recorded EDSS scores; and (iii) at least 10 years of observation time, based on time of last recorded EDSS score. Patients were classified as having ‘aggressive multiple sclerosis’ if all of the following criteria were met: (i) EDSS ≥ 6 reached within 10 years of symptom onset; (ii) EDSS ≥ 6 confirmed and sustained over ≥6 months; and (iii) EDSS ≥ 6 sustained until the end of follow-up. Clinical predictors included patient variables (sex, age at onset, baseline EDSS, disease duration at first visit) and recorded relapses in the first 12 months since disease onset (count, pyramidal signs, bowel-bladder symptoms, cerebellar signs, incomplete relapse recovery, steroid administration, hospitalization). Predictors were evaluated using Bayesian model averaging. Independent validation was performed using data from the Swedish Multiple Sclerosis Registry. Of the 2403 patients identified, 145 were classified as having aggressive multiple sclerosis (6%). Bayesian model averaging identified three statistical predictors: age &gt; 35 at symptom onset, EDSS ≥ 3 in the first year, and the presence of pyramidal signs in the first year. This model significantly predicted aggressive multiple sclerosis [area under the curve (AUC) = 0.80, 95% confidence intervals (CIs): 0.75, 0.84, positive predictive value = 0.15, negative predictive value = 0.98]. The presence of all three signs was strongly predictive, with 32% of such patients meeting aggressive disease criteria. The absence of all three signs was associated with a 1.4% risk. Of the 556 eligible patients in the Swedish Multiple Sclerosis Registry cohort, 34 (6%) met criteria for aggressive multiple sclerosis. The combination of all three signs was also predictive in this cohort (AUC = 0.75, 95% CIs: 0.66, 0.84, positive predictive value = 0.15, negative predictive value = 0.97). Taken together, these findings suggest that older age at symptom onset, greater disability during the first year, and pyramidal signs in the first year are early indicators of aggressive multiple sclerosis.

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