scholarly journals Discordant SARS-CoV-2 PCR and Rapid Antigen Test Results When Infectious: A December 2021 Occupational Case Series

2022 ◽  
Author(s):  
Blythe J Adamson ◽  
Robby Sikka ◽  
Anne L Wyllie ◽  
Prem K Premsrirut
Keyword(s):  
Viral Load ◽  
High Risk ◽  
Diagnostic Tests ◽  
Case Series ◽  
Infectious Period ◽  
Test Results ◽  
Epidemiological Investigation ◽  
Antigen Test ◽  
Antigen Tests

The performance of Covid-19 diagnostic tests must continue to be reassessed with new variants of concern. The objective of this study was to describe the discordance in saliva SARS-CoV-2 PCR and nasal rapid antigen test results during the early infectious period. We identified a high-risk occupational case cohort of 30 individuals with daily testing during an Omicron outbreak in December 2021. Based on viral load and transmissions confirmed through epidemiological investigation, most Omicron cases were infectious for several days before being detectable by rapid antigen tests.

scholarly journals Rapid Tests for the Diagnosis of Viral Infections

2021 ◽  
Vol 96 (5) ◽  
pp. 415-420
Author(s):  
Hyun Soo Kim
Keyword(s):  
Nucleic Acid ◽  
Diagnostic Tests ◽  
Viral Infections ◽  
Rapid Test ◽  
Test Results ◽  
Test Items ◽  
Rapid Tests ◽  
Antigen Tests ◽  
Antibody Tests ◽  
Rapid Antibody

Rapid and accurate diagnostic tests for viral infections are essential for diagnosis, treatment, and patient isolation. Various rapid nucleic acid tests, rapid antigen tests, and rapid antibody tests have been developed and used to diagnose viral infections. In this paper, the types and characteristics of various rapid viral tests currently used in Korea, test items, and considerations when interpreting rapid test results are described.

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 Comparison of Antigen Tests and qPCR in Rapid Diagnostics of Infections Caused by SARS-CoV-2 Virus

Viruses ◽  
2021 ◽  
Vol 14 (1) ◽  
pp. 17
Author(s):  
Adrianna Klajmon ◽  
Aldona Olechowska-Jarząb ◽  
Dominika Salamon ◽  
Agnieszka Sroka-Oleksiak ◽  
Monika Brzychczy-Włoch ◽  
...  
Keyword(s):  
Quantitative Polymerase Chain Reaction ◽  
Molecular Techniques ◽  
Nucleic Acid Amplification ◽  
Laboratory Diagnostics ◽  
Test Results ◽  
Rapid Diagnostics ◽  
Antigen Test ◽  
Qualified Personnel ◽  
Replication Phase ◽  
Antigen Tests

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.

scholarly journals Role of Rapid Antigen Test in the Diagnosis of COVID-19 in India

2020 ◽  
pp. 77-80
Author(s):  
Aroop Mohanty ◽  
Ankita Kabi ◽  
Subodh Kumar ◽  
Vivek Hada
Keyword(s):  
Diagnostic Tests ◽  
Early Stage ◽  
The United States ◽  
Antigen Test ◽  
Rt Pcr ◽  
Is Development ◽  
Detection And Diagnosis ◽  
Antigen Tests ◽  
Spread Of Infection

In the current world scenario where we are seeing of an alarming increase in the number of SARS-CoV-2 infections, it is necessary that in addition to RT-PCR assays, there is development and standardization of other rapid and efficient diagnostic tests. In relation to the total number of confirmed cases, India ranks second only behind the United States and according to forecasts it will not be long before it reaches the first place. As in developing countries, such as India, it is difficult to implement molecular biology facilities in all centres, the creation of rapid antigen tests is increasingly common in the detection and diagnosis of cases of COVID-19 in an early stage limiting the spread of infection.”

scholarly journals Application of a Serial Antigen Based Testing Strategy for SARS-CoV-2 and Student Adherence in a University Setting, Wisconsin — October–November 2020

2021 ◽  
Author(s):  
John Paul Bigouette ◽  
Laura Ford ◽  
Ian Pray ◽  
Kimberly Langolf ◽  
Juliana Kahrs ◽  
...  
Keyword(s):  
Male Students ◽  
Test Results ◽  
Antigen Test ◽  
Testing Strategy ◽  
Rt Pcr ◽  
Testing Strategies ◽  
Serial Testing ◽  
Polymerase Chain ◽  
Antigen Tests ◽  
University Setting

Abstract Background Serial SARS-CoV-2 testing has been implemented at institutions of higher education (IHEs) and other settings. Testing strategies can include algorithms specifying confirmatory reverse transcription polymerase chain reaction (RT-PCR) testing after an antigen test. It is unknown how testing strategies perform detecting SARS-CoV-2, including individual adherence to serial testing requirements. Methods Student serial testing adherence was defined as completing ≥80% of weekly tests from October 5–November 14, 2020 and evaluated using logistic regression. Medical records were reviewed for all positive antigen test encounters and 10% of daily negative antigen test encounters during October 19–November 30, 2020. Results were used to estimate the proportion of individuals requiring only antigen tests, requiring and completing RT-PCR testing, and associated costs of tests. Results Two-thirds (66.5%; 1,166/1,754) of eligible on-campus students adhered to weekly testing; female students were more adherent (adjusted odds ratio [aOR]:2.07, 95% CI:1.66–2.59) than male students. Of all antigen test encounters, 11.5% (1,409/12,305) reported >1 COVID-19 symptoms. Of non-COVID-19 exposed antigen test encounters, 88% (10,386/11,769) did not require confirmatory RT-PCR testing. Only 28% (390/1,387) of testing encounters had an associated recommended confirmatory RT-PCR test performed. We estimated the testing strategy captured 61% (235/389) of predicted RT-PCR positive specimens. Conclusions At this IHE, most students voluntarily adhered to serial testing. The majority of antigen test results did not require confirmatory RT-PCR testing, but when required, most students did not obtain it. Including strategies to increase the proportion of individuals obtaining indicated confirmatory testing might improve the testing program’s performance.

scholarly journals Performance of antigenic detection of SARS-CoV-2 in nasopharyngeal samples

2021 ◽  
Author(s):  
Catalina Lunca ◽  
Cristian Cojocaru ◽  
Irina Luciana Gurzu ◽  
Florin Dumitru Petrariu ◽  
Elena Cojocaru
Keyword(s):  
Virus Detection ◽  
Protein Detection ◽  
Protein S ◽  
Screening Tests ◽  
Test Results ◽  
Antigen Test ◽  
Qrt Pcr ◽  
Qualitative Detection ◽  
Antigen Tests ◽  
Pcr Test

Objectives: SARS-CoV-2 virus detection on nasopharyngeal specimens to infected individuals has become a challenge for the COVID-19 pandemic outbreak. We aim at comparing the performance of antigenic detection of SARS-CoV-2 in nasopharyngeal samples via an immunochromatographic method to molecular detection via qRT-PCR. Materials and Methods: 47 nasopharyngeal exudates were collected from suspicious COVID-19 cases. The samples were performed both via the qualitative immuno-chromatographic method for S protein detection in the SARS-CoV-2 structure, using fluorescent labelled anti-protein S antibodies and via qRT-PCR test for the qualitative detection of the screening gene E and the specific ORF1ab region of the RNA-SARS-CoV-2. Results: There was a fair correlation between the positive antigen tests and the positive PCR assays measured through threshold cycle ORF1ab region (Ct orf). A better correlation was obtained between the antigen test results and the Ct orf when including patients with Ct orf below 25. Conclusions: Using antigen tests as screening tests is useful on symptomatic persons during the viral replication period, therefore during the contagious period. A positive test shows a high predictive value for infection, while a negative antigen test result via immuno-chromatography must be confirmed by a qRT-PCR test.

scholarly journals Diagnostic accuracy of rapid antigen tests in asymptomatic and presymptomatic close contacts of individuals with confirmed SARS-CoV-2 infection: cross sectional study

BMJ ◽  
2021 ◽  
pp. n1676
Author(s):  
Ewoud Schuit ◽  
Irene K Veldhuijzen ◽  
Roderick P Venekamp ◽  
Wouter van den Bijllaardt ◽  
Suzan D Pas ◽  
...  
Keyword(s):  
Viral Load ◽  
Cross Sectional Study ◽  
Antigen Test ◽  
Sectional Study ◽  
Rt Pcr ◽  
Cross Sectional ◽  
Predictive Values ◽  
Test Sensitivity ◽  
Antigen Tests ◽  
Close Contacts

Abstract Objective To assess the diagnostic test accuracy of two rapid antigen tests in asymptomatic and presymptomatic close contacts of people with SARS-CoV-2 infection on day 5 after exposure. Design Prospective cross sectional study. Setting Four public health service covid-19 test sites in the Netherlands. Participants 4274 consecutively included close contacts (identified through test-and-trace programme or contact tracing app) aged 16 years or older and asymptomatic for covid-19 when requesting a test. Main outcome measures Sensitivity, specificity, and positive and negative predictive values of Veritor System (Beckton Dickinson) and Biosensor (Roche Diagnostics) rapid antigen tests, with reverse-transcriptase polymerase chain reaction (RT-PCR) testing as reference standard. The viral load cut-off above which 95% of people with a positive RT-PCR test result were virus culture positive was used as a proxy of infectiousness. Results Of 2678 participants tested with Veritor, 233 (8.7%) had a RT-PCR confirmed SARS-CoV-2 infection of whom 149 were also detected by the rapid antigen test (sensitivity 63.9%, 95% confidence interval 57.4% to 70.1%). Of 1596 participants tested with Biosensor, 132 (8.3%) had a RT-PCR confirmed SARS-CoV-2 infection of whom 83 were detected by the rapid antigen test (sensitivity 62.9%, 54.0% to 71.1%). In those who were still asymptomatic at the time of sampling, sensitivity was 58.7% (51.1% to 66.0%) for Veritor (n=2317) and 59.4% (49.2% to 69.1%) for Biosensor (n=1414), and in those who developed symptoms were 84.2% (68.7% to 94.0%; n=219) for Veritor and 73.3% (54.1% to 87.7%; n=158) for Biosensor. When a viral load cut-off was applied for infectiouness (≥5.2 log10 SARS-CoV-2 E gene copies/mL), the overall sensitivity was 90.1% (84.2% to 94.4%) for Veritor and 86.8% (78.1% to 93.0%) for Biosensor, and 88.1% (80.5% to 93.5%) for Veritor and 85.1% (74.3% to 92.6%) for Biosensor, among those who remained asymptomatic throughout. Specificities were >99%, and positive and negative predictive values were >90% and >95%, for both rapid antigen tests in all analyses. Conclusions The sensitivities of both rapid antigen tests in asymptomatic and presymptomatic close contacts tested on day 5 onwards after close contact with an index case were more than 60%, increasing to more than 85% after a viral load cut-off was applied as a proxy for infectiousness.

An Informative Review on screening of COVID-19 (SARS-COVID-II)

2021 ◽  
pp. 259-265
Author(s):  
Nensi Raytthatha ◽  
Isha Shah ◽  
Jigar Vyas ◽  
Umesh Upadhyay
Keyword(s):  
High Risk ◽  
Severe Acute Respiratory Syndrome ◽  
Diagnostic Tests ◽  
Risk Groups ◽  
Nucleic Acid Amplification ◽  
Design Development ◽  
Reverse Transcription Pcr ◽  
In Vitro Diagnostic ◽  
Antigen Tests

Severe acute respiratory syndrome coronavirus 2(SARS-CoV-2) is a highly transmissible and pathogenic coronavirus that emerged in late 2019 and has caused a pandemic of acute respiratory disease, named ‘coronavirus disease 2019’ (COVID-19), which threatens human health and public safety. The disease caused by SARS‐CoV‐2, coronavirus disease 2019 (COVID‐19), presents flu‐like symptoms which can become serious in high‐risk individuals. During the early phase of the coronavirus (COVID-19) pandemic, design, development, validation, verification and implementation of diagnostic tests were actively conveyed by a large number of diagnostic test manufacturers. In this Review, we give an outline of the crucial role of diagnostic tests during the first world-wide indication of COVID-19. The severe acute respiratory syndrome coronavirus 2(SARS-CoV-2) and its associated coronavirus (COVID-19) pandemic has demanded rapid up scaling of in-vitro diagnostic assays to enable mass screening and testing of high-risk groups. To encounter the exponential demand in testing, there has been an expedite development of both molecular and serological assays across a superfluity of manifestos. The adjacent review discusses the current information on these modalities, including nucleic acid amplification tests, direct viral antigen tests. In the analytic stage, real-time reverse transcription-PCR (RT-PCR) assays remain the molecular test of choice for the etiologic diagnosis of SARS-CoV-2.

scholarly journals Association between viral load and positivization time of a SARS-CoV-2 rapid antigen test in routine nasopharyngeal specimens

2021 ◽  
Author(s):  
Gian Luca Salvagno ◽  
Brandon Michael Henry ◽  
Simone De Nitto ◽  
Laura Pighi ◽  
Giuseppe Lippi
Keyword(s):  
Viral Load ◽  
Diagnostic Testing ◽  
Area Under The Curve ◽  
High Viral Load ◽  
Antigen Test ◽  
Potential Association ◽  
Antigen Tests ◽  
Antigen Testing ◽  
Spearman’S Correlation ◽  
Positive Results

Abstract Background: Rapid SARS-CoV-2 antigen tests are potentially useful tools for screening carriers with high viral load. This study was aimed to assess the potential association between viral load and positivization time of a manual SARS-CoV-2 commercial antigen test in routine nasopharyngeal specimens. Methods: In a sample of subjects undergoing routine diagnostic testing, SARS-CoV-2 positivity of nasopharyngeal samples was assayed with both molecular (Altona Diagnostics RealStar SARS-CoV-2 RT-PCR Kit) and antigenic (Roche SARS-CoV-2 Rapid Antigen Test) tests. Positivization time of rapid antigen test was correlated and compared with viral load expressed as mean of SARS-CoV-2 E/S genes cycle threshold (Ct) values.Results: The study sample consisted of 106 patients (median age 48 years, 55 women) with positive results of rapid SARS-CoV-2 antigen testing. A highly significant Spearman’s correlation was found between mean SARS-CoV-2 E/S genes Ct values and positivization time of manual antigen test (r= 0.70; p<0.001). The positivization time of rapid SARS-CoV-2 antigen test displayed an area under the curve of 0.82 (95%CI, 0.74-0.89) for predicting nasopharyngeal samples with high viral load (i.e., mean Ct <20). A positivization time cut-off of 32 sec had 94.9% sensitivity and 58.2% specificity for detecting specimens with high viral load. The overall agreement between mean Ct value <20 and positivization time <32 sec was 70.8%.Conclusions: Positivization time of rapid SARS-CoV-2 antigen tests may provide easy and rapid information on viral load, thus making this type of manual assay potentially suitable for quick and reliable detection and isolation of super-carries.

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

2021 ◽  
Author(s):  
Olivia Almendares ◽  
Jessica L. Prince-Guerra ◽  
Leisha D. Nolen ◽  
Jayleen K.L. Gunn ◽  
Ariella P. Dale ◽  
...  
Keyword(s):  
Real Time ◽  
Point Of Care ◽  
Exposure Period ◽  
Rapid Identification ◽  
Nucleic Acid Amplification ◽  
Test Results ◽  
Antigen Test ◽  
Viral Culture ◽  
Pima County ◽  
Antigen Tests

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.

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