scholarly journals Performance characteristics of a rapid SARS-CoV-2 antigen detection assay at a public plaza testing site in San Francisco

2020 ◽  
Author(s):  
Genay Pilarowski ◽  
Paul Lebel ◽  
Sara Sunshine ◽  
Jamin Liu ◽  
Emily Crawford ◽  
...  
Keyword(s):  
Viral Load ◽  
San Francisco ◽  
High Viral Load ◽  
Performance Characteristics ◽  
Viral Rna ◽  
Antigen Test ◽  
Rt Pcr ◽  
Detection Assay ◽  
Community Transmission ◽  
Testing Site

ABSTRACTWe evaluated the performance of the Abbott BinaxNOW™ Covid-19 rapid antigen test to detect virus among persons, regardless of symptoms, at a public plaza site of ongoing community transmission. Titration with cultured clinical SARS-CoV-2 yielded a human observable threshold between 1.6×104-4.3×104 viral RNA copies (cycle threshold (Ct) of 30.3-28.8 in this assay). Among 878 subjects tested, 3% (26/878) were positive by RT-PCR, of which 15/26 had a Ct<30, indicating high viral load. 40% (6/15) of Ct<30 were asymptomatic. Using this Ct<30 threshold for Binax-CoV2 evaluation, the sensitivity of the Binax-CoV2 was 93.3% (14/15), 95% CI: 68.1-99.8%, and the specificity was 99.9% (855/856), 95% CI: 99.4-99.9%.

scholarly journals Performance characteristics of a rapid SARS-CoV-2 antigen detection assay at a public plaza testing site in San Francisco

2021 ◽  
Author(s):  
Genay Pilarowski ◽  
Paul Lebel ◽  
Sara Sunshine ◽  
Jamin Liu ◽  
Emily Crawford ◽  
...  
Keyword(s):  
Viral Load ◽  
San Francisco ◽  
High Viral Load ◽  
Performance Characteristics ◽  
Viral Rna ◽  
Antigen Test ◽  
Rt Pcr ◽  
Detection Assay ◽  
Community Transmission ◽  
Testing Site

Abstract We evaluated the performance of the Abbott BinaxNOW TM Covid-19 rapid antigen test (Binax-CoV2) to detect virus among persons, regardless of symptoms, at a public plaza site of ongoing community transmission. Titration with cultured SARS-CoV-2 yielded a human observable threshold between 1.6x10 4-4.3x10 4 viral RNA copies (cycle threshold (Ct) of 30.3-28.8). Among 878 subjects tested, 3% (26/878) were positive by RT-PCR, of which 15/26 had Ct&lt;30, indicating high viral load. 40% (6/15) of Ct&lt;30 were asymptomatic. Using this Ct&lt;30 threshold for Binax-CoV2 evaluation, the sensitivity of Binax-CoV2 was 93.3% (14/15), 95% CI: 68.1-99.8%, and the specificity was 99.9% (855/856), 95% CI: 99.4-99.9%.

scholarly journals Direct Comparison of SARS Co-V-2 Nasal RT- PCR and Rapid Antigen Test (BinaxNOWTM) at a Community Testing Site During an Omicron Surge

2022 ◽  
Author(s):  
John Schrom ◽  
Carina Marquez ◽  
Genay Pilarowski ◽  
Grace Wang ◽  
Anthea Mitchell ◽  
...  
Keyword(s):  
San Francisco ◽  
High Viral Load ◽  
Antigen Test ◽  
Rt Pcr ◽  
Repeat Testing ◽  
Single Antigen ◽  
Testing Site ◽  
Antigen Testing ◽  
Test Result ◽  
Community Site

In 731 persons seeking COVID-19 testing at a walk-up San Francisco community site in January 2022, simultaneous nasal rapid antigen testing (BinaxNOWTM) and RT-PCR testing was performed. There were 296 (40.5%) positive tests by RT-PCR; 97% of a random sample were the omicron variant. Sensitivity of a single antigen test was 95.2% (95% CI 92-98%); 82.1% (95% CI 77-87%) and 65.2% (95% CI 60-70%) for Ct threshold of < 30, < 35 and no threshold, respectively. A single BinaxNowTM rapid antigen test detected 95% of high viral load omicron cases from nasal specimens. As currently recommended, repeat testing should be done for high- risk persons with an initial negative antigen test result.

scholarly journals Clinical evaluation of the Roche/SD Biosensor rapid antigen test with symptomatic, non-hospitalized patients in a municipal health service drive-through testing site

2020 ◽  
Author(s):  
Zsὁfia Iglὁi ◽  
Jans Velzing ◽  
Janko van Beek ◽  
David van de Vijver ◽  
Georgina Aron ◽  
...  
Keyword(s):  
Viral Load ◽  
Rapid Test ◽  
Contact Tracing ◽  
Gene Copy ◽  
Nasopharyngeal Swab ◽  
List Type ◽  
Antigen Test ◽  
Rt Pcr ◽  
Outbreak Management ◽  
Testing Site

AbstractBackgroundRapid detection of infectious individuals is essential in stopping the further spread of SARS-CoV-2. Although rapid antigen test is not as sensitive as the gold standard RT-PCR, the time to result is decreased by day(s), strengthening the effectiveness of contact tracing.MethodsThe Roche/SD Biosensor lateral flow antigen rapid test was evaluated in a mild symptomatic population at a large drive through testing site. A second nasopharyngeal swab was directly tested with the rapid test on site and results were compared to RT-PCR and virus culture. Date of onset and symptoms were analysed using data from a clinical questionnaire.ResultsWe included 970 persons with complete data. Overall sensitivity and specificity were 84.9% (CI95% 79.1-89.4) and 99.5% (CI95% 98.7-99.8) which translated into a positive predictive value of 97.5% (CI95% 94.0-99.5) under the current regional PCR positivity of 19.2%. Sensitivity for people with high loads of viral RNA (ct <30, 2.17E+05 E gene copy/ml) and who presented within 7 days since symptom onset increased to 95.8% (CI95% 90.5-98.2). Band intensity and time to result correlated strongly with viral load thus strong positive bands could be read before the recommended time. Around 98% of all viable specimen with ct <30 were detected successfully indicating that the large majority of infectious people can be captured with this test.ConclusionAntigen rapid tests can detect mildly symptomatic cases in the early phase of disease thereby identifying the most infectious individuals. Using this assay can have a significant value in the speed and effectiveness of SARS-CoV-2 outbreak management.SummaryPeople with early onset and high viral load were detected with 98.2% sensitivity.97% of individuals in which virus could be cultured were detected by the rapid test.This test is suitable to detect mild symptomatic cases.

scholarly journals Comparison of the quantitative DiaSorin Liaison antigen test to RT-PCR for the diagnosis of COVID-19 in symptomatic and asymptomatic outpatients

2021 ◽  
Author(s):  
Stefanie Lefever ◽  
Christophe Indevuyst ◽  
Lize Cuypers ◽  
Klaas Dewaele ◽  
Nicolas Yin ◽  
...  
Keyword(s):  
Viral Load ◽  
Confidence Interval ◽  
Sensitivity And Specificity ◽  
High Viral Load ◽  
Antigen Test ◽  
Rt Pcr ◽  
Antigen Concentration ◽  
General Practioner ◽  
Asymptomatic Individuals

Background:We evaluated the quantitative DiaSorin Liaison SARS-CoV-2 antigen test in symptomatic and asymptomatic individuals consulting their general practioner (GP) during a period of stable intense virus circulation (213/100,000 habitants per day). Methods:Left-over RT-PCR positive (n=204) and negative (n=210) nasopharyngeal samples were randomly selected among fresh routine samples collected from patients consulting their GP. Samples were tested on Liaison XL according to the manufacturer’s instructions. Equivocal results were considered positive. Results:Overall sensitivity and specificity of the Liaison antigen test compared to RT-PCR were 67.7% [95% confidence interval (CI): 60.9%-73.7%] and 100% [CI: 97.8%-100%]. Sensitivity in samples with a viral load ≥105, ≥104 and ≥103 copies/mL was 100% [CI: 96.3%-100.0%], 96.5% [CI: 91.8%-98.7%] and 87.4% [CI: 81.3%-91.5%], respectively. All samples ≤103 copies/mL were antigen negative. The ratio of antigen concentration to viral load in samples ≥103 copies/mL was comparable in symptomatic and asymptomatic individuals (p=0.58). The proportion of RT-PCR positive participants with a high viral load (≥105 copies/mL) was not significantly higher in symptomatic than in asymptomatic participants (63.9% [CI: 54.9%-72.0%] vs. 51.9% [CI: 41.1%-62.6%], p=0.11), but the proportion of participants with a low viral load (<103 copies/mL) was significantly higher in asymptomatic than in symptomatic RT-PCR positive participants (35.4% [CI: 25.8%-46.4%] vs. 14.3% [CI: 9.0%-21.8%], p<0.01). Conclusions:Sensitivity and specificity in samples with a viral load ≥104 copies/mL was 96.5% and 100%. The correlation of antigen concentration with viral load was comparable in symptomatic and asymptomatic individuals.

scholarly journals Prolonged Detection of SARS CoV2 RNA in Extracellular Vesicles in Nasal Swab RT-PCR Negative Patients

2021 ◽  
Author(s):  
P Debishree Subudhi ◽  
Sheetalnath Rooge ◽  
Swati Thangriyal ◽  
Reshu Aggarwal ◽  
Ekta Gupta ◽  
...  
Keyword(s):  
Endothelial Cells ◽  
Viral Load ◽  
Liver Disease ◽  
Chronic Liver Disease ◽  
Extracellular Vesicles ◽  
Nasal Swab ◽  
High Viral Load ◽  
Chronic Liver ◽  
Rt Pcr ◽  
Route Of Transmission

Background: There is a prolonged RT PCR positivity seen in COVID-19 infected patients up to 2 to 3 months. It is assumed that this virus is usually non-infective but there are hardly any study on the reactivation of this virus within the respiratory tract. We aim to investigate the presence of viral particles inside Extracellular vesicles (EV) and its role in underlying liver disease patients. Methods: SARS CoV2 nasal and throat swab RT-PCR positive n=78 {n=24(66.6%) chronic liver disease (CLD); n=52 (81.3%) non liver disease} n=5 RT PCR negative subjects (HC) were studied. SARS CoV2 patients were also followed up for day (d) 7, 14 and 28. Nasal swab [collected in viral transport media (VTM)] and plasma samples were investigated at each time point. Extracellular vesicles were isolated using differential ultracentrifugation. SARS CoV2 RNA was measured using qRT-PCR by Altona Real Star kit. Cellular origin of EV was confirmed using epithelial cells (Epcam+ CK19+ CDh1+), endothelial cells (CD31+CD45-), and hepatocytes (ASGPR+) surface markers by Flow cytometry. Results: The COVID19 patients {Mean age 54±23 years; 41 males} were having severity between moderate to severe. In patients with cirrhosis, the most common aetiology of liver disease was alcohol (MELD 22±8). In baseline RT-PCR positive patients, SARS-CoV2 RNA inside the EV was present in 64/74 (82%) patients with comparable viral load between VTM and EV (mean 1/CT 0.033±0.005 vs. 1/CT 0.029±0.014, p=ns). On follow-up at day 7, of the 24 patients negative for COVID19, 10 (41%) had persistence of virus in the EV (1/CT 0.028±0.004) and on day 14, 14 of 40 (35%) negative RT-PCR had EVs with SARS CoV2 RNA (1/CT 0.028±0.06). The mean viral load decreased at day7 and day14 in nasal swab from baseline (p=0.001) but not in EV. SARS-CoV2 RNA otherwise undetectable in plasma, was found to be positive in EV in 12.5% of COVID19 positive patients. Interestingly, significantly prolonged and high viral load was found in EV at day 14 in CLD COVID19 patients compared to COVID19 alone (p=0.002). The high cellular injury was seen in CLD COVID19 infected patients with significant high levels of EV associated with endothelial cells and hepatocytes than COVID19 alone (p=0.004; 0.001). Conclusion: Identification of SARS-CoV2 RNA in EV, in RT-PCR negative patients indicates persistence of infection for and likely recurrence of the infection. It is suggestive of another route of transmission as EV harbour SARS CoV2 RNA. EV associated RNA may determine the ongoing inflammation and clinical course of subjects with undetectable SARS-CoV2 virus and this may also have relevance in management of chronic liver disease patients.

scholarly journals Rapid Diagnosis of SARS-CoV-2 Pneumonia on Lower Respiratory Tract Specimens

2021 ◽  
Author(s):  
Vanessa De Pace ◽  
Patrizia Caligiuri ◽  
Valentina Ricucci ◽  
Nicola Nigro ◽  
Barbara Galano ◽  
...  
Keyword(s):  
Intensive Care ◽  
Viral Load ◽  
Respiratory Tract ◽  
Intensive Care Units ◽  
Lower Respiratory Tract ◽  
Clinical Decision Making ◽  
High Viral Load ◽  
Rt Pcr ◽  
Predictive Values ◽  
Rapid Pcr

Abstract Background: The ongoing pandemic of SARS-CoV-2 requires the availability of accurate and rapid diagnostic tests, especially in some clinical settings like emergency and intensive care units. The objective of this study was to evaluate the diagnostic performances of rapid PCR kit Vivalytic SARS-CoV-2 in lower respiratory tract (LRT) specimens.Methods: A consecutive sample of LRT specimens (bronchoalveolar lavage and bronchoaspirates) was collected from Intensive Care Units of San Martino Hospital (Genoa, Italy) between November 2020 and January 2021. All samples were tested in RT-PCR by using Allplex™ SARS-CoV-2 assay (Seegene Inc., South Korea). Based on RT-PCR results, specimens were categorized into negative, positive with high viral load [cycle threshold (Ct) ≤30] and positive with low viral load (Ct of 31–35). A quota 1:1:1 sampling was used to achieve a sample size of 75. Then, all specimens were tested in the rapid PCR assay Vivalytic SARS-CoV-2 (Bosch Healthcare Solutions GmbH, Germany). The diagnostic performance of the rapid PCR against RT-PCR was assessed through calculation of accuracy, Cohen’s κ, sensitivity, specificity and expected positive (PPV) and negative (NPV) predictive values.Results: The overall diagnostic accuracy of the Vivalytic SARS-CoV-2 was 97.3% (95% CI: 90.9–99.3%) with an excellent Cohen’s κ of 0.94 (95% CI: 0.72–1). The sensitivity and specificity were 96% (95% CI: 86.5–98.9%) and 100% (95% CI: 86.7–100%), respectively. Samples with high viral loads had a sensitivity of 100% (Table 1). The distributions of E gene Ct values were similar (Wilcoxon’s test: P=0.070) with medians of 35 (IQR: 25–36) and 35 (IQR: 25–35), respectively (Figure 1). NPV and PPV was 92.6% and 100%, respectively.Conclusions: This study shows Vivalytic SARS-CoV-2 can be used following the sample liquefaction on LRT specimens. It’s a feasible and highly accurate molecular procedure especially in high viral load samples. This assay allows having a result in about 40 min and therefore may accelerate the clinical decision making in urgent/emergency situations.

scholarly journals Viral RNA Patterns and High Viral Load Reliably Define Oropharynx Carcinomas with Active HPV16 Involvement

2012 ◽  
Vol 72 (19) ◽  
pp. 4993-5003 ◽  
Author(s):  
Dana Holzinger ◽  
Markus Schmitt ◽  
Gerhard Dyckhoff ◽  
Axel Benner ◽  
Michael Pawlita ◽  
...  
Keyword(s):  
Viral Load ◽  
High Viral Load ◽  
Viral Rna

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 Viral load and antibody levels in patients with COVID-19

2021 ◽  
Vol 8 (3) ◽  
pp. 010-018
Author(s):  
Iva Christova ◽  
Iva Trifonova ◽  
Teodora Gladnishka ◽  
Elena Dragusheva ◽  
Georgi Popov ◽  
...  
Keyword(s):  
Viral Load ◽  
High Viral Load ◽  
Igg Antibodies ◽  
Rt Pcr ◽  
Serum Samples ◽  
Weekly Basis ◽  
Specific Antibody Response ◽  
Viral Loads ◽  
Antibody Levels ◽  
Kinetics Of

Relations between viral load, antibody levels and COVID-19 severity are not well studied and results from such investigations are controversial. In this study, we investigated kinetics of viral load and antibody responses to SARS-CoV-2 in 20 patients with COVID-19 and analysed the association with disease severity. The patients were followed on weekly basis within the first month after the onset and then once per month for the next 4 months. Serum samples were tested for IgA, IgM, and IgG antibodies against SARS-CoV-2 using ELISA tests. SARS-CoV-2 viral load in nasopharyngeal swabs was measured by quantitative Realtime RT-PCR. For vast majority of the patients, the viral loads were at their highest levels at presentation and then declined gradually. Despite development of specific antibody response 7-11 days after the onset of COVID-19, SARS-CoV-2 RNA was still detected in nasopharyngeal swabs of most of the patients. There was no direct link between viral load and severity of COVID-19: some of mild and some of severe cases started with a high viral load. There was a relationship between the time from the onset of the disease and the viral load: the highest viral load was in the first days. In more severe cases, there was a tendency for slower reduction in viral load and longer detection of SARS-CoV-2 virus. Levels of the specific antibodies increased earlier and to higher levels and were present for longer time in patients with more severe manifestations of COVID-19 than in those with milder disease.

scholarly journals Characteristics of children and antigen test performance at a SARS-CoV-2 community testing site

2021 ◽  
Author(s):  
Laura Ford ◽  
Melissa J. Whaley ◽  
Melisa M. Shah ◽  
Phillip P. Salvatore ◽  
Hannah E. Segaloff ◽  
...  
Keyword(s):  
Test Performance ◽  
Point Of Care ◽  
Lower Sensitivity ◽  
Antigen Test ◽  
Rt Pcr ◽  
Culture Methods ◽  
Viral Culture ◽  
Asymptomatic Children ◽  
Testing Site ◽  
Antigen Tests

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.

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