Implementing SARS-CoV-2 Rapid Antigen Testing in the Emergency Ward of a Swiss University Hospital: The INCREASE Study

Following the Swiss Federal Office of Public Health (FOPH) authorization of the rapid antigen test (RAT), we implemented the use of the RAT in the emergency ward of our university hospital for patients’ cohorting. RAT triaging in association with RT-PCR allowed us to promptly isolate positive patients and save resources. Among 532 patients, overall sensitivities were 48.3% for Exdia and 41.2% for Standard Q®, PanbioTM and BD Veritor™. All RATs exhibited specificity above 99%. Sensitivity increased to 74.6%, 66.2%, 66.2% and 64.8% for Exdia, Standard Q®, PanbioTM and BD Veritor™, respectively, for viral loads above 105 copies/mL, to 100%, 97.8%, 96.6% and 95.6% for viral loads above 106 copies/mL and 100% for viral loads above 107 copies/mL. Sensitivity was significantly higher for patients with symptoms onset within four days (74.3%, 69.2%, 69.2% and 64%, respectively) versus patients with the evolution of symptoms longer than four days (36.8%, 21.1%, 21.1% and 23.7%, respectively). Among COVID-19 asymptomatic patients, sensitivity was 33%. All Immunoglobulin-A-positive patients resulted negative for RAT. The RAT might represent a useful resource in selected clinical settings as a complementary tool in RT-PCR for rapid patient triaging, but the lower sensitivity, especially in late presenters and COVID-19 asymptomatic subjects, must be taken into account.

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ImplemeNting SARS-CoV-2 Rapid antigen testing in the Emergency wArd of a Swiss univErsity hospital: the INCREASE study

10.1101/2021.02.10.21250915 ◽

2021 ◽

Author(s):

Giorgia Caruana ◽

Antony Croxatto ◽

Eleftheria Kampouri ◽

Antonios Kritikos ◽

Onya Opota ◽

...

Keyword(s):

University Hospital ◽

Lower Sensitivity ◽

Clinical Settings ◽

Rt Pcr ◽

Emergency Ward ◽

Viral Loads ◽

Molecular Tests ◽

One Step ◽

Antigen Tests ◽

Second Wave

BackgroundWhile facing a second wave in SARS-CoV-2 pandemic, in November 2020 the Swiss Federal Office of Public Health (FOPH) authorized the use of rapid antigen tests (RATs) in addition to the gold-standard reverse transcription-polymerase chain reaction (RT-PCR).MethodsWe implemented the use of RAT in the emergency ward of our university hospital for rapid patients’ triaging and compared performances of four different antigen tests. All results were compared to SARS-CoV-2 specific RT-PCR (reference standard).ResultsTriaging patients using RAT in association with RT-PCR allowed us to isolate promptly positive patients and to save resources, in a context of rapid RT-PCR reagents shortage. Among 532 patients with valid results, overall sensitivities were 48.3% for One Step Exdia and 41.2% for Standard Q®, Panbio−and BD Veritor. All four antigen tests exhibited specificity above 99%. Sensitivity increased up to 74.6%, 66.2%, 66.2% and 64.8% for One Step Exdia, Standard Q, Panbio, and BD Veritor respectively, when considering viral loads above 105copies/ml, up to 100%, 97.8%, 96.6% and 95.6% for viral loads above 106 copies/ml and 100% (for all tests) when considering viral loads above 107 copies/ml. Sensitivity was significantly higher for patients presenting with symptoms onset within 4 days (74.3%, 69.2%, 69.2% and 64%, respectively) versus patients with evolution of symptoms for more than 4 days (36.8%, 21.1%, 21.1% and 23.7%, respectively). Sensitivities of all RAT assays were of only 33% among hospitalized patients without COVID-19 symptoms.ConclusionRAT might represent a useful epidemiological resource in selected clinical settings as a complementary tool to the molecular tests for rapid patients triaging, but the lower sensitivity compared to RT-PCR, especially in late presenters and subjects without COVID-19 symptoms, must be taken into account in order to correctly use RAT for triaging.

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Comparison of SARS-CoV-2 antigen electrochemiluminescence immunoassay to RT-PCR assay for laboratory diagnosis of COVID-19 in Peshawar

Diagnosis ◽

10.1515/dx-2021-0078 ◽

2021 ◽

Vol 0 (0) ◽

Author(s):

Bilal Iqbal ◽

Maria Khan ◽

Noman Shah ◽

Mirza Muhammad Dawood ◽

Valeed Jehanzeb ◽

...

Keyword(s):

Laboratory Diagnosis ◽

Cross Sectional Study ◽

Antigen Test ◽

Rt Pcr ◽

Pcr Assay ◽

Cross Sectional ◽

Viral Loads ◽

Testing Algorithms ◽

Frequent Testing ◽

Antigen Testing

Abstract Objectives Antigen based rapid diagnostic tests possesses a potential to be utilized along with Gold standard methods to detect Covid-19 infection to cope with the demand of testing. The aim of this study was to determine diagnostic accuracy of electrochemiluminescence based automated antigen detection immunoassay comparing with molecular based test RT-PCR (Covid-19). Methods It was a cross-sectional study conducted in RMI Peshawar, from 1st April 2021 till 30th April 2021. The study comprised 170 individuals who were suspected of having Covid-19. Nasopharyngeal samples taken from suspected individuals were analyzed by RT-PCR and automated antigen test (Elecsys SARS-CoV-2 Antigen) simultaneously. The correlation of SARS-CoV-2 antigen with PCR positive and negative cases was analyzed for specificity, sensitivity respectively. Results The ECLIA based Elecsys antigen test (Roche) revealed overall sensitivity 72%, specificity 95% and accuracy of 94.9%. Sensitivity of antigen test progressively declined from 94.3% in Ct <25 to 70.8% in Ct 26–29 and then to 47.2% in Ct 30–35. Conclusions Based on the findings of our study we conclude that automated antigen testing (Elecsys SARS-CoV-2 Antigen) cannot replace molecular based testing like RT PCR. Elecsys SARS-CoV-2 Ag test should be used complementary to RT-PCR in testing algorithms. Frequent testing strategy should be adopted while using automated antigen testing to overcome its limitation in individuals with low viral loads.

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Insufficient Sensitivity of RNA Dependent RNA Polymerase Gene of SARS-CoV-2 Viral Genome as Confirmatory Test using Korean COVID-19 Cases

10.20944/preprints202002.0424.v1 ◽

2020 ◽

Cited By ~ 10

Author(s):

Soyoun Kim ◽

Dong-Min Kim ◽

Baeckseung Lee

Keyword(s):

Diagnostic Methods ◽

Confirmatory Test ◽

Test Results ◽

Rt Pcr ◽

Viral Loads ◽

Asymptomatic Patients ◽

Pcr Method ◽

Who Guideline ◽

Rna Polymerase Gene ◽

Insufficient Sensitivity

Since mid-December of 2019, coronavirus disease 2019 (COVID-19) has been spreading from Wuhan, China. As of February 21, total 75,773 confirmed cases worldwide have spread to more than two dozen countries. Transmission of COVID-19 can occur early in the course of infection since SARS-CoV-2 viral loads in asymptomatic patients are similar to that in the symptomatic patients. Therefore, more sensitive diagnostic methods are needed to detect early phase of the infection to prevent secondary or tertiary spreads. Here, we compare the RT-PCR confirmatory test results using two different SARS-CoV-2 viral RNAs from two Korean COVID-19 confirmed cases.RT-PCR method targeting the RdRP gene, which was recommended by WHO guideline, was less sensitive than targeting N genes (as per CDC guideline). Because many countries follow the WHO guideline, our findings may contribute to the early diagnosis of COVID-19.

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The Efficacy of General Practitioner Assessment of Cognition in Chinese Elders Aged 80 and Older

American Journal of Alzheimer s Disease & Other Dementias® ◽

10.1177/1533317519860333 ◽

2019 ◽

Vol 34 (7-8) ◽

pp. 523-529

Author(s):

Fang Xu ◽

Juan Juan Ma ◽

Fei Sun ◽

Jaewon Lee ◽

David W. Coon ◽

...

Keyword(s):

General Practitioner ◽

Mini Mental State Examination ◽

Mainland China ◽

University Hospital ◽

Comparable Efficacy ◽

Lower Sensitivity ◽

Clinical Settings ◽

Older Chinese ◽

State Examination ◽

Survey Questionnaires

Objectives: This study examined the efficacy of the General Practitioner Assessment of Cognition–Chinese version (GPCOG-C) in screening dementia and mild cognitive impairment (MCI) among older Chinese. Methods: Survey questionnaires were administered to 293 participants aged 80 or above from a university hospital in mainland China. Alzheimer disease and MCI were diagnosed in light of the National Institute on Aging and the Alzheimer’s Association (NIA/AA) criteria. The sensitivity and specificity of GPCOG-C and Mini-Mental State Examination (MMSE) in screening dementia and MCI were compared to the NIA/AA criteria. Results: The GPCOG-C had the sensitivity of 62.3% and specificity of 84.6% in screening MCI, which had comparable efficacy as the NIA/AA criteria. In screening dementia, GPCOG-C had a lower sensitivity (63.7%) than the MMSE and a higher specificity (82.6%) higher than the MMSE. Conclusions: The GPCOG-C is a useful and efficient tool to identify dementia and MCI in older Chinese in outpatient clinical settings.

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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

Laboratory Medicine ◽

10.1093/labmed/lmaa104 ◽

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.

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Head-to-Head Comparison of Rapid and Automated Antigen Detection Tests for the Diagnosis of SARS-CoV-2 Infection

Journal of Clinical Medicine ◽

10.3390/jcm10020265 ◽

2021 ◽

Vol 10 (2) ◽

pp. 265

Author(s):

Julien Favresse ◽

Constant Gillot ◽

Maxime Oliveira ◽

Julie Cadrobbi ◽

Marc Elsen ◽

...

Keyword(s):

Polymerase Chain Reaction ◽

Clinical Performance ◽

Antigen Detection ◽

Clinical Validation ◽

Rt Pcr ◽

Chain Reaction ◽

Viral Loads ◽

Automated Assay ◽

Polymerase Chain ◽

Asymptomatic Subjects

(1) Background: The detection of SARS-CoV-2 RNA in nasopharyngeal samples through real-time reverse transcription-polymerase chain reaction (RT-PCR) is considered the standard gold method for the diagnosis of SARS-CoV-2 infection. Antigen detection (AD) tests are more rapid, less laborious, and less expensive alternatives but still require clinical validation. (2) Methods: This study compared the clinical performance of five AD tests, including four rapid AD (RAD) tests (biotical, Panbio, Healgen, and Roche) and one automated AD test (VITROS). For that purpose, 118 (62.8%) symptomatic patients and 70 (37.2%) asymptomatic subjects were tested, and results were compared to RT-PCR. (3) Results: The performance of the RAD tests was modest and allowed us to identify RT-PCR positive patients with higher viral loads. For Ct values ≤25, the sensitivity ranged from 93.1% (95% CI: 83.3–98.1%) to 96.6% (95% CI: 88.1–99.6%), meaning that some samples with high viral loads were missed. Considering the Ct value proposed by the CDC for contagiousness (i.e., Ct values ≤33) sensitivities ranged from 76.2% (95% CI: 65.4–85.1%) to 88.8% (95% CI: 79.7–94.7%) while the specificity ranged from 96.3% (95% CI: 90.8–99.0%) to 99.1% (95% CI: 95.0–100%). The VITROS automated assay showed a 100% (95% CI: 95.5–100%) sensitivity for Ct values ≤33, and had a specificity of 100% (95% CI: 96.6–100%); (4) Conclusions: Compared to RAD tests, the VITROS assay fully aligned with RT-PCR for Ct values up to 33, which might allow a faster, easier and cheaper identification of SARS-CoV-2 contagious patients.

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The Performance of Two Rapid Antigen Tests During Population-Level Screening for SARS-CoV-2 Infection

Frontiers in Medicine ◽

10.3389/fmed.2021.797109 ◽

2021 ◽

Vol 8 ◽

Author(s):

Mohammad Alghounaim ◽

Hamad Bastaki ◽

Farah Bin Essa ◽

Hoda Motlagh ◽

Salman Al-Sabah

Keyword(s):

Positive Predictive Value ◽

Prospective Study ◽

Predictive Value ◽

Point Of Care ◽

Population Level ◽

Lower Sensitivity ◽

Rt Pcr ◽

Antigen Tests ◽

A Prospective Study ◽

Antigen Testing

Background: SARS-CoV-2 antigen assays offer a rapid mean to diagnose and isolate infected individuals. However, their utility in population-level screening is unknown.Objectives: The performance of two antigen tests in detecting SARS-CoV-2 was assessed among individuals randomly selected in the community.Study Design: A prospective study that performed head-to-head comparison of two SARS-CoV-2 antigen assays. Individuals were recruited during community SARS-CoV-2 screening over 10 working days. Demographic and clinical data were collected. Standard Q COVID-19 Ag test, a point-of-care chromatographic assay, was conducted immediately, and then the sample was transported to the virology laboratory to perform PCR and the LIAISON SARS-CoV-2 Ag chemiluminesence immunoassay.Results: respiratory samples from 991 individuals were collected, and 62 were positive by PCR. Inconclusive PCR results were observed in 19 samples and were excluded. The median age of participants was 40.2 years (IQR 32.3–47.8), and 932 (94%) were males. Most (77.4%) of infections were asymptomatic. The sensitivity and the specificity of the LIAISON assay were 43.3% (95%CI 30.6–56.8) and 99.9% (95%CI 99.3–100). The Standard Q assay had lower sensitivity (30.6%, 95%CI 19.6–43.7) but similar specificity (98.8%, 95%CI, 97.8–99.4). Similarly, the LIAISON assay had higher positive predictive value (96.3%, 95%CI 81–99.9% vs. 63.3%, 95%CI, 43.9–80.1%). Both assays performed better in symptomatic patients and among samples with a low-cycle threshold (Ct < 25).Conclusion: In our setting of random community surveillance, rapid antigen testing of nasopharyngeal swabs by either LIAISON SARS-CoV-2 Ag (DiaSorin) or Standard Q COVID-19 Ag (SD Biosensor) was less sensitive to detecting SARS-CoV-2 than the TaqPath COVID-19 RT-PCR.

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Evaluation of the SARS-CoV-2 positivity ratio and upper respiratory tract viral load among asymptomatic individuals screened before hospitalization or surgery in Flanders, Belgium

PLoS ONE ◽

10.1371/journal.pone.0259908 ◽

2021 ◽

Vol 16 (11) ◽

pp. e0259908

Author(s):

Laura Heireman ◽

Steven Abrams ◽

Peggy Bruynseels ◽

Reinoud Cartuyvels ◽

Lize Cuypers ◽

...

Keyword(s):

Viral Load ◽

Respiratory Tract ◽

Age Group ◽

Test Results ◽

Rt Pcr ◽

Median Viral Load ◽

Viral Loads ◽

Asymptomatic Patients ◽

Positivity Ratio ◽

Second Wave

Introduction The incidence of Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) infections in the Belgian community is mainly estimated based on test results of patients with coronavirus disease (COVID-19)-like symptoms. The aim of this study was to investigate the evolution of the SARS-CoV-2 reverse transcriptase polymerase chain reaction (RT-PCR) positivity ratio and distribution of viral loads within a cohort of asymptomatic patients screened prior hospitalization or surgery, stratified by age category. Materials/Methods We retrospectively studied data on SARS-CoV-2 real-time RT-PCR detection in respiratory tract samples of asymptomatic patients screened pre-hospitalization or pre-surgery in nine Belgian hospitals located in Flanders over a 12-month period (1 April 2020–31 March 2021). Results In total, 255925 SARS-CoV-2 RT-PCR test results and 2421 positive results for which a viral load was reported, were included in this study. An unweighted overall SARS-CoV-2 real-time RT-PCR positivity ratio of 1.27% was observed with strong spatiotemporal differences. SARS-CoV-2 circulated predominantly in 80+ year old individuals across all time periods except between the first and second COVID-19 wave and in 20–30 year old individuals before the second COVID-19 wave. In contrast to the first wave, a significantly higher positivity ratio was observed for the 20–40 age group in addition to the 80+ age group compared to the other age groups during the second wave. The median viral load follows a similar temporal evolution as the positivity rate with an increase ahead of the second wave and highest viral loads observed for 80+ year old individuals. Conclusion There was a high SARS-CoV-2 circulation among asymptomatic patients with a predominance and highest viral loads observed in the elderly. Moreover, ahead of the second COVID-19 wave an increase in median viral load was noted with the highest overall positivity ratio observed in 20–30 year old individuals, indicating they could have been the hidden drivers of this wave.

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Is the glass half full? Extraction-free RT-LAMP to detect SARS-CoV-2 is less sensitive but highly specific compared to standard RT-PCR in 101 samples

10.1101/2020.12.07.20239558 ◽

2020 ◽

Author(s):

John J. Schellenberg ◽

Margaret Ormond ◽

Yoav Keynan

Keyword(s):

Point Of Care ◽

N Gene ◽

Nasopharyngeal Swab ◽

Lower Sensitivity ◽

Rt Pcr ◽

Public And Private ◽

Viral Loads ◽

Negative Results ◽

Viral Transport Medium ◽

Point Of Care Tests

AbstractThe current scale of public and private testing cannot be expected to meet the emerging need for higher levels of community-level and repeated screening of asymptomatic Canadians for SARS-CoV-2. Rapid point-of-care techniques are increasingly being deployed to fill the gap in screening levels required to identify undiagnosed individuals with high viral loads. However, rapid, point-of-care tests often have lower sensitivity in practice. Reverse transcription loop-mediated isothermal amplification (RT-LAMP) for SARS-CoV-2 has proven sensitive and specific and provides visual results in minutes. Using a commercially available kit for RT-LAMP and primer set targetting nucleocapsid (N) gene, we tested a blinded set of 101 archived nasopharyngeal (NP) swab samples with known RT-PCR results. RT-LAMP reactions were incubated at 65°C for 30 minutes, using heat-inactivated nasopharyngeal swab sample in viral transport medium, diluted tenfold in water, as input. RT-LAMP agreed with all RT-PCR defined negatives (N=51), and all positives with Ct less than 20 (N=24), 65% of positives with Ct between 20-30 (N=17), and no positives with Ct greater than 30 (N=9). RT-LAMP requires fewer and different core components, so may not compete directly with the mainline testing workflow, preserving precious central laboratory resources and gold standard tests for those with the greatest need. Careful messaging must be provided when using less-sensitive tests, so that people are not falsely reassured by negative results – “glass half empty” – in exchange for reliable detection of those with high levels of virus within an hour, using <$10 worth of chemicals – “glass half full”.

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513. Viral kinetics of SARS-CoV-2 in patients with COVID-19

Open Forum Infectious Diseases ◽

10.1093/ofid/ofaa439.707 ◽

2020 ◽

Vol 7 (Supplement_1) ◽

pp. S322-S323

Author(s):

Da Young Kim ◽

Ju-Hyung Lee ◽

Hyeon Jeong Oh ◽

Jun-won Seo ◽

Na Ra Yun ◽

...

Keyword(s):

Chest Radiograph ◽

Symptom Onset ◽

Supplemental Oxygen ◽

University Hospital ◽

Upper Respiratory Tract ◽

Rt Pcr ◽

Viral Kinetics ◽

Viral Loads ◽

Severe Group ◽

Kinetics Of

Abstract Background As only few studies have analyzed viral kinetics between the incubation and symptomatic periods of COVID-19 patients, we investigated the viral kinetics and compared viral loads between patients with mild and severe COVID-19. Methods We determined the viral kinetics of 10 patients diagnosed with COVID-19 at Chosun University Hospital. Six patients were classified into the “mild” group and 4 into the “severe” group according to supplemental oxygen use during admission. Samples were collected via nasopharyngeal swabs and sputum specimens. SARS-CoV-2 was detected using real-time reverse transcription-polymerase chain reaction (RT-PCR). Chest radiograph scores during hospitalization were obtained Results Ct values of the upper respiratory tract specimens were low during the early stages after symptom onset but gradually increased over time in both groups. The severe group had lower Ct values than the mild group. The Ct values of the RdRP and E genes on day 6 after symptom onset were significantly lower in the severe group than in the mild group (p < 0.05). Three of 6 patients had positive results on RT-PCR even before symptom onset; 2 of them had the lowest Ct values. The chest radiograph scores were higher in the severe group than in the mild group, and the score in the severe group was the highest at approximately 3 weeks after symptom onset. Ct values when the RdRP gene and E gene were targeted to detect SARS-CoV-2 on the basis of the days after symptom onset in all the patients Conclusion Viral load and chest radiograph scores were significantly different between the severe and mild groups of COVID-19 patients. Disclosures All Authors: No reported disclosures

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