scholarly journals Diagnostic Performance of SARS-CoV-2 Rapid Antigen Test in a Large, German Cohort

Children ◽  
2021 ◽  
Vol 8 (8) ◽  
pp. 682
Author(s):  
Olivier Mboma ◽  
Elmar Rieke ◽  
Parviz Ahmad-Nejad ◽  
Stefan Wirth ◽  
Malik Aydin
Keyword(s):  
Clinical Practice ◽  
Diagnostic Performance ◽  
False Negative ◽  
University Hospital ◽  
True Positive ◽  
Antigen Test ◽  
Rt Pcr ◽  
Everyday Clinical Practice ◽  
Ct Value ◽  
The Right

We assessed the performance of a rapid antigen test (RAT) in everyday clinical practice. Between 1 November 2020 until 1 April 2021 all in-patients at the Helios University Hospital Wuppertal, Germany, as well as the accompanying relatives at the Children’s Hospital received a SARS-CoV-2 RAT and a SARS-CoV-2 RT-PCR prior to admission. Out of 3686 patients, 22 (0.6%) subjects were tested positive by RT-PCR and RAT, and 3591 (97.4%) were negative by both methods, showing discordant results: RT-PCR+/RAT− in 58 (1.6%) and RT-PCR−/RAT+ in 15 patients (0.4%). Overall sensitivity and specificity of RAT was 27.5% (95%CI 18.1–38.6%) and 99.6% (95%CI 99.3–99.8%), respectively. The sensitivity was slightly higher in adults (30.4%, 95%CI 18.8–90.9%) than in pediatric subjects (20.8%, 95%CI 7.1–42.2%). False negative RAT had a statistically higher Ct-value (p < 0.001) compared to true positive values, and overall sensitivity increased to 80% [59.3–93.2%] with Ct value < 30. While the sensitivity of the RAT was poor compared with the RT-PCR, the specificity was excellent. However, the sensitivity increased with lower Ct value, and with the right anamnesis the RAT can be a quick and easy approach to distinguish people who are infectious with SARS-CoV-2 from noninfectious people, enabling appropriate triage in clinical practice while waiting for the RT-PCR result.

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

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.

scholarly journals Viral Dynamics and Real-Time RT-PCR Ct Values Correlation with Disease Severity in COVID-19

Diagnostics ◽  
2021 ◽  
Vol 11 (6) ◽  
pp. 1091
Author(s):  
Ali A. Rabaan ◽  
Raghavendra Tirupathi ◽  
Anupam A Sule ◽  
Jehad Aldali ◽  
Abbas Al Mutair ◽  
...  
Keyword(s):  
Viral Load ◽  
Real Time ◽  
Disease Severity ◽  
False Negative ◽  
Influential Factors ◽  
Confirmatory Test ◽  
Acid Extraction ◽  
Rt Pcr ◽  
Viral Kinetics ◽  
Ct Value

Real-time RT-PCR is considered the gold standard confirmatory test for coronavirus disease 2019 (COVID-19). However, many scientists disagree, and it is essential to understand that several factors and variables can cause a false-negative test. In this context, cycle threshold (Ct) values are being utilized to diagnose or predict SARS-CoV-2 infection. This practice has a significant clinical utility as Ct values can be correlated with the viral load. In addition, Ct values have a strong correlation with multiple haematological and biochemical markers. However, it is essential to consider that Ct values might be affected by pre-analytic, analytic, and post-analytical variables such as collection technique, specimen type, sampling time, viral kinetics, transport and storage conditions, nucleic acid extraction, viral RNA load, primer designing, real-time PCR efficiency, and Ct value determination method. Therefore, understanding the interpretation of Ct values and other influential factors could play a crucial role in interpreting viral load and disease severity. In several clinical studies consisting of small or large sample sizes, several discrepancies exist regarding a significant positive correlation between the Ct value and disease severity in COVID-19. In this context, a revised review of the literature has been conducted to fill the knowledge gaps regarding the correlations between Ct values and severity/fatality rates of patients with COVID-19. Various databases such as PubMed, Science Direct, Medline, Scopus, and Google Scholar were searched up to April 2021 by using keywords including “RT-PCR or viral load”, “SARS-CoV-2 and RT-PCR”, “Ct value and viral load”, “Ct value or COVID-19”. Research articles were extracted and selected independently by the authors and included in the present review based on their relevance to the study. The current narrative review explores the correlation of Ct values with mortality, disease progression, severity, and infectivity. We also discuss the factors that can affect these values, such as collection technique, type of swab, sampling method, etc.

scholarly journals Repetition of microbiological tests in suspect of SARS-CoV-2 infection: utility of a score based on clinical probability

2020 ◽  
Vol 33 (6) ◽  
pp. 410-414
Author(s):  
Javier Pardo Lledias ◽  
Laura Ayarza ◽  
Pablo González-García ◽  
Zaida Salmón González ◽  
Jorge Calvo Montes ◽  
...  
Keyword(s):  
False Negative ◽  
Serum Lactate ◽  
University Hospital ◽  
Serum Lactate Dehydrogenase ◽  
Sampling Errors ◽  
Rt Pcr ◽  
Negative Results ◽  
Clinical Probability ◽  
Clinical Scenarios ◽  
Test Probability

Background. The diagnosis of SARS-CoV-2 infection presents some limitations. RT-PCR in nasopharyngeal swabs is considered the gold standard for the diagnosis, although it can have false negative results. We aimed to analyze the accuracy of repeating nasopharyngeal swabs based on different clinical probabilities. Methods. Retrospective observational study of the first patients admitted to a two COVID Internal Medicine wards at the University Hospital Marqués de Valdecilla, Santander, from March to April 2020. RT-PCR targering E, N, RdRP and ORFab1 genes and antibody tests detecting IgG. Results. A total of 145 hospitalized patients with suspected SARS-Cov2 infection were admitted and in 98 (67.5%) diagnosis was confirmed. The independent predictive variables for SARS-CoV-2 infection were: epidemiological contact, clinical presentation as pneumonia, absence of pneumonia in the last year, onset of symptoms > 7 days, two or more of the following symptoms -dyspnea, cough or fever- and serum lactate dehydrogenase levels >350 U/L (p<0.05). A score based on these variables yielded an AUC-ROC of 0.89 (CI95%, 0.831-0.946; p<0.001). The accuracy of the first nasopharyngeal swabs was 54.9%. Repeating nasopharyngeal swabs two or three times allows to detect an additional 16% of positive cases. The overall accuracy of successive RT-PCR tests in patients with low pre-test probability was <5%. Conclusions. We have defined a pre-test probability score based on epidemiological and clinical data with a high accuracy for diagnosis of SARS-CoV-2. Repeating nasopharyngeal swabs avoids sampling errors, but only in medium of high probability pre-test clinical scenarios.

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 Performance of SARS-CoV-2 rapid antigen test compared with real-time RT-PCR in asymptomatic individuals

2021 ◽  
Author(s):  
Mónica Peña ◽  
Manuel Ampuero ◽  
Carlos Garcés ◽  
Aldo Gaggero ◽  
Patricia García ◽  
...  
Keyword(s):  
Real Time ◽  
False Negative ◽  
Pivotal Role ◽  
Contact Tracing ◽  
Antigen Test ◽  
Rt Pcr ◽  
Asymptomatic Carriers ◽  
Asymptomatic Individuals ◽  
Pcr Diagnostics

AbstractScreening, testing and contact tracing plays a pivotal role in the control of COVID-19 pandemic. To carry out this strategy it is necessary to increase the testing capacity. Here, we compared a SARS CoV-2 rapid antigen test (RAT) and RT-PCR in 842 asymptomatic individuals from Tarapacá, Chile. We report a sensibility of 69.86%, a specificity of 99.61%, PPV of 94.44% and NPP of 97.22% with Ct values (Ct > 27) that were significantly higher among individuals with false-negative RAT. These results support the fact that RAT might have a significant impact in the identification of asymptomatic carriers in areas that lack well-equipped laboratories to perform SARS-CoV-2 real -time RT-PCR diagnostics or the results take more than 24-48 hours, as well as zones with high traffic of individuals, such as border/customs, airports, interregional bus, train stations or in any mass testing campaign requiring rapid results.

scholarly journals Diagnostic performance of a novel digital immunoassay (RapidTesta SARS-CoV-2): a prospective observational study with 1,127 nasopharyngeal samples

2021 ◽  
Author(s):  
Hiromichi Suzuki ◽  
Yusaku Akashi ◽  
Atsuo Ueda ◽  
Yoshihiko Kiyasu ◽  
Yuto Takeuchi ◽  
...  
Keyword(s):  
Diagnostic Performance ◽  
Prospective Observational Study ◽  
Test Results ◽  
Antigen Test ◽  
Rt Pcr ◽  
Asymptomatic Patients ◽  
Pcr Method ◽  
Antigen Tests ◽  
Positive Line ◽  
Test Cassette

Introduction: Digital immunoassays are generally regarded as superior tests for the detection of infectious disease pathogens, but there have been insufficient data concerning SARS-CoV-2 immunoassays. Methods: We prospectively evaluated a novel digital immunoassay (RapidTesta SARS-CoV-2). Two nasopharyngeal samples were simultaneously collected for antigen tests and RT-PCR. Real-time RT-PCR for SARS-CoV-2, using a method developed by the National Institute of Infectious Diseases, Japan, served as the reference RT-PCR method. Results: During the study period, 1,127 nasopharyngeal samples (symptomatic patients: 802, asymptomatic patients: 325) were evaluated. For digital immunoassay antigen tests, the sensitivity was 78.3% (95% CI: 67.3%-87.1%) and the specificity was 97.6% (95% CI: 96.5%-98.5%). When technicians visually analyzed the antigen test results, the sensitivity was 71.6% (95% CI: 59.9%-81.5%) and the specificity was 99.2% (95% CI: 98.5%-99.7%). Among symptomatic patients, the sensitivity was 89.4% (95% CI; 76.9%-96.5%) with digital immunoassay antigen tests, and 85.1% (95% CI; 71.7%-93.8%) with visually analyzed the antigen test, respectively. Conclusions: The findings indicated that RapidTesta SARS-CoV-2 analysis with the DIA device had sufficient analytical performance for the detection of SARS-CoV-2 in nasopharyngeal samples. When positive DIA results are recorded without a visually recognizable red line at the positive line location on the test cassette, additional RT-PCR evaluation should be performed.

scholarly journals Potential Use of Antigen-Based Rapid Test for SARS-CoV-2 in Respiratory Specimens in Low-Resource Settings in Egypt for Symptomatic Patients and High-Risk Contacts

2020 ◽  
Author(s):  
Abeer Mohamed Abdelrazik ◽  
Shahira Morsy Elshafie ◽  
Hossam M Abdelaziz
Keyword(s):  
Test Performance ◽  
Healthcare Professionals ◽  
Rapid Test ◽  
University Hospital ◽  
Antigen Test ◽  
Rt Pcr ◽  
Viral Loads ◽  
Viral Transport Medium ◽  
Public Health Challenges ◽  
Polymerase Chain

Abstract Objective Because of the rapidly emerging SARS-CoV-2 pandemic and its wide public health challenges, rapid diagnosis is essential to decrease the spread. Antigen-based rapid detection tests are available; however, insufficient data about their performance are available. Methods The lateral-flow immunochromatographic BIOCREDIT COVID-19 antigen test was evaluated using nasopharyngeal swabs in a viral transport medium from patients with confirmed infection, contacts, and exposed healthcare professionals at Fayoum University Hospital in Egypt. Test performance was determined in comparison to the SARS-CoV-2 real-time reverse-transcription polymerase chain reaction (RT-PCR) test. Results Three hundred ten specimens from 3 categories—patients with confirmed diagnoses of COVID-19, contacts, and exposed healthcare professionals—were included; 188 specimens were RT-PCR-positive, from which 81 were detected by rapid antigen test. Overall sensitivity was 43.1%. Sensitivity was significantly higher in specimens with high viral loads. Conclusion Poor sensitivity of the BIOCREDIT COVID-19 test does not permit its use for diagnosis, and it can only be used in conjunction with RT-PCR for screening.

scholarly journals Asymptomatic screening of SARS-CoV-2 (COVID-19) virus RNA using reverse transcriptase loop-mediated isothermal amplification (RT-LAMP)

2021 ◽  
Author(s):  
Rebecca Allsopp ◽  
Caroline Cowley ◽  
Ruth Barber ◽  
Carolyn Jones ◽  
Christopher Holmes ◽  
...  
Keyword(s):  
Diagnostic Performance ◽  
Screening Program ◽  
False Negative ◽  
Rna Extraction ◽  
Lamp Assay ◽  
Molecular Diagnostic ◽  
Acid Extraction ◽  
Rt Pcr ◽  
Clinical Patient ◽  
The University

Abstract This study demonstrates the diagnostic performance of SARS-CoV-2 RT-LAMP assays, comparing the performance of genomic versus sub-genomic sequence target with subsequent application in an asymptomatic screening population. An RT-LAMP workflow was developed using synthetic positive control RNA and the diagnostic sensitivity and specificity was then determined using clinical patient samples processed through the diagnostic RT-PCR service within the University Hospitals of Leicester NHS Trust. 92 RT-PCR clinically positive and 88 RT-PCR clinically negative swab samples along with 78 clinically positive and 63 clinically negative saliva samples were equally detected at 100% DSe and 100% DSp for all samples reporting a Ct < 20. DSe for all samples reporting a Ct < 30 reduced slightly to around 95% (100% DSp) for both the single genomic (large open reading frame; orf1a) and dual sub-genomic (nucleocapsid plus envelope) targeting RT-LAMP assays. Lastly, the diagnostic performance of a saliva direct workflow was only about 50% that of the saliva RNA extraction workflow. Subsequently, a swab based RNA -RT-LAMP assay was implemented to ISO 15189:2012 standards supporting an advisory COVID-19 screening program for staff and students at the University of Leicester between October and December 2020. Within a 24-hour period, total nucleic acid extraction was followed by genomic target RT-LAMP plus an internal total RNA control to mitigate the possibility of false negative reporting. SARS-CoV-2 RT-LAMP positive samples were confirmed by an RT-PCR test in an NHS diagnostic laboratory and results were included within national statistics. Nine confirmed positive samples were detected in 1680 symptom free individuals (equivalent to 540 cases per 100,000) thus demonstrating the utility of RT-LAMP molecular diagnostic tool for the detection of SARS-CoV-2 in an asymptomatic population.

scholarly journals Prospective analytical performance evaluation of the QuickNavi™-COVID19 Ag for asymptomatic individuals

2021 ◽  
Author(s):  
Yoshihiko Kiyasu ◽  
Yuto Takeuchi ◽  
Yusaku Akashi ◽  
Daisuke Kato ◽  
Miwa Kuwahara ◽  
...  
Keyword(s):  
Real Time ◽  
Diagnostic Performance ◽  
False Positives ◽  
Clinical Samples ◽  
Lower Sensitivity ◽  
Antigen Test ◽  
Rt Pcr ◽  
Asymptomatic Group ◽  
Asymptomatic Volunteers ◽  
Asymptomatic Individuals

AbstractIntroductionAntigen testing may help screen for and detect severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infections in asymptomatic individuals. However, limited data regarding the diagnostic performance of antigen tests for this group are available.MethodsWe used clinical samples to prospectively evaluate the analytical and clinical performance of the antigen test QuickNavi™-COVID19 Ag. This study was conducted at a PCR center between October 7, 2020 and January 9, 2021. Two nasopharyngeal samples per patient were obtained with flocked swabs; one was used for the antigen test, and the other for real-time reverse transcription PCR (RT-PCR). The diagnostic performance of the antigen test was compared between asymptomatic and symptomatic patients, and the RT-PCR results were used as a reference.ResultsAmong the 1,934 collected samples, SARS-CoV-2 was detected by real-time RT-PCR in 188 (9.7%); 76 (40.4%) of these samples were from asymptomatic individuals. Over half of the total samples (1,073; 55.5%) were obtained from asymptomatic volunteers. The sensitivity of the antigen test was significantly lower for asymptomatic group than for symptomatic patients (67.1% vs 89.3%, p < 0.001). The specificity was 100% for both groups, and no false positives were observed among all 1,934 samples. The median Ct value for the asymptomatic group was significantly higher than that of the symptomatic group (24 vs 20, p < 0.001).ConclusionsThe QuickNavi™-COVID19 Ag showed a lower sensitivity for asymptomatic group than for symptomatic patients. However, its specificity was consistently high, and no false positives were found in this study.

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