scholarly journals The sensitivity of SARS-CoV-2 antigen tests in the view of large-scale testing

2020 ◽  
Author(s):  
Pavel Drevinek ◽  
Jakub Hurych ◽  
Zdenek Kepka ◽  
Ales Briksi ◽  
Michal Kulich ◽  
...  
Keyword(s):  
Large Scale ◽  
Point Of Care ◽  
Rapid Test ◽  
Antigen Test ◽  
Repeated Testing ◽  
Diagnostic Pcr ◽  
Large Scale Testing ◽  
Oropharyngeal Swab ◽  
Antigen Tests ◽  
Low Sensitivity

AbstractObjectivesAntigen tests have recently emerged as an interesting alternative to SARS-CoV-2 diagnostic PCR, thought to be valuable especially for the screening of bigger communities. To check appropriateness of the antigen based testing, we determined sensitivity of two point-of-care antigen tests when applied to a cohort of COVID-19 symptomatic, COVID-19 asymptomatic and healthy persons.MethodsWe examined nasopharyngeal swabs with antigen test 1 (Panbio Covid-19 Ag Rapid Test, Abbott) and antigen test 2 (Standard F Covid-19 Ag FIA, SD Biosensor). An additional nasopharyngeal and oropharyngeal swab of the same individual was checked with PCR (Allplex SARS-nCoV-2, Seegene). Within a 4-day period in October 2020, we collected specimens from 591 subjects. Of them, 290 had COVID-19 associated symptoms.ResultsWhile PCR positivity was detected in 223 cases, antigen test 1 and antigen test 2 were found positive in 148 (sensitivity 0.664, 95% CI 0.599 - 0.722) and 141 (sensitivity 0.623, 95% CI 0.558 - 0.684) patients, respectively. When only symptomatic patients were analysed, sensitivity increased to 0.738 (95% CI 0.667 - 0.799) for the antigen test 1 and to 0.685 (95% CI 0.611 - 0.750) for the antigen test 2. The substantial drop in sensitivity to 12.9% (95% CI 0.067 - 0.234) was observed for samples with the PCR threshold cycle above > 30.ConclusionsLow sensitivity of antigen tests leads to the considerable risk of false negativity. It is advisable to implement repeated testing with high enough frequency if the antigen test is used as a frontline screening tool.

scholarly journals Reducing the Cost of Rapid Antigen Tests through Swab Pooling and Extraction in a Device

2021 ◽  
Author(s):  
Tim Berking ◽  
Sabrina G. Lorenz ◽  
Alexander Ulrich ◽  
Joachim Greiner ◽  
Clemens Richert
Keyword(s):  
Large Scale ◽  
Signal To Noise Ratio ◽  
Point Of Care ◽  
Positive Control ◽  
Extraction Buffer ◽  
Large Scale Testing ◽  
Antigen Tests ◽  
Set Up ◽  
Cost Of Materials ◽  
The Cost

AbstractThe COVID-19 pandemic places a significant stress on the viral testing capabilities of many countries. The value of rapid point-of-care (PoC) antigen tests is becoming increasingly clear, but implementing frequent large scale testing is costly. We have developed an inexpensive device for pooling swabs, extracting specimens, and detecting viral antigens with a commercial lateral flow assay detecting the nucleocapsid protein of SARS-CoV-2 as antigen. The holder of the device can be produced locally through 3D printing. The extraction and the elution can be performed with the entire set-up encapsulated in a transparent bag, minimizing the risk of infection for the operator. With 6 swabs holding approx. 0.1 mL specimen each and 0.35 mL extraction buffer, 43±6 % (n= 8) of the signal for an individual extraction of a positive control standard was obtained. Image analysis still showed a signal-to-noise ratio of ≥ 7 upon further eight-fold dilution. Our current total cost of materials is below $ 2 per tested person or 20% of our cost for an individual PoC test. These findings suggest that pooling can make frequent testing more affordable for schools, universities and other institutions, without decreasing sensitivity to an unacceptable level. Further validation of the method is required.

scholarly journals Testing Denmark: A Danish nationwide surveillance study of COVID-19

2021 ◽  
Author(s):  
Kamille Fogh ◽  
Jarl E Strange ◽  
Bibi FSS Scharff ◽  
Alexandra RR Eriksen ◽  
Rasmus B Hasselbalch ◽  
...  
Keyword(s):  
Large Scale ◽  
Point Of Care ◽  
Rapid Test ◽  
Physical Contact ◽  
Surveillance Study ◽  
Epidemiological Surveillance ◽  
Danish Population ◽  
Positive Polymerase Chain Reaction ◽  
Geographic Population ◽  
Associated Risk Factors

Background National data on the spread of SARS-CoV-2 infection and knowledge on associated risk factors are important for understanding the course of the pandemic. Testing Denmark is a national large-scale epidemiological surveillance study of SARS-CoV-2 in the Danish population. Methods Between September and October 2020, approximately 1.3 million of 5.8 million Danish citizens (age > 15 years) were randomly invited to fill in an electronic questionnaire covering COVID-19 exposures and symptoms. The prevalence of SARS-CoV-2 antibodies was determined by Point-of Care rapid Test (POCT) distributed to participants home addresses. Findings In total 318,552 participants (24.5% invitees) completed the questionnaire and provided the result of the POCT. Of these, 2,519 (0.79%) were seropositive (median age 55 years) and women were more often seropositive than men, interquartile range (IQR) 42-64, 40.2% males. Of participants with a prior positive Polymerase Chain Reaction (PCR) test (n=1,828), 29.1% were seropositive in the POCT. Seropositivity increased with age irrespective of sex. Elderly participants (>61 years) reported less symptoms and had less frequently been tested for SARS-CoV-2 compared to younger participants. Seropositivity was associated with physical contact with SARS-CoV-2 infected individuals (Risk ratio (RR) 7.43, 95% CI: 6.57-8.41) and in particular household members (RR 17.70, 95% CI: 15.60-20.10). Home care workers had a higher risk of seropositivity (RR 2.09 (95% CI: 1.58-2.78) as compared to office workers. Geographic population density was not associated to seropositivity. A high degree of compliance with national preventive recommendations was reported (e.g., > 80% use of face masks), but no difference was found between seropositive and seronegative participants. Interpretation This study provides insight into the immunity of the Danish population seven to eight months after the first COVID-19 case in Denmark. The seroprevalence was lower than expected probably due to a low sensitivity of the POCT used or due to challenges relating to the reading of test results. Occupation or exposure in local communities were major routes of infection. As elderly participants were more often seropositive despite fewer symptoms and less PCR tests performed, more emphasis should be placed on testing this age group.

Correlation of COVID-19 antigen test and CBNAAT results at a single tertiary care hospital in North India: an experience

2021 ◽  
Vol 8 (5) ◽  
pp. 2427
Author(s):  
Surbhi Gupta ◽  
Anju Shukla ◽  
Poonam Singh ◽  
Areena H. Siddiqui
Keyword(s):  
Tertiary Care Hospital ◽  
Point Of Care ◽  
Tertiary Care ◽  
Uttar Pradesh ◽  
Nucleic Acid Amplification ◽  
North India ◽  
Care Hospital ◽  
Antigen Test ◽  
Discordant Group ◽  
Antigen Tests

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.

scholarly journals Comparative Sensitivity of Rapid Antigen Tests for the Delta Variant (B.1.617.2) of SARS-CoV-2

Viruses ◽  
2021 ◽  
Vol 13 (11) ◽  
pp. 2183
Author(s):  
Yuko Sakai-Tagawa ◽  
Seiya Yamayoshi ◽  
Peter J. Halfmann ◽  
Yoshihiro Kawaoka
Keyword(s):  
Rapid Detection ◽  
Influenza A ◽  
Infectious Virus ◽  
Rapid Test ◽  
Rapid Diagnosis ◽  
Antigen Test ◽  
Detection Level ◽  
Test Kit ◽  
Low Levels ◽  
Antigen Tests

Rapid antigen tests (RATs) for COVID-19 based on lateral flow immunoassays are useful for rapid diagnosis in a variety of settings. Although many kinds of RATs are available, their respective sensitivity has not been compared. Here, we examined the sensitivity of 27 RATs available in Japan for the detection of the SARS-CoV-2 delta variant. All of the RATs tested detected the delta variant albeit with different sensitivities. Nine RATs (ESPLINE SARS-CoV-2, ALSONIC COVID-19 Ag, COVID-19 and Influenza A+B Antigen Combo Rapid Test, ImmunoArrow SARS-CoV-2, Fuji Dri-chem immuno AG cartridge COVID-19 Ag, 2019-nCoV Ag rapid detection kit, Saliva SARS-CoV-2(2019-nCoV) Antigen Test Kit, and Rabliss SARS-CoV-2 antigen detection kit COVID19 AG) showed superior sensitivity to the isolated delta variant. Although actual clinical specimens were not examined, the detection level of most of the RATs was 7500 pfu, indicating that individuals whose test samples contained less virus than that would be considered negative. Therefore, it is important to bear in mind that RATs may miss individuals shedding low levels of infectious virus.

scholarly journals An assessment of a rapid SARS-CoV-2 antigen test in Bangladesh

2021 ◽  
Author(s):  
Zannat Kawser ◽  
Mohabbat Hossain ◽  
Sara Suliman ◽  
Shahin Lockman ◽  
Jesse Gitaka ◽  
...  
Keyword(s):  
False Positive ◽  
Rapid Test ◽  
Field Evaluation ◽  
Ease Of Use ◽  
Large Field ◽  
Antigen Test ◽  
Rt Pcr ◽  
Rapid Antigen Detection Test ◽  
Antigen Tests ◽  
Asymptomatic Individuals

Early detection of SARS-CoV-2 infection is crucial to prevent the spread of the virus. In this study, we evaluated the performance of a commercial rapid antigen detection test, BD Veritor, and compared this (and another rapid test, Standard Q) against a gold-standard of nasopharyngeal (NP) swab tested by reverse transcription-polymerase chain reaction (RT-PCR) in prospectively recruited adults in Dhaka, Bangladesh. We compared the sensitivity and specificity of the two rapid antigen tests against RT-PCR results in 130 symptomatic and 130 asymptomatic adults. In addition, we evaluated the suitability and ease-of-use of the BD Veritor test in a subsample of study participants (n=42) and implementers (n=5). The sensitivity of the BD Veritor rapid antigen 66 test was 70% in symptomatic (95% confidence interval [CI]: 51-85%) and 87% (95% CI: 69-96%) in asymptomatic individuals with positive SARSCoV-2 RT-PCR, for overall sensitivity of 78% (95% CI: 66-88%). The sensitivity of the Standard Q rapid antigen test was 63% (95% CI: 44-69 80%) in symptomatic and 73% (95% CI: 54-87%) in asymptomatic individuals. One false positive in BD Veritor test (specificity 99.5) and no false positive in Standard Q tests were observed (specificity 100%). The BD Veritor rapid antigen test was 78% sensitive when compared with RT-PCR irrespective of the cycle threshold (Ct) levels in this evaluation in Bangladesh. The implementation evaluation data showed good acceptability in the field settings. This warrants large field evaluation as well as use of the rapid antigen test for quick assessment of SARS-CoV-2 for containment of epidemics in the country.

scholarly journals Nasopharyngeal Panbio COVID-19 antigen performed at point-of-care has a high sensitivity in symptomatic and asymptomatic patients with higher risk for transmission and older age

2021 ◽  
Author(s):  
Mar Masiá ◽  
Marta Fernández-González ◽  
Manuel Sánchez ◽  
Mar Carvajal ◽  
José Alberto García ◽  
...  
Keyword(s):  
Test Performance ◽  
Point Of Care ◽  
Rapid Test ◽  
High Sensitivity ◽  
Older Age ◽  
Antigen Test ◽  
Rt Pcr ◽  
Asymptomatic Patients ◽  
Clinical Scenarios ◽  
Nasal Swabs

Abstract Background Performance of point-of-care tests in different clinical scenarios and on different samples remains undetermined. We comprehensively evaluated the performance of the nasopharyngeal Panbio COVID-19 antigen Rapid-Test-Device. Method Prospective study including consecutive patients attending three primary care centers (PCC) and an emergency department. The antigen test was performed at point-of-care in nasopharyngeal and nasal swabs, and in saliva. Positive and negative percent agreement (PPA, NPA) were calculated with the RT-PCR assay as reference standard. Results Of 913 patients included, 296 (32.3%) were asymptomatic and 690 (75.6%) came from the PCC. Nasopharyngeal swabs were collected from 913, nasal swabs from 659, and saliva from 611 patients. RT-PCR was positive in 196 (21.5%) nasopharyngeal samples (NPS). Overall PPA (95% CI) in NPS was 60.5% (53.3-67.4), and it was lower in nasal swabs (44.7%) and saliva (23.1%). Test performance in NPS was largely dependent on the cycle threshold (Ct) in RT-PCR, with PPA of 94% for Ct≤25 and 80% for Ct<30. In symptomatic patients, the PPA was 95% for Ct≤25; 85% for Ct<30, and 89% for the symptom triad of fever, cough and malaise. Performance was also dependent on age, with PPA of 100% in symptomatic patients >50 years with Ct<25. In asymptomatic patients, the PPA was 86% for Ct<25. In all cases, NPA was 100%. Conclusion The nasopharyngeal Panbio COVID-19 antigen test performed at point-of-care has a good sensitivity in symptomatic patients with Ct<30 and older age. The test was useful to identify asymptomatic patients with lower Ct values.

scholarly journals Preliminary Results of Seroprevalence of SARS-CoV-2 at Community Clinics in Tokyo

2020 ◽  
Author(s):  
Morihito Takita ◽  
Tomoko Matsumura ◽  
Kana Yamamoto ◽  
Erika Yamashita ◽  
Kazutaka Hosoda ◽  
...  
Keyword(s):  
Point Of Care ◽  
Cross Reactivity ◽  
Igg Antibody ◽  
Community Clinics ◽  
Diagnostic Pcr ◽  
Point Of Care Test ◽  
Positive Rate ◽  
Specific Igg ◽  
Novel Coronavirus ◽  
Low Sensitivity

AbstractSerological evaluation with SARS-CoV-2 specific IgG antibody will be an alternative way to know the pandemic of novel coronavirus disease (COVID-19) if the capacity for diagnostic PCR test is limited. The point-of-care test to detect SARS-CoV-2 specific IgG antibody in peripheral blood (n =202) was performed in two community clinics in Tokyo, Japan. The overall positive rate of SRAS-CoV-2 IgG antibody was 5.9% (95% confidence interval[CI]: 3.1-10.1). Higher rate was observed for healthcare workers (n =55, 9.1 [3.0-20.0]). The limitation on antibody tests includes low sensitivity and potent cross-reactivity with the previous coronavirus. Robust healthcare policy to efficiently monitor COVID-19 spread is warranted in Tokyo.

scholarly journals Evaluation of Four Rapid Antigen Tests for Detection of SARS-CoV-2 virus

2021 ◽  
Vol 36 (5) ◽  
pp. e297-e297
Author(s):  
Sulaiman Al-Alawi ◽  
Hala Al-Hinai ◽  
Nawal Al-Kindi ◽  
Mohammed Al-Rashidi ◽  
Hanan Al-Kindi ◽  
...  
Keyword(s):  
Rapid Test ◽  
Diagnostic Algorithm ◽  
High Specificity ◽  
Significant Negative Correlation ◽  
Test Accuracy ◽  
Reverse Transcription Pcr ◽  
Negative Results ◽  
Significant Burden ◽  
Antigen Tests ◽  
Low Sensitivity

Objectives: Considering the increasing, significant burden that coronavirus disease 2019 (COVID-19) imposes on the healthcare system, the need for simple, rapid, and affordable diagnostic tests to support the existing costly and demanding polymerase chain reaction (PCR) assay becomes required. This prospective diagnostic test accuracy study aims to evaluate the performance of four different COVID-19 rapid antigen tests compared to real-time reverse transcription PCR (rRT-PCR) between June and July 2020 to determine the feasibility of integrating these tests into the diagnostic algorithm in clinical settings. Methods: Swabs were collected from 306 patients and analyzed using rRT-PCR and antigen tests from four different providers. Results: The antigen tests’ sensitivities were 65.8%, 69.8%, 64.0%, and 64.3% for the STANDARD™ Q COVID-19 Ag test, PCL COVID-19 Ag Rapid fluorescent immunoassay (FIA) test, BIOCREDIT COVID-19 Ag test, and Sofia SARS-CoV-2 antigen FIA test, respectively. Specificity was 94.1% for PCL COVID-19 Ag Rapid test and 100% for the other three assays. All assays showed a significant negative correlation between the reference rRT-PCR Ct values and Ag test results. Besides, sensitivities of the STANDARD™ Q COVID-19 Ag test, PCL COVID-19 Ag Rapid FIA test, and BIOCREDIT COVID-19 Ag test improved to ≥ 85% after exclusion of samples with PCR Ct values > 30. Conclusions: The high specificity of the rapid antigen tests and other parameters like simplicity, rapidity, and affordability suggest that antigen tests are likely to be helpful if integrated and interpreted appropriately in stepwise diagnostic algorithms. Given the low sensitivity of 64.0–69.8% of the antigen tests, we recommend that clinically relevant negative results undergo further testing Ag to confirm or exclude a COVID-19 diagnosis.

scholarly journals DIAGNOSTIC STRATEGIES FOR ENDEMIC CORONAVIRUS DISEASE 2019 (COVID-19): RAPID ANTIGEN TESTS, REPEAT TESTING, AND PREVALENCE BOUNDARIES

2021 ◽  
Author(s):  
Gerald J. Kost
Keyword(s):  
Test Performance ◽  
Point Of Care ◽  
Low Cost ◽  
Herd Immunity ◽  
Repeated Testing ◽  
Predictive Values ◽  
Diagnostic Strategies ◽  
Performance Patterns ◽  
Improved Performance ◽  
Antigen Tests

Abstract Context. – Coronavirus disease 2019 (COVID-19) rapid antigen tests generate intrinsically fast, inherently spatial, and immediately actionable results. They quickly confirm COVID-19, but weakly rule out infection. Test performance depends on prevalence and testing protocol. Both affect predictive values. Objectives. – To use original mathematics and visual logistics for interpreting COVID-19 rapid antigen test performance patterns, gauge the influence of prevalence, and evaluate repeated testing. Design. – Mathematica and open access software helped graph relationships, perform recursive computations, and compare performance patterns. PubMed retrieved articles addressing endemic COVID-19. Results. – Tiered sensitivity/specificity comprise: T1) 90%/95%; T2) 95%/97.5%; and T3) 100%/≥99%, respectively. Performance of self- and home antigen tests with Food and Drug Administration Emergency Use Authorization peaks in low prevalence. Fall-off in performance appears with increasing prevalence because suboptimal sensitivity creates false negatives. The rate of false omissions limits clinical use because of prevalence boundaries based on tolerance for risk. Mathematical analysis supports testing twice to improve predictive values and extend prevalence boundaries nearly to levels of herd immunity. Conclusions. – COVID-19 is quickly becoming endemic. Suboptimal sensitivity of rapid antigen tests limits performance in high prevalence. Risk of contagion in packed spaces (e.g., airplanes) might be avoided with dual testing 36 hours apart, allowing time for viral load to increase. Awareness of community prevalence and proof of improved performance with repeated testing will help manage COVID-19 risk, while meeting rapid decision-making needs for highly contagious and new variants (e.g., Delta). New COVID-19 variants call for high quality, low cost, readily accessible, fast, user friendly, and ubiquitous point-of-care testing.

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