scholarly journals Field performance of NowCheck Rapid antigen test for SARS-CoV-2 in Kisumu County, western Kenya

2021 ◽  
Author(s):  
Simon N Onsongo ◽  
Kephas Otieno ◽  
Shannen van Duijn ◽  
Hellen Barsosio ◽  
Emily R Adams ◽  
...  
Keyword(s):  
Low Cost ◽  
Field Performance ◽  
Field Evaluation ◽  
Turnaround Time ◽  
Rt Pcr ◽  
High Demand ◽  
Western Kenya ◽  
Healthcare Facilities ◽  
Antigen Tests ◽  
Study Participants

Abstract Background Low- and middle-income countries (LMICs) are increasingly adopting low-cost Coronavirus disease 2019 (COVID-19) rapid antigen tests to meet the high demand for SARS-CoV-2 testing. Whilst testing using real-time polymerase chain reaction (RT-PCR) is the current gold standard, its widespread use in LMICs is limited by high costs, turnaround times and is not readily available in most places. COVID-19 antigen tests (Ag-RDT) provide a suitable alternative due to their low cost, rapid turnaround time and easy to set up and use. This study aimed to assess the field performance of the NowCheck COVID-19 antigen kit (Ag-RDT) as a point of care test (POCT) in select healthcare facilities in western Kenya. Methods We conducted a prospective multi-facility field evaluation study of the NowCheck COVID-19 rapid antigen test (Ag-RDT) compared to SARS-CoV-2 RT-PCR (RT-PCR). After obtaining informed consent, trained laboratory technicians collected two pairs of oropharyngeal and nasopharyngeal swabs, both antigen and RT-PCR testing, first for Ag-RDT and next for RT-PCR. We performed Ag-RDTs on-site and shared the results with both the study participants and their healthcare providers within 15-30 minutes. We carried out all RT-PCR tests in a central referral laboratory. The turnaround time for RT-PCR results was typically 24-48 hours. We captured the results of both methods using an electronic digital application. Findings Between December 2020 and March 2021, we enrolled 997 participants who met the Kenyan Ministry of Health COVID-19 case definition. The median age of study participants was 39 years (range one to 80 years), with 54% male. Ag-RDT had a sensitivity of 84.5% (76.0-90.8) and a specificity of 94.4% (95% CI: 92.7-95.8) with an accuracy of 94.2% (92.5- 95.6) when a cycle threshold value (Ct value) of ≤35 was used. The highest sensitivity of 87.7% (77.2-94.5) was observed in samples with Ct values ≤ 30 and the highest specificity of 97.5% (96.2-98.5) at Ct value of <40. Interpretation The NowCheck COVID-19 Ag-RDT showed good performance in field evaluation in multiple healthcare facilities in a developing country. The sensitivity of the kit exceeded the minimum recommended cut-off of 80% as recommended by WHO1. The high specificity of this kit at 94.4% at Ct values ≤33 and 97.5% at Ct values <40 matched that of real-time PCR, making it a good rule-out test for symptomatic patients with COVID-19- like symptoms. The faster turnaround time to results, lower cost, simple analytical steps requiring no equipment or infrastructure makes antigen testing an attractive field-screening method to meet the high demand for COVID-19 testing.

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 Field evaluation of COVID‐19 antigen tests versus RNA based detection: Potential lower sensitivity compensated by immediate results, technical simplicity and low cost

2021 ◽  
Author(s):  
Elaine M Matsuda ◽  
Ivana Barros Campos ◽  
Isabela Penteriche Oliveira ◽  
Daniela Rodrigues Colpas ◽  
Andreia Moreira dos Santos Carmo ◽  
...  
Keyword(s):  
Low Cost ◽  
Field Evaluation ◽  
Lower Sensitivity ◽  
Technical Simplicity ◽  
Antigen Tests

scholarly journals Diagnostic accuracy of rapid point-of-care tests for diagnosis of current SARS-CoV-2 infections in children: A systematic review and meta-analysis

2021 ◽  
Author(s):  
Naomi Fujita-Rohwerder ◽  
Lars Beckmann ◽  
Yvonne Zens ◽  
Arpana Verma
Keyword(s):  
Point Of Care ◽  
Real Life ◽  
Risk Of Bias ◽  
Diagnostic Sensitivity ◽  
Rt Pcr ◽  
Diagnostic Specificity ◽  
Life Conditions ◽  
Antigen Tests ◽  
Study Participants ◽  
Point Of Care Tests

Objective: To systematically assess the diagnostic accuracy of rapid point-of-care tests for diagnosis of current SARS-CoV-2 infections in children under real-life conditions. Study design: Multiple bibliographic databases including MEDLINE and Embase, clinical trial registries and further information sources were systematically searched for literature (last bibliographic search: May 7, 2021). Diagnostic cross-sectional or cohort studies that included paediatric study participants and evaluated rapid point-of care tests for diagnosing current SARS-CoV-2 infections against RT-PCR as the reference standard were eligible for inclusion. QUADAS-2 was used to assess the risk of bias and the applicability of the included studies. Bivariate meta-analyses with random effects were performed. Variability was assessed by subgroup analyses. Results: We included 17 studies with a total of 6355 paediatric study participants. All included studies compared antigen tests against RT-PCR. Only one study was at low risk of bias. The pooled overall diagnostic sensitivity and specificity in paediatric populations was 64.2% (95% CI: 57.4%-70.5%) and 99.1% (95% CI: 98.2%-99.5%), respectively. In symptomatic children, the pooled diagnostic sensitivity was 71.8% (95% CI: 63.6%-78.8%) and the pooled diagnostic specificity was 98.7% (95% CI: 96.6%-99.5%). The pooled diagnostic sensitivity in asymptomatic children was 56.2% (95% CI: 47.6%-64.4%) and the pooled diagnostic specificity was 98.6% (95% CI: 97.3%-99.3%). Conclusions: Performance of current antigen tests under real-life conditions varies broadly. Policymakers should especially be aware of the low diagnostic sensitivity of current antigen tests. Results should be interpreted with caution since risk of bias was predominantly judged as unclear due to poor reporting. Study Registration: CRD42021236313 (PROSPERO).

scholarly journals Accuracy and Feasibility of Point of Care (POC) Early Infant Diagnosis (EID) in Nigeria: A Field Evaluation

2021 ◽  
Vol 9 (1) ◽  
pp. 95-104
Author(s):  
Busari Olusegun
Keyword(s):  
Point Of Care ◽  
Standard Of Care ◽  
Field Evaluation ◽  
Turnaround Time ◽  
Early Infant Diagnosis ◽  
Hiv Diagnosis ◽  
Healthcare Facilities ◽  
Early Infant ◽  
Hiv Positive Mothers ◽  
First Time

The timely commencement of treatment within the first 12 weeks of life in children reduces the HIV disease progression by 75% and mortality by 76%. For all children infected with HIV to receive essential treatment and care, few things are more important than early and accurate HIV diagnosis. Traditional methods of providing Early Infant Diagnosis (EID) have been bedeviled with several challenges. Point of Care (POC) testing for EID has been recommended as a game-changer. A field evaluation was conducted across 6 healthcare facilities between February 2017 and August 2018 to determine the accuracy and operational feasibility of POC testing for EID in Nigeria. The conceptual framework rides on the WHO SDI ASSURED criteria. Participants were infants aged between 4 weeks and 18 months born to HIV-positive mothers and visiting the clinic for the first time for EID. Results obtained from the POC was compared with the Standard of Care (SOC) to determine accuracy and feasibility. A total of 245 participants took part in the study, with 76% visiting the clinic for EID within 2 months of life. The average turnaround time for EID test using the SOC was 67 days. Analysis of the 10.4% error rate indicate significant correlation by personnel (r= 0.01122, P=0.841706). An average concordance percentage of 99.6%, sensitivity of 91.7% and specificity of 100.0% was observed. Operator’s assessment indicates that the equipment is very good and acceptable. The POC testing for EID is acceptable, rapid, and robust; hence, viable for use in Nigeria.

scholarly journals Field evaluation of Rapid SARS-Cov2 Antigen screening test on self-collected deep throat saliva samples in Malaysia

2021 ◽  
Author(s):  
Noorliza Mohamad Noordin ◽  
Chee Loon Lim ◽  
Zhuo-zhi Lim ◽  
Teck Onn Lim
Keyword(s):  
Screening Program ◽  
Low Cost ◽  
False Negative ◽  
Field Evaluation ◽  
Contact Tracing ◽  
Repeated Testing ◽  
User Training ◽  
The Government ◽  
Antigen Tests ◽  
Low Sensitivity

Low cost Rapid Antigen Tests are widely used in Malaysia and the government has also mandated worksite screening as a condition for reopening. Numerous RAT kits have been approved by the Malaysian Medical Device Authority. However, it remains uncertain how these kits would perform in the field. We enrolled workers between June and September 2021 from 23 worksites. They were trained and experienced in performing RAT selftest by virtue of their worksite participation in routine screening program. These workers also had reverse transcriptase polymerase chain reaction tests in the course of mass screening or contact tracing. We also enrolled patients with PCR confirmed Covid19 from a quarantine centre. These patients were instructed on selftesting and then immediately perform RAT under supervision. Two manufacturers donated RAT for this study. A total of 340 participants were enrolled, 130 were from quarantine centre and 210 from worksites. The overall sensitivity of RAT compared to PCR was 70 percent. The specificity was 91 percent. Sensitivity decreased with increasing PCR cycle threshold values. Sensitivity is also lower among untrained subjects at each level of Ct. Logistic regression analysis confirmed false negative result is associated with Ct and participants prior training and experience. This study shows that in the real world, RAT performance were markedly lower than that reported by the manufacturers. The test sensitivity is dependent on the operator training and experience, as well as on viral load as measured by Ct. User training and repeated testing for screening purpose is necessary to mitigate the low sensitivity of RAT.

scholarly journals Surveillance testing for SARS-COV-2 infection in an asymptomatic athlete population: a prospective cohort study with 123 362 tests and 23 463 paired RT-PCR/antigen samples

2021 ◽  
Vol 7 (2) ◽  
pp. e001137
Author(s):  
Kimberly Harmon ◽  
Anabelle M de St Maurice ◽  
Adam C Brady ◽  
Sankar Swaminathan ◽  
Doug F Aukerman ◽  
...  
Keyword(s):  
Screening Programme ◽  
Sports Participation ◽  
High Specificity ◽  
Turnaround Time ◽  
Screening Tests ◽  
Rt Pcr ◽  
Pcr Screening ◽  
Testing Approach ◽  
Antigen Tests ◽  
Antigen Testing

ObjectiveTo assess the diagnostic accuracy of antigen compared with reverse transcriptase (RT)-PCR testing in an asymptomatic athlete screening programme and to monitor infection in college athletes.MethodsQuidel Sofia-2 SARS-CoV-2 Antigen Tests were performed daily before sports participation for football, basketball, wrestling and water polo from 29 September 2020 to 28 February 2021. Paired RT-PCR and antigen tests were performed at least once a week. Positive antigen tests were confirmed with RT-PCR.Results81 175 antigen and 42 187 RT-PCR tests were performed, including 23 462 weekly paired antigen/RT-PCR screening tests in 1931 athletes. One hundred and seventy-two athletes had a positive screening RT-PCR (0.4%), of which 83 (48%) occurred on paired testing days. The sensitivity of antigen tests varied with the frequency of RT-PCR testing and prevalence of COVID-19. The sensitivity of antigen testing was 35.7% (95% CI: 17% to 60%) and specificity 99.8% (95% CI: 99.7% to 99.9%) with once-a-week RT-PCR testing after adjusting for school prevalence. Daily antigen testing was similar to RT-PCR testing two to three times a week in identifying infection. Antigen testing identified infection before the next scheduled PCR on 89 occasions and resulted in 234 days where potentially infectious athletes were isolated before they would have been isolated with RT-PCR testing alone. Two athletic-related outbreaks occurred; 86% of total infections were community acquired.ConclusionAntigen testing has high specificity with a short turnaround time but is not as sensitive as RT-PCR. Daily antigen testing or RT-PCR testing two to three times a week is similar. There are benefits and drawbacks to each testing approach.

scholarly journals A two-pronged approach for rapid and high-throughput SARS-CoV-2 nucleic acid testing

2020 ◽  
Author(s):  
Neeru Gandotra ◽  
Irina Tikhonova ◽  
Nagarjuna R. Cheemarla ◽  
James Knight ◽  
Ellen Foxman ◽  
...  
Keyword(s):  
High Throughput ◽  
High Throughput Sequencing ◽  
Low Cost ◽  
Rna Extraction ◽  
Clinical Specimen ◽  
Rna Isolation ◽  
Turnaround Time ◽  
Ease Of Use ◽  
Diagnostic Tools ◽  
Rt Pcr

AbstractImproved molecular screening and diagnostic tools are needed to substantially increase SARS-CoV-2 testing capacity and throughput while reducing the time to receive test results. Here we developed multiplex reverse transcriptase polymerase chain reaction (m-RT-PCR) for detection of SARS-CoV-2 using rapid DNA electrophoresis and alternatively using multiplex viral sequencing (mVseq). For RNA specimens extracted from nasopharyngeal (NP) swabs in viral transport media (VTM), our assays achieved a sensitivity for SARS-CoV-2 detection corresponding to cycle threshold (Ct) of 37.2 based on testing of these specimens using quantitative reverse transcription PCR (RT-qPCR). For NP swab-VTM specimens without prior RNA extraction, sensitivity was reduced to Ct of 31.6, which was due to lower concentration of SARS-CoV-2 genome copies in VTM compared to RNA-extracted samples. Assay turnaround time was 60 minutes using rapid gel electrophoresis, 90 minutes using Agilent Bioanalyzer, and 24-48 hours using Illumina sequencing, the latter of which required a second PCR to produce a sequence-ready library using m-RT-PCR products as the template. Our assays can be employed for high-throughput sequencing-based detection of SARS-CoV-2 directly from a clinical specimen without RNA isolation, while ease-of-use and low cost of the electrophoresis-based readout enables screening, particularly in resource-constrained settings.

scholarly journals Comparative analyses of all FDA EUA-approved rapid antigen tests and RT-PCR for COVID-19 quarantine and surveillance-based isolation

2021 ◽  
Author(s):  
Chad R. Wells ◽  
Abhishek Pandey ◽  
Seyed M. Moghadas ◽  
Burton H. Singer ◽  
Gary Krieger ◽  
...  
Keyword(s):  
Relative Effectiveness ◽  
Policy Decision ◽  
Turnaround Time ◽  
Reproductive Number ◽  
Rt Pcr ◽  
Serial Testing ◽  
Test Specificity ◽  
Tool Set ◽  
Antigen Tests ◽  
Pcr Test

AbstractRapid antigen (RA) tests are being increasingly employed to detect COVID-19 infections in quarantine and surveillance. We conducted a comparative analysis of quarantine durations, testing frequencies, and false-positive rates for all of the 18 RA tests with emergency use authorization (EUA) from the FDA, and an RT-PCR test. For each test, we employed a mathematical model of imminent infections to calculate the effective reproductive number in the context of the test used for quarantine or serial testing. We informed the model with data on test specificity, temporal diagnostic sensitivity, and COVID-19 infectiousness. Our results demonstrate that the relative effectiveness of RA and RT-PCR tests in reducing post-quarantine transmission depends on the quarantine duration and the turnaround time of testing results. For quarantines shorter than five days, RA test on entry to and on exit from quarantine reduced onward transmission more than a single RT-PCR test conducted upon exit. Conducting surveillance via serial RT-PCR testing with a 24-h turnaround time, the minimum testing frequency paired with isolation of positives that is required to suppress the effective reproduction number (RE) below one was found to be every six days. RA tests reduce RE below one when conducted at a minimum frequency that ranges from every six days to every eight days. Our analysis also highlights that the risk of onward transmission during serial testing increases with the delay in obtaining the results. These RA test-specific results are an important component of the tool set for policy decision-making, and demonstrate that judicious selection of an appropriate RA test can supply a viable alternative to RT-PCR in efforts to control the spread of disease.

scholarly journals Analytical Evaluation of Visby Medical RT-PCR Portable Device for Rapid Detection of SARS-CoV-2

Diagnostics ◽  
2021 ◽  
Vol 11 (5) ◽  
pp. 813
Author(s):  
Adriana Renzoni ◽  
Francisco Perez ◽  
Marie Thérèse Ngo Nsoga ◽  
Sabine Yerly ◽  
Erik Boehm ◽  
...  
Keyword(s):  
Point Of Care ◽  
Turnaround Time ◽  
Nucleic Acid Detection ◽  
Nasopharyngeal Swab ◽  
Analytical Sensitivity ◽  
Rt Pcr ◽  
Detection Systems ◽  
Reverse Transcription Pcr ◽  
Antigen Tests ◽  
Pcr Targeting

Extended community testing constitutes one of the main strategic pillars in controlling the COVID-19 pandemic. Reverse transcription PCR (RT-PCR) targeting the SARS-CoV-2 genome on nasopharyngeal swab samples is currently the reference test. While displaying excellent analytical sensitivity and specificity, this test is costly, often requires a substantial turnaround time, and, more importantly, is subject to reagent and other material shortages. To complement this technology, rapid antigen tests have been developed and made available worldwide, allowing cheap, quick, and decentralized SARS-CoV-2 testing. The main drawback of these tests is the reduced sensitivity when RT-PCR is the gold standard. In this study, we evaluate Visby an innovative, portable, easy-to-use RT-PCR point-of-care (POC) diagnostic device. Our retrospective analysis shows that overall, compared to the Cobas 6800 RT-qPCR assay (Roche), this RT-PCR POC technology detects SARS-CoV-2 RNA with 95% sensitivity (95%CI = 86.3–99%) and 100% specificity (95% CI = 80.5–100%). For samples with cycle-threshold values below 31, we observed 100% sensitivity (95% CI = 66.4–100%). While showing an analytical sensitivity slightly below that of a standard RT-qPCR system, the evaluated Visby RT-PCR POC device may prove to be an interesting diagnostic alternative in the COVID-19 pandemic, potentially combining the practical advantages of rapid antigen tests and the robust analytical performances of nucleic acid detection systems.

scholarly journals Evaluation of Screening Tests in Bavarian Healthcare Facilities during the Second Wave of the SARS-CoV-2 Pandemic

2021 ◽  
Vol 18 (14) ◽  
pp. 7371
Author(s):  
Christina Tischer ◽  
Carolin Stupp ◽  
Patrick Janson ◽  
Kristina Willeke ◽  
Chu-Wei Hung ◽  
...  
Keyword(s):  
Screening Tests ◽  
Test Results ◽  
Rt Pcr ◽  
Term Care ◽  
Healthcare Facilities ◽  
Infection Surveillance ◽  
Antigen Tests ◽  
Asymptomatic Subjects ◽  
Second Wave

Due to the lack of data on asymptomatic SARS-CoV-2-positive persons in healthcare institutions, they represent an inestimable risk. Therefore, the aim of the current study was to evaluate the first 1,000,000 reported screening tests of asymptomatic staff, patients, residents, and visitors in hospitals and long-term care (LTC) facilities in the State of Bavaria over a period of seven months. Data were used from the online database BayCoRei (Bavarian Corona Screening Tests), established in July 2020. Descriptive analyses were performed, describing the temporal pattern of persons that tested positive for SARS-CoV-2 by real-time polymerase chain reaction (RT-PCR) or antigen tests, stratified by facility. Until 15 March 2021, this database had collected 1,038,146 test results of asymptomatic subjects in healthcare facilities (382,240 by RT-PCR, and 655,906 by antigen tests). Of the RT-PCR tests, 2.2% (n = 8380) were positive: 3.0% in LTC facilities, 2.2% in hospitals, and 1.2% in rehabilitation institutions. Of the antigen tests, 0.4% (n = 2327) were positive: 0.5% in LTC facilities, and 0.3% in both hospitals and rehabilitation institutions, respectively. In LTC facilities and hospitals, infection surveillance using RT-PCR tests, or the less expensive but less sensitive, faster antigen tests, could facilitate the long-term management of the healthcare workforce, patients, and residents.

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