scholarly journals Performance characteristics of the Abbott BinaxNOW SARS-CoV-2 antigen test in comparison to real-time RT-PCR and viral culture in community testing sites during November 2020

Author(s):  
Olivia Almendares ◽  
Jessica L. Prince-Guerra ◽  
Leisha D. Nolen ◽  
Jayleen K.L. Gunn ◽  
Ariella P. Dale ◽  
...  

Point-of-care antigen tests are an important tool for SARS-CoV-2 detection. Antigen tests are less sensitive than real-time reverse-transcriptase PCR (rRT-PCR). Data on the performance of the BinaxNOW antigen test compared to rRT-PCR and viral culture by symptom and known exposure status, timing during disease or exposure period and demographic variables are limited. During November 3 rd -17 th , 2020, we collected paired upper respiratory swab specimens to test for SARS-CoV-2 by rRT-PCR and Abbott BinaxNOW (BinaxNOW) antigen test at two community testing sites in Pima County, Arizona. We administered a questionnaire to capture symptoms, known exposure status and previous SARS-CoV-2 test results. Specimens positive by either test were analyzed by viral culture. Previously we showed overall BinaxNOW sensitivity was 52.5%. Here we showed BinaxNOW sensitivity increased to 65.7% among currently symptomatic individuals reporting a known exposure. BinaxNOW sensitivity was lower among participants with a known exposure and previously symptomatic (32.4%) or never symptomatic (47.1%) within 14 days of testing. Sensitivity was 71.1% in participants within a week of symptom onset. In participants with a known exposure, sensitivity was highest 8-10 days post-exposure (75%). The positive predictive value for recovery of virus in cell culture was 56.7% for BinaxNOW-positive and 35.4% for rRT-PCR-positive specimens. Result reporting time was 2.5 hours for BinaxNOW and 26 hours for rRT-PCR. Point-of-care antigen tests have a shorter turn-around time compared to laboratory-based nucleic acid amplification tests, which allows for more rapid identification of infected individuals. Antigen test sensitivity limitations are important to consider when developing a testing program.

Author(s):  
Surbhi Gupta ◽  
Anju Shukla ◽  
Poonam Singh ◽  
Areena H. Siddiqui

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.


Viruses ◽  
2021 ◽  
Vol 14 (1) ◽  
pp. 17
Author(s):  
Adrianna Klajmon ◽  
Aldona Olechowska-Jarząb ◽  
Dominika Salamon ◽  
Agnieszka Sroka-Oleksiak ◽  
Monika Brzychczy-Włoch ◽  
...  

Diagnostics of the coronavirus disease 2019 (COVID-19) using molecular techniques from the collected respiratory swab specimens requires well-equipped laboratory and qualified personnel, also it needs several hours of waiting for results and is expensive. Antigen tests appear to be faster and cheaper but their sensitivity and specificity are debatable. The aim of this study was to compare a selected antigen test with quantitative polymerase chain reaction (qPCR) tests results. Nasopharyngeal swabs were collected from 192 patients with COVID-19 symptoms. All samples were tested using Vitassay qPCR SARS-CoV-2 kit and the Humasis COVID-19 Ag Test (MedSun) antigen immunochromatographic test simultaneously. Ultimately, 189 samples were tested; 3 samples were excluded due to errors in taking swabs. The qPCR and antigen test results were as follows: 47 positive and 142 negative, and 45 positive and 144 negative, respectively. Calculated sensitivity of 91.5% and specificity of 98.6% for the antigen test shows differences which are not statistically significant in comparison to qPCR. Our study showed that effectiveness of the antigen tests in rapid laboratory diagnostics is high enough to be an alternative and support for nucleic acid amplification tests (NAAT) in the virus replication phase in the course of COVID-19.


2021 ◽  
Author(s):  
Laura Ford ◽  
Melissa J. Whaley ◽  
Melisa M. Shah ◽  
Phillip P. Salvatore ◽  
Hannah E. Segaloff ◽  
...  

Background: Performance characteristics of SARS-CoV-2 antigen tests among children are limited despite the need for point-of-care testing in school and childcare settings. We describe children seeking SARS-CoV-2 testing at a community site and compare antigen test performance to real-time reverse transcription-polymerase chain reaction (RT-PCR) and viral culture. Methods: Two anterior nasal specimens were self-collected for BinaxNOW antigen and RT-PCR testing, along with demographics, symptoms, and exposure information from individuals ≥5 years at a community testing site. Viral culture was attempted on residual antigen or RT-PCR positive specimens. Demographic and clinical characteristics, and the performance of SARS-CoV-2 antigen tests, were compared among children (<18 years) and adults. Results: About one in ten included specimens were from children (225/2110); 16.4% (37/225) were RT-PCR positive. Cycle threshold values were similar among RT-PCR positive specimens from children and adults (22.5 vs 21.3, p=0.46) and among specimens from symptomatic and asymptomatic children (22.5 vs 23.2, p=0.39). Sensitivity of antigen test compared to RT-PCR was 73.0% (27/37) among specimens from children and 80.8% (240/297) among specimens from adults; among specimens from children, specificity was 100% (188/188), positive and negative predictive value were 100% (27/27) and 94.9% (188/198) respectively. Virus was isolated from 51.4% (19/37) of RT-PCR positive pediatric specimens; all 19 had positive antigen test results. Conclusions : With lower sensitivity relative to RT-PCR, antigen tests may not diagnose all positive COVID-19 cases; however, antigen testing identified children with live SARS-CoV-2 virus.


2021 ◽  
Author(s):  
Johannes G.M. Koeleman ◽  
Henk Brand ◽  
Stijn J. de Man ◽  
David Ong

Abstract Purpose: The RT-qPCR in respiratory specimens is the gold standard for diagnosing acute COVID-19 infections. However, this test takes considerable time before test results become available, thereby delaying diagnosed COVID-19 patients to be treated and isolated immediately. Rapid antigen tests could overcome this problem and therefore a large number of COVID-19 rapid antigen tests have been developed. Methods: In this study clinical performances of five rapid antigen tests were compared to RT-qPCR in upper respiratory specimens from 80 patients. In addition, the rapid antigen test with the best test characteristics (Romed) was evaluated in a large prospective collection of randomly selected upper respiratory specimens from 900 different COVID-19 suspected patients (300 emergency room patients, 300 nursing home patients and 300 health care workers) in the period from October 24 to November 15, 2020. Results: Overall specificity was almost 100% and sensitivity ranged from 55.0% to 80.0%. The clinical specificity of the Romed test was 99.8% (95% CI 98.9-100). Overall clinical sensitivity in the study population was 73.3% (95% CI 67.9-78.2), whereas sensitivity in the different groups varied from 65.3% to 86.7%. Sensitivity was highest in patients with short-term symptoms. In a population with a COVID-19 prevalence of 1% the negative predictive value in all patients was 99.7%. Conclusion: There is a large variability in diagnostic performance between rapid antigen tests. The Romed rapid antigen test showed a good clinical performance in patients with high viral loads, which makes this antigen test suitable for rapid identification of COVID-19 infected patients.


2020 ◽  
Vol 13 (1) ◽  
Author(s):  
Viktor Szatmári ◽  
Martin Willem van Leeuwen ◽  
Christine Jantine Piek ◽  
Luigi Venco

Abstract Background Dirofilaria immitis is responsible for heartworm disease in dogs in endemic areas worldwide. Screening for this infection is done by blood tests. Antigen testing is the most sensitive method to detect an infection with adult (female) worms. Microscopic examination of a blood smear or Knott’s test can be used to detect circulating microfilariae, the infective larvae. To increase the sensitivity of the antigen test by decreasing the false negative test results, heating of the blood sample has been recommended in recent guidelines. Heating is believed to remove blocking immune-complexes. Circulating microfilariae are not specific findings for heartworm infection, as other nematodes (among others, Acanthocheilonema dracunculoides) can also result in microfilaremia. Although the type of microfilariae cannot be determined by microscopy alone, real-time PCR can reliably identify the infecting nematode species. Correct identification of the parasite is of major importance, as an infection with D. immitis requires antiparasitic therapy, whereas A. dracunculoides is thought to be a clinically irrelevant coincidental finding. The present case report describes a microfilaremic dog where the initial antigen test for D. immitis turned positive after heat treatment, whereas real-time PCR revealed that the microfilariae were A. dracunculoides (syn. Dipetalonema dracunculoides). Results A circa 5-year old, asymptomatic Spanish mastiff dog was referred for heartworm therapy because microfilariae were found via a screening blood test. The dog was recently imported to the Netherlands from Spain, where it had been a stray dog. Antigen tests on a plasma sample for D. immitis were performed with three different test kits, which all turned out to be negative. However, heat treatment of two of these samples were carried out and both of them led to a positive antigen test result. Real-time PCR showed that the circulating microfilariae belonged to A. dracunculoides species. Three administrations of moxidectin spot-on at monthly intervals resulted in a negative antigen and a negative Knott’s tests one month after the last treatment. Conclusions We conclude that heat treatment of initially negative blood samples for D. immitis could lead to false positive antigen test results if the dog is infected with A. dracunculoides.


PLoS ONE ◽  
2021 ◽  
Vol 16 (4) ◽  
pp. e0249972
Author(s):  
Oh Joo Kweon ◽  
Yong Kwan Lim ◽  
Hye Ryoun Kim ◽  
Yoojeong Choi ◽  
Min-Chul Kim ◽  
...  

We evaluated the diagnostic accuracy of two newly developed, point-of-care, rapid antigen tests (RATs) for detecting SARS-CoV-2, the AFIAS COVID-19 Ag and the ichromaTM COVID-19 Ag, and investigated antigen kinetics. A total of 200 serially collected nasopharyngeal (NP) specimens from 38 COVID-19 patients and 122 specimens from negative controls were analyzed. Diagnostic sensitivity and specificity were assessed in comparison to molecular test results and subdivided according to targeted genes (E, RdRP, and N) and days post-symptom onset (PSO). For the kinetics evaluation, cut-off-indices from serial NP specimens were used according to the number of days PSO. Both RATs showed sensitivity of 91.3‒100% for specimens with cycle threshold (Ct) < 25. The specificity of AFIAS was 98.7‒98.9% and that of ichromaTM was 100.0%. The kappa values of AFIAS and ichromaTM for the molecular testing of specimens with Ct < 25 (RdRP) were 0.97 and 1.00, respectively. The sensitivity of AFIAS and ichromaTM for all genes was lower for specimens collected at 8‒14 PSO than for those collected before 7-days PSO. The kinetics profiles showed that antigen levels gradually decreased from ≤ 7-days PSO to > 22-days PSO. Both RATs showed excellent specificity and acceptable sensitivity for NP specimens with higher viral loads and for specimens collected within 7-days PSO. Hence, they have the potential to become useful tools for the early detection of SARS-CoV-2. However, because of concerns about false negativity, RATs should be used in conjunction with molecular tests.


2021 ◽  
Author(s):  
Hiromichi Suzuki ◽  
Yusaku Akashi ◽  
Atsuo Ueda ◽  
Yoshihiko Kiyasu ◽  
Yuto Takeuchi ◽  
...  

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.


Author(s):  
Mary Kathryn Bohn ◽  
Giuseppe Lippi ◽  
Andrea R. Horvath ◽  
Rajiv Erasmus ◽  
Matthias Grimmler ◽  
...  

Abstract With an almost unremittent progression of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infections all around the world, there is a compelling need to introduce rapid, reliable, and high-throughput testing to allow appropriate clinical management and/or timely isolation of infected individuals. Although nucleic acid amplification testing (NAAT) remains the gold standard for detecting and theoretically quantifying SARS-CoV-2 mRNA in various specimen types, antigen assays may be considered a suitable alternative, under specific circumstances. Rapid antigen tests are meant to detect viral antigen proteins in biological specimens (e.g. nasal, nasopharyngeal, saliva), to indicate current SARS-CoV-2 infection. The available assay methodology includes rapid chromatographic immunoassays, used at the point-of-care, which carries some advantages and drawbacks compared to more conventional, instrumentation-based, laboratory immunoassays. Therefore, this document by the International Federation for Clinical Chemistry and Laboratory Medicine (IFCC) Taskforce on COVID-19 aims to summarize available data on the performance of currently available SARS-CoV-2 antigen rapid detection tests (Ag-RDTs), providing interim guidance on clinical indications and target populations, assay selection, and evaluation, test interpretation and limitations, as well as on pre-analytical considerations. This document is hence mainly aimed to assist laboratory and regulated health professionals in selecting, validating, and implementing regulatory approved Ag-RDTs.


2021 ◽  
Author(s):  
Yoshihiko Kiyasu ◽  
Masato Owaku ◽  
Yusaku Akashi ◽  
Yuto Takeuchi ◽  
Kenji Narahara ◽  
...  

Introduction Smart Gene is a point-of-care (POC)-type automated molecular testing platform that can be performed with 1 minute of hands-on-time. Smart Gene SARS-CoV-2 is a newly developed Smart Gene molecular assay for the detection of SARS-CoV-2. The analytical and clinical performance of Smart Gene SARS-CoV-2 has not been evaluated. Methods Nasopharyngeal and anterior nasal samples were prospectively collected from subjects referred to the local PCR center from March 25 to July 5, 2021. Two swabs were simultaneously obtained for the Smart Gene SARS-CoV-2 assay and the reference real-time RT-PCR assay, and the results of Smart Gene SARS-CoV-2 were compared to the reference real-time RT-PCR assay. Results Among a total of 1150 samples, 68 of 791 nasopharyngeal samples and 51 of 359 anterior nasal samples were positive for SARS-CoV-2 in the reference real-time RT-PCR assay. In the testing of nasopharyngeal samples, Smart Gene SARS-CoV-2 showed the total, positive and negative concordance of 99.2% (95% confidence interval [CI]: 98.4–99.7%), 94.1% (95% CI: 85.6–98.4%) and 99.7% (95% CI: 99.0–100%), respectively. For anterior nasal samples, Smart Gene SARS-CoV-2 showed the total, positive and negative concordance of 98.9% (95% CI: 97.2–99.7%), 98.0% (95% CI: 89.6–100%) and 99.0% (95% CI: 97.2–99.8%), respectively. In total, 5 samples were positive in the reference real-time RT-PCR and negative in Smart Gene SARS-CoV-2, whereas 5 samples were negative in the reference real-time RT-PCR and positive in Smart Gene SARS-CoV-2. Conclusion Smart Gene SARS-CoV-2 showed sufficient analytical performance for the detection of SARS-CoV-2 in nasopharyngeal and anterior nasal samples.


2021 ◽  
Author(s):  
Yoko Kurihara ◽  
Yoshihiko Kiyasu ◽  
Yusaku Akashi ◽  
Yuto Takeuchi ◽  
Kenji Narahara ◽  
...  

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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