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1.
J Clin Virol ; 153: 105214, 2022 Aug.
Article in English | MEDLINE | ID: covidwho-1945516

ABSTRACT

BACKGROUND: The SARS-CoV-2 pandemic has resulted in massive testing by Rapid Antigen Tests (RAT) without solid independent data regarding clinical performance being available. Thus, decision on purchase of a specific RAT may rely on manufacturer-provided data and limited peer-reviewed data. METHODS: This study consists of two parts. In the retrospective analytical part, 33 RAT from 25 manufacturers were compared to RT-PCR on 100 negative and 204 positive deep oropharyngeal cavity samples divided into four groups based on RT-PCR Cq levels. In the prospective clinical part, nearly 200 individuals positive for SARS-CoV-2 and nearly 200 individuals negative for SARS-CoV-2 by routine RT-PCR testing were retested within 72 h for each of 44 included RAT from 26 manufacturers applying RT-PCR as the reference method. RESULTS: The overall analytical sensitivity differed significantly between the 33 included RAT; from 2.5% (95% CI 0.5-4.8) to 42% (95% CI 35-49). All RAT presented analytical specificities of 100%. Likewise, the overall clinical sensitivity varied significantly between the 44 included RAT; from 2.5% (95% CI 0.5-4.8) to 94% (95% CI 91-97). All RAT presented clinical specificities between 98 and 100%. CONCLUSION: The study presents analytical as well as clinical performance data for 44 commercially available RAT compared to the same RT-PCR test. The study enables identification of individual RAT that has significantly higher sensitivity than other included RAT and may aid decision makers in selecting between the included RAT. FUNDING: The study was funded by a participant fee for each test and the Danish Regions.


Subject(s)
COVID-19 , SARS-CoV-2 , COVID-19/diagnosis , COVID-19 Testing , Clinical Laboratory Techniques/methods , Humans , Prospective Studies , Retrospective Studies , SARS-CoV-2/genetics , Sensitivity and Specificity
2.
Diagnostics (Basel) ; 12(3)2022 Mar 06.
Article in English | MEDLINE | ID: covidwho-1928499

ABSTRACT

This paper evaluates India's first officially approved self-administered rapid antigen test kit against COVID-19, a device called CoviSelf. The context is rural India. Rapid antigen tests (RATs) are currently popular in situations where vaccination rates are low, where sections of the community remain unvaccinated, where the COVID-19 pandemic continues to grow and where easy or timely access to RTPCR (reverse transcription-polymerase chain reaction) testing is not an option. Given that rural residents make up 66% of the Indian population, our evaluation focuses on the question of whether this self-administered RAT could help protect villagers and contain the Indian pandemic. CoviSelf has two components: the test and IT (information technology) parts. Using discourse analysis, a qualitative methodology, we evaluate the practicality of the kit on the basis of data in its instructional leaflet, reports about India's 'digital divide' and our published research on the constraints of daily life in Indian villages. This paper does not provide a scientific assessment of the effectiveness of CoviSelf in detecting infection. As social scientists, our contribution sits within the field of qualitative studies of medical and health problems. Self-administered RATs are cheap, quick and reasonably reliable. Hence, point-of-care testing at the doorsteps of villagers has much potential, but realising the benefits of innovative, diagnostic medical technologies requires a realistic understanding of the conditions in Indian villages and designing devices that work in rural situations. This paper forms part of a larger project regarding the COVID-19 pandemic in rural India. A follow-up study based on fieldwork is planned for 2022-2023.

3.
JMIR Form Res ; 6(6): e38113, 2022 Jun 16.
Article in English | MEDLINE | ID: covidwho-1875306

ABSTRACT

BACKGROUND: Serial testing for SARS-CoV-2 is recommended to reduce spread of the virus; however, little is known about adherence to recommended testing schedules and reporting practices to health departments. OBJECTIVE: The Self-Testing for Our Protection from COVID-19 (STOP COVID-19) study aims to examine adherence to a risk-based COVID-19 testing strategy using rapid antigen tests and reporting of test results to health departments. METHODS: STOP COVID-19 is a 12-week digital study, facilitated using a smartphone app for testing assistance and reporting. We are recruiting 20,000 participants throughout the United States. Participants are stratified into high- and low-risk groups based on history of COVID-19 infection and vaccination status. High-risk participants are instructed to perform twice-weekly testing for COVID-19 using rapid antigen tests, while low-risk participants test only in the case of symptoms or exposure to COVID-19. All participants complete COVID-19 surveillance surveys, and rapid antigen results are recorded within the smartphone app. Primary outcomes include participant adherence to a risk-based serial testing protocol and percentage of rapid tests reported to health departments. RESULTS: As of February 2022, 3496 participants have enrolled, including 1083 high-risk participants. Out of 13,730 tests completed, participants have reported 13,480 (98.18%, 95% CI 97.9%-98.4%) results to state public health departments with full personal identifying information or anonymously. Among 622 high-risk participants who finished the study period, 35.9% showed high adherence to the study testing protocol. Participants with high adherence reported a higher percentage of test results to the state health department with full identifying information than those in the moderate- or low-adherence groups (high: 71.7%, 95% CI 70.3%-73.1%; moderate: 68.3%, 95% CI 66.0%-70.5%; low: 63.1%, 59.5%-66.6%). CONCLUSIONS: Preliminary results from the STOP COVID-19 study provide important insights into rapid antigen test reporting and usage, and can thus inform the use of rapid testing interventions for COVID-19 surveillance.

4.
Dent Mater ; 38(6): e155-e159, 2022 06.
Article in English | MEDLINE | ID: covidwho-1873002

ABSTRACT

OBJECTIVE: Fast and reliable detection of infection is a key to control the SARS-CoV-2 pandemic. Lateral flow antigen tests (LFATs) are inexpensive, easy to use, but have to be verified, as they are rather unspecific and can produce both, false positive and false negative results. Our objective was to combine the speed of LFAT for SARS-CoV-2 with the reliability of qPCR tests. METHODS: A serial dilution of a patient sample positive for SARS-CoV-2 was prepared and added to LFAT wells from two manufacturers. After evaluation, the devices were opened, the strips removed and extracted in a solution. Amplification was performed using point of care PCR systems (cobas® Liat®, ID NOW™) or on a LightCycler after extraction by MagNAPure 96. RESULTS: The nucleic acid amplification systems yielded higher sensitivity to LFAT. Thus, all samples determined positive by LFAT from the serial dilution were also positive in the subsequent amplification reactions. Sensitivity using extracted eluates was 10-100 times higher. SIGNIFICANCE: The usage of LFAT is highly recommended for single samples in emergency dental or emergency clinical settings, for smaller cohorts, or even for larger population screening, as it is inexpensive and fast. Positive results can be conveniently verified directly from the test devices using either point of care test equipment or more complex laboratory equipment thus making a major impact on efficient management of infections and isolations.


Subject(s)
COVID-19 , SARS-CoV-2 , COVID-19/diagnosis , Humans , Real-Time Polymerase Chain Reaction , Reproducibility of Results , Sensitivity and Specificity
5.
Microbiol Spectr ; 10(3): e0102522, 2022 06 29.
Article in English | MEDLINE | ID: covidwho-1865143

ABSTRACT

Ensuring SARS-CoV-2 diagnostics that can reliably detect emerging variants has been an ongoing challenge. Due to the rapid spread of the Omicron variant, point-of-care (POC) antigen tests have become more widely used. This study aimed at (i) comparing the analytical sensitivity (LOD) of 4 POC antigen assays, BD Veritor, Abbott BinaxNow, Orasure InteliSwab and Quidel QuickVue, for the Omicron versus the Delta variant and (ii) verifying the reproducible detection of Omicron by the 4 antigen assays. The LOD for all four assays were evaluated using Omicron and Delta virus stocks quantified for infectivity and genome copies. The four assays detected all replicates of Omicron and Delta dilutions at 104 and 105 TCID50/mL, respectively. We quantified both viral stocks using droplet digital PCR (ddPCR), which revealed that the Omicron stock had equivalent copies of the N gene to Delta at a one log lower infectious virus. The Abbott BinaxNow and Orasure InteliSwab had the highest analytical sensitivity for Omicron while the Orasure InteliSwab and the Quidel QuickVue had the highest analytical sensitivity for Delta. When 14 SARS-CoV-2 real-time PCR positive nasal/nasopharyngeal swab samples (12 Omicron and 2 Delta, mean Ct = 19.1), were tested by the four assays, only the QuickVue detected all samples. Antigen test positivity correlated with recovery of infectious virus on cell culture in 9 out of 13 tested specimens from symptomatic, asymptomatic, unvaccinated, and vaccinated individuals. Although our study confirms the reduced analytical sensitivity of antigen testing compared to molecular methods, the Omicron variant was detectable by the four evaluated rapid antigen tests. IMPORTANCE In the manuscript, we report an evaluation of the capability of 4 point of care (POC) antigen assays, the BD Veritor, Abbott BinaxNow, Orasure InteliSwab and Quidel QuickVue to detect the Omicron variant of SARS-CoV-2, and we compared their analytical sensitivity for Omicron versus Delta. In this analysis we found that all four assays detected Omicron and Delta at 104 and 105 TCID50/mL, respectively. We further quantified the viral stocks used by droplet digital (ddPCR) and found that the Omicron stock had equivalent copies of the N gene to Delta at a one log lower infectious virus titer and that an increased RNA to infectious virus ratio may be contributing to discrepancies in limit of detection in Omicron compared to Delta. We evaluated 14 SARS-CoV-2 real-time PCR positive nasal/nasopharyngeal swab samples (12 Omicron and 2 Delta), with an average cycle threshold value of 19.1, and only the QuickVue showed 100% agreement.


Subject(s)
COVID-19 , SARS-CoV-2 , COVID-19/diagnosis , Humans , Point-of-Care Systems , SARS-CoV-2/genetics , Sensitivity and Specificity
6.
Journal of Health Sciences ; 12(1):90-97, 2022.
Article in English | Scopus | ID: covidwho-1847880

ABSTRACT

Introduction: The pandemic of Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) presented a major challenge to health-care systems around the world. To ensure the continuity of hospital care for patients with cardiovascular diseases, the clinic has formulated the strategy for prevention of transmission of SARS-CoV-2 across the hospital environment. The purpose of this paper is to present the strategy for the prevention of transmission of SARS-CoV-2 in a healthcare facility, using Antigen Rapid Diagnostic Tests (Ag-RDTs). Methods: A description of the work from the hospital committee for the prevention and control of the SARS-CoV-2 epidemic is presented. The hospital has adopted the zero-case strategy. Each positive Ag-RDTs test was sent for confirmation by real-time Reverse Transcription Polymerase Chain Reaction (RT-PCR). Results: During the observed period, 6569 tests were performed at the Magdalena Clinic. Of these, a total of 6100 Ag-RDTs were performed, while 469 were recorded by RT-PCR test. Of these tests, a total of 181 tests showed a positive result, which is a share of 2.75% of all tests performed, of which 144 (2.19%) positive findings were detected among staff. In Ag-RDTs alone, a total of 86 positive people were detected, which is 1.41% of those tested on this type of test. Conclusion: The use of antigen rapid diagnostic tests is an effective and reliable method for the early detection of asymptomatic individuals infected with SARS-CoV-2 in a hospital setting. This strategy can significantly contribute to the insurance of uninterrupted healthcare, providing regular workflow processes, and the care of patients in the safest possible way. © 2022. Babić, et al.;. All Rights Reserved.

7.
Emerg Microbes Infect ; 11(1): 1394-1401, 2022 Dec.
Article in English | MEDLINE | ID: covidwho-1830896

ABSTRACT

The fast-spreading Omicron variant of SARS-CoV-2 overwhelmed Hong Kong, causing the fifth wave of COVID-19. It remains to be determined what mitigation measures might have played a role in reversing the rising trend of confirmed cases in this major outbreak. The government of Hong Kong has launched the mass rapid antigen tests (RAT) in the population and the StayHomeSafe scheme since February 2022. In this study, we examined the impact of the mass RAT on disease transmission and the case fatality ratio. It was suggested that the implementation of RAT plausibly played a role in the steady decrease of the effective reproduction number, leading to diminished SARS-CoV-2 transmission. In addition, we projected the disease burden of the outbreak in a scenario analysis to highlight the necessity of the StayHomeSafe scheme in Hong Kong. The Omicron outbreak experience in Hong Kong may provide actionable insights for navigating the challenges of COVID-19 surges in other regions and countries.


Subject(s)
COVID-19 , SARS-CoV-2 , COVID-19/diagnosis , COVID-19/epidemiology , Disease Outbreaks , Hong Kong/epidemiology , Humans , SARS-CoV-2/genetics
8.
J Clin Virol Plus ; 2(3): 100080, 2022 Aug.
Article in English | MEDLINE | ID: covidwho-1819525

ABSTRACT

Background: SARS-CoV-2 antigen-based tests are well-calibrated to infectiousness and have a critical role to play in the COVID-19 public health response. We report the development and performance of a unique lateral flow immunoassay (LFA). Methods: Combinations of several monoclonal antibodies targeting multiple antigenic sites on the SARS-CoV-2 nucleocapsid protein (NP) were isolated, evaluated, and chosen for the development of a LFA termed CoV-SCAN (BioMedomics, Inc.). Clinical point-of-care studies in symptomatic and asymptomatic individuals were conducted to evaluate positive predictive agreement (PPA) and negative predictive agreement (NPA) with RT-PCR as comparator. Results: In laboratory testing, CoV-SCAN detected 14 recombinant N-proteins of SARS-CoV-2 variants with sensitivity in the range of 0.2-3.2 ng/mL, and 10 authentic SARS-CoV-2 variants with sensitivity in the range of 1.6-12.5 TCID50/swab. No cross reactivity was observed with other human coronaviruses or other respiratory pathogens. In clinical point-of-care testing on 148 individuals over age 2 with symptoms of ≤5 days, PPA was 87.2% (CI 95: 78.3-94.8%) and NPA was 100% (CI 95: 94.2-100%). In another 884 asymptomatic individuals, PPA was 85.7% (CI 95: 42.1-99.6%) and 99.7% (99.0-99.9%). Overall, CoV-SCAN detected over 97.2% of specimens with CT values <30 and 93.8% of nasal swab specimens with the Omicron variant, even within the first 2 days after symptom onset. Conclusions: The unique construction of CoV-SCAN using two pairs of monoclonal antibodies has resulted in a test with high performance that remains durable across multiple variants in both laboratory and clinical evaluations. CoV-SCAN should identify almost all individuals harboring infectious SARS-CoV-2. Summary: Unique construction of a point-of-care rapid antigen test using two pairs of monoclonal antibodies has led to good performance that remained durable across multiple variants in laboratory and clinical evaluations. Test should identify almost all individuals harboring infectious SARS-CoV-2.

9.
BMC Infect Dis ; 22(1): 276, 2022 Mar 22.
Article in English | MEDLINE | ID: covidwho-1759708

ABSTRACT

BACKGROUND: SARS-CoV-2 rapid antigen (Ag) detection kits are widely used in addition to quantitative reverse transcription PCR PCR (RT-qPCR), as they are cheaper with a rapid turnaround time. As there are many concerns regarding their sensitivity and specificity, in different settings, we evaluated two WHO approved rapid Ag kits in a large cohort of Sri Lankan individuals. METHODS: Paired nasopharangeal swabs were obtained from 4786 participants for validation of the SD-Biosensor rapid Ag assay and 3325 for the Abbott rapid Ag assay, in comparison to RT-qPCR. A short questionnaire was used to record symptoms at the time of testing, and blood samples were obtained from 2721 of them for detection of SARS-CoV-2 specific antibodies. RESULTS: The overall sensitivity of the SD-Biosensor Ag kit was 36.5% and the Abbott Ag test was 50.76%. The Abbott Ag test showed specificity of 99.4% and the SD-Biosensor Ag test 97.5%. At Ct values < 25, the sensitivity was 71.3% to 76.6% for the SD-Biosensor Ag test and 77.3% to 88.9% for the Abbott Ag test. The Ct values for all genes (RdRP, S, E and N) tested with all RT-qPCR kits were significantly lower for the positive results of the Abbott Ag test compared to the SD-Biosensor test. 209 (48.04%) individuals who had antibodies gave a positive RT-qPCR result, and antibody positivity rates were higher at Ct values > 30 (46.1 to 82.9%). 32.1% of those who gave a positive result with the SD-Biosensor Ag test and 26.3% of those who gave positive results with the Abbott Ag test had SARS-CoV-2 antibodies at the time of detection. CONCLUSIONS: Both rapid Ag tests appeared to be highly sensitive in detecting individuals at lower Ct values, in a community setting in Sri Lanka, but it will be important to further establish the relationship to infectivity.


Subject(s)
COVID-19 , RNA, Viral , Antibodies, Viral , COVID-19/diagnosis , Humans , RNA, Viral/genetics , SARS-CoV-2/genetics , World Health Organization
10.
Sens Actuators B Chem ; 357: 131415, 2022 Apr 15.
Article in English | MEDLINE | ID: covidwho-1720936

ABSTRACT

Facing the unstopped surges of COVID-19, an insufficient capacity of diagnostic testing jeopardizes the control of disease spread. Due to a centralized setting and a long turnaround, real-time reverse transcription polymerase chain reaction (real-time RT-PCR), the gold standard of viral detection, has fallen short in timely reflecting the epidemic status quo during an urgent outbreak. As such, a rapid screening tool is necessitated to help contain the spread of COVID-19 amid the countries where the vaccine implementations have not been widely deployed. In this work, we propose a saliva-based COVID-19 antigen test using the electrical double layer (EDL)-gated field-effect transistor-based biosensor (BioFET). The detection of SARS-CoV-2 nucleocapsid (N) protein is validated with limits of detection (LoDs) of 0.34 ng/mL (7.44 pM) and 0.14 ng/mL (2.96 pM) in 1× PBS and artificial saliva, respectively. The specificity is inspected with types of antigens, exhibiting low cross-reactivity among MERS-CoV, Influenza A virus, and Influenza B virus. This portable system is embedded with Bluetooth communication and user-friendly interfaces that are fully compatible with digital health, feasibly leading to an on-site turnaround, an effective management, and a proactive response taken by medical providers and frontline health workers.

11.
BMC Med ; 20(1): 97, 2022 02 24.
Article in English | MEDLINE | ID: covidwho-1700066

ABSTRACT

BACKGROUND: Rapid antigen diagnostic tests (Ag-RDTs) are the most widely used point-of-care tests for detecting SARS-CoV-2 infection. Since the accuracy may have altered by changes in SARS-CoV-2 epidemiology, indications for testing, sampling and testing procedures, and roll-out of COVID-19 vaccination, we evaluated the performance of three prevailing SARS-CoV-2 Ag-RDTs. METHODS: In this cross-sectional study, we consecutively enrolled individuals aged >16 years presenting for SARS-CoV-2 testing at three Dutch public health service COVID-19 test sites. In the first phase, participants underwent either BD-Veritor System (Becton Dickinson), PanBio (Abbott), or SD-Biosensor (Roche Diagnostics) testing with routine sampling procedures. In a subsequent phase, participants underwent SD-Biosensor testing with a less invasive sampling method (combined oropharyngeal-nasal [OP-N] swab). Diagnostic accuracies were assessed against molecular testing. RESULTS: Six thousand nine hundred fifty-five of 7005 participants (99%) with results from both an Ag-RDT and a molecular reference test were analysed. SARS-CoV-2 prevalence and overall sensitivities were 13% (188/1441) and 69% (129/188, 95% CI 62-75) for BD-Veritor, 8% (173/2056) and 69% (119/173, 61-76) for PanBio, and 12% (215/1769) and 74% (160/215, 68-80) for SD-Biosensor with routine sampling and 10% (164/1689) and 75% (123/164, 68-81) for SD-Biosensor with OP-N sampling. In those symptomatic or asymptomatic at sampling, sensitivities were 72-83% and 54-56%, respectively. Above a viral load cut-off (≥5.2 log10 SARS-CoV-2 E-gene copies/mL), sensitivities were 86% (125/146, 79-91) for BD-Veritor, 89% (108/121, 82-94) for PanBio, and 88% (160/182, 82-92) for SD-Biosensor with routine sampling and 84% (118/141, 77-89) with OP-N sampling. Specificities were >99% for all tests in most analyses. Sixty-one per cent of false-negative Ag-RDT participants returned for testing within 14 days (median: 3 days, interquartile range 3) of whom 90% tested positive. CONCLUSIONS: Overall sensitivities of three SARS-CoV-2 Ag-RDTs were 69-75%, increasing to ≥86% above a viral load cut-off. The decreased sensitivity among asymptomatic participants and high positivity rate during follow-up in false-negative Ag-RDT participants emphasise the need for education of the public about the importance of re-testing after an initial negative Ag-RDT should symptoms develop. For SD-Biosensor, the diagnostic accuracy with OP-N and deep nasopharyngeal sampling was similar; adopting the more convenient sampling method might reduce the threshold for professional testing.


Subject(s)
COVID-19 , Adolescent , Antigens, Viral/analysis , COVID-19 Testing , COVID-19 Vaccines , Cross-Sectional Studies , Humans , SARS-CoV-2 , Sensitivity and Specificity
12.
J Clin Virol ; 147: 105080, 2022 02.
Article in English | MEDLINE | ID: covidwho-1693299

ABSTRACT

BACKGROUND: Viral diversity presents an ongoing challenge for diagnostic tests, which need to accurately detect all circulating variants. The Abbott Global Surveillance program monitors severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) variants and their impact on diagnostic test performance. OBJECTIVES: To evaluate the capacity of Abbott molecular, antigen, and serologic assays to detect circulating SARS-CoV-2 variants, including all current variants of concern (VOC): B.1.1.7 (alpha), B.1.351 (beta), P.1 (gamma) and B.1.617.2 (delta). STUDY DESIGN: Dilutions of variant virus cultures (B.1.1.7, B.1.351, B.1.429, B.1.526.1, B.1.526.2, B.1.617.1, B.1.617.2, P.1, R.1 and control isolate WA1) and a panel of N = 248 clinical samples from patients with sequence confirmed variant infections (B.1.1.7, B.1.351, B.1.427, B.1.429, B.1.526, B.1.526.1, B.1.526.2, P.1, P.2, R.1) were evaluated on at least one assay: Abbott ID NOW COVID-19, m2000 RealTime SARS-CoV-2, Alinity m SARS-CoV-2, and Alinity m Resp-4-Plex molecular assays; the BinaxNOW COVID-19 Ag Card and Panbio COVID-19 Ag Rapid Test Device; and the ARCHITECT/Alinity i SARS-CoV-2 IgG and AdviseDx IgM assays, Panbio COVID-19 IgG assay, and ARCHITECT/Alinity i AdviseDx SARS-CoV-2 IgG II assay. RESULTS: Consistent with in silico predictions, each molecular and antigen assay detected VOC virus cultures with equivalent sensitivity to the WA1 control strain. Notably, 100% of all tested variant patient specimens were detected by molecular assays (N = 197 m2000, N = 88 Alinity m, N = 99 ID NOW), and lateral flow assays had a sensitivity of >94% for specimens with genome equivalents (GE) per device above 4 log (85/88, Panbio; 54/57 Binax). Furthermore, Abbott antibody assays detected IgG and IgM in 94-100% of sera from immune competent B.1.1.7 patients 15-26 days after symptom onset. CONCLUSIONS: These data confirm variant detection for 11 SARS-CoV-2 assays, which is consistent with each assay target region being highly conserved. Importantly, alpha, beta, gamma, and delta VOCs were detected by molecular and antigen assays, indicating that these tests may be suitable for widescale use where VOCs predominate.


Subject(s)
COVID-19 , SARS-CoV-2 , Antibodies, Viral , Humans , Sensitivity and Specificity , Serologic Tests
13.
J Sch Health ; 92(5): 445-451, 2022 05.
Article in English | MEDLINE | ID: covidwho-1685374

ABSTRACT

BACKGROUND: School-based COVID-19 testing is a potential strategy to limit COVID-19 transmission among youth in congregate settings such as schools, sports programs, and summer camps. The purpose of this study is to evaluate the feasibility and effectiveness of frequent rapid antigen testing at a supervised distance-learning setting for elementary and middle school children while their schools were closed. METHODS: This evaluation examines participation rates and testing data in addition to qualitative analysis of focus groups from a Los Angeles City-sponsored rapid antigen testing pilot program. In total, 434 children and staff were enrolled in the 13-week pilot program in the spring of 2021. RESULTS: In this pilot program, 2482 rapid antigen tests were administered, resulting in 3 positive test results, 1 of which was a false positive (confirmed by polymerase chain reaction testing) and 0 outbreaks or community spread. CONCLUSIONS: Throughout this pilot program, implementing rapid antigen tests allowed for the quick identification and isolation of potentially COVID-19-positive children, improved perceived safety for parents and staff who interact with children, and demonstrated the ability for staff and non-health care professionals in a school-based setting to implement a widespread COVID-19 screening program with minimal training.


Subject(s)
COVID-19 , Education, Distance , Adolescent , COVID-19/diagnosis , COVID-19/epidemiology , COVID-19 Testing , Child , Humans , SARS-CoV-2 , Students
14.
J Public Health (Oxf) ; 2022 Feb 04.
Article in English | MEDLINE | ID: covidwho-1684779

ABSTRACT

BACKGROUND: Twice weekly lateral flow tests (LFTs) for secondary school children was UK Government policy from 8 March 2021. We evaluate use of LFTs (both supervised at test centres, and home test kits) in school-aged children in Cheshire and Merseyside. METHODS: We report (i) number of LFT positives (ii) proportion of LFT positive with confirmatory reverse transcription polymerase chain reaction (PCR) test within 2 days, and (iii) agreement between LFT-positive and confirmatory PCR, and dependence of (i-iii) on COVID-19 prevalence. FINDINGS: 1 248 468 LFTs were taken by 211 255 12-18 years old, and 163 914 by 52 116 5-11 years old between 6 November 2020 and 31 July 2021. Five thousand three hundred and fourteen (2.5%) 12-18 years old and 1996 (3.8%) 5-11 years old returned LFT positives, with 3829 (72.1%) and 1535 (76.9%) confirmatory PCRs, and 3357 (87.7%) and 1383 (90.1%) confirmatory PCR-positives, respectively.Monthly proportions of LFT positive with PCR negative varied between 4.7% and 35.3% in 12-18 years old (corresponding proportion of all tests positive: 9.7% and 0.3%).Deprivation and non-White ethnicity were associated with reduced uptake of confirmatory PCR. INTERPRETATION: Substantial inequalities in confirmatory testing need more attention to avoid further disadvantage through education loss. When prevalence is low additional measures, including confirmatory testing, are needed. Local Directors of Public Health taking more control over schools testing may be needed. FUNDING: DHSC, MRC, NIHR, EPSRC.

15.
J Med Virol ; 93(12): 6512-6518, 2021 12.
Article in English | MEDLINE | ID: covidwho-1544296

ABSTRACT

There is a great demand for more rapid tests for SARS-CoV-2 detection to reduce waiting time, boost public health strategies for combating disease, decrease costs, and prevent overwhelming laboratory capacities. This study was conducted to assess the performance of 10 lateral flow device viral antigen immunoassays for the detection of SARS-CoV-2 in nasopharyngeal swab specimens. We analyzed 231 nasopharyngeal samples collected from October 2020 to December 2020, from suspected COVID-19 cases and contacts of positive cases at Biotechnology Research Center laboratories, Tripoli, Libya. The performance of 10 COVID-19 Antigen (Ag) rapid test devices for the detection of SARS-CoV-2 antigen was compared to a quantitative reverse transcription-polymerase chain reaction (RT-qPCR). In this study, 161 cases had symptoms consistent with COVID-19. The mean duration from symptom onset was 6.6 ± 4.3 days. The median cycle threshold (Ct ) of positive samples was 25. Among the 108 positive samples detected by RT-qPCR, the COVID-19 antigen (Ag) tests detected 83 cases correctly. All rapid Ag test devices used in this study showed 100% specificity. While tests from six manufacturers had an overall sensitivity range from 75% to 100%, the remaining four tests had a sensitivity of 50%-71.43%. Sensitivity during the first 6 days of symptoms and in samples with high viral loads (Ct < 25), was 100% in all but two of the test platforms. False-negative samples had a median Ct of 34 and an average duration of onset of symptoms of 11.3 days (range = 5-20 days). Antigen test diagnosis has high sensitivity and specificity in early disease when patients present less than 7 days of symptom onset. Patients are encouraged to test as soon as they get COVID-19-related symptoms within 1 week and to seek medical advice within 24 h if they develop disturbed smell/taste. The use of rapid antigen tests is important for controlling the COVID-19 pandemic and reducing the burden on molecular diagnostic laboratories.


Subject(s)
Antigens, Viral/analysis , COVID-19 Serological Testing/methods , COVID-19/diagnosis , Immunoassay/methods , Adult , COVID-19 Serological Testing/economics , False Negative Reactions , Female , Humans , Immunoassay/economics , Male , Nasopharynx/virology , Prospective Studies , SARS-CoV-2/immunology , Sensitivity and Specificity , Time Factors , Viral Load
16.
Eur J Clin Microbiol Infect Dis ; 41(2): 305-312, 2022 Feb.
Article in English | MEDLINE | ID: covidwho-1520373

ABSTRACT

The reverse transcriptase polymerase chain reaction (RT-PCR) continues to be the reference diagnostic method for the confirmation of COVID-19 cases; however, rapid antigen detection tests (RADT) have recently been developed. The purpose of the study is to assess the performance of rapid antigen-based COVID-19 testing in the context of hospital outbreaks. This was an observational, cross-sectional study. The study period was from October 2020 to January 2021. The "Panbio COVID-19 AG" RADT (Abbott) was performed and TaqPath COVID-19 test RT-PCR. The samples were obtained from hospitalised patients in suspected outbreak situations at the Ramón y Cajal Hospital. A hospital outbreak was defined as the presence of 3 or more epidemiologically linked cases. The sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) of the RADT were calculated using RT-PCR as a reference. A total of 17 hospital outbreaks were detected in 11 hospital units during the study period, in which 34 RT-PCR and RADT screenings were performed. We obtained 541 samples, which were analysed with RT-PCR and a further 541 analysed with RADT. Six RADT tests gave conflicting results with the RT-PCR, 5 of them with a negative RADT and positive RT-PCR and one with positive RADT and a negative RT-PCR. The sensitivity of the RADT was 83.3% (65.3-94.4%) and the specificity was 99.8% (98.9-100%). The PPV was 96.2% (80.4-99.9%) and the NPV was 99% (97.7-99.7%). The RADT shows good diagnostic performance in patients on non-COVID-19 hospital wards, in the context of an outbreak.


Subject(s)
Antigens, Viral/immunology , COVID-19 Serological Testing/methods , Diagnostic Tests, Routine/methods , Pandemics , Cross-Sectional Studies , Humans , Sensitivity and Specificity , Spain/epidemiology
17.
Viruses ; 13(10)2021 10 06.
Article in English | MEDLINE | ID: covidwho-1463834

ABSTRACT

The search for effective methods to detect patients who excrete a viable virus is one of the urgent tasks of modern biomedicine. In the present study, we examined the diagnostic value of two antigen tests, BIOCREDIT COVID-19 Ag (RapiGEN Inc., Anyang, Korea) and SGTI-flex COVID-19 Ag (Sugentech Inc., Cheongju, Korea), for their diagnostic value in identifying patients who excrete viable SARS-CoV-2. As part of the study, we examined samples from 106 patients who had just been admitted to the hospital and who had undergone quantitative RT-PCR and assessment of viability of SARS-CoV-2 using cell culture. Assessment of the tests' value for detecting samples containing viable virus showed high sensitivity for both tests. Sensitivity was 78.6% (95% CI, from 49.2% to 95.3%) for SGTI-flex COVID-19 Ag and 100% (95% CI, from 76.8% to 100%) for Biocredit COVID-19 Ag. The specificity of rapid tests was significantly higher than that of RT-PCR and was 66.3% (95% CI, from 55.7% to 75.8%) and 67.4% (95% CI, from 56.8% to 76.8%) for SGTI-flex COVID-19 Ag and Biocredit COVID-19 Ag versus 30.4% (95% CI, from 21.3% to 40.9%) obtained for PCR. Thus, for tasks of identifying viable SARS-CoV-2 during screening of conditionally healthy people, as well as monitoring those quarantined, rapid tests show significantly better results.


Subject(s)
Antigens, Viral/analysis , Antigens, Viral/immunology , COVID-19 Serological Testing/methods , COVID-19/diagnosis , SARS-CoV-2/immunology , Adult , Aged , Aged, 80 and over , COVID-19 Nucleic Acid Testing , Female , Humans , Male , Mass Screening/methods , Middle Aged , Moscow , Point-of-Care Testing , Polymerase Chain Reaction , Sensitivity and Specificity
18.
Wien Med Wochenschr ; 172(3-4): 70-73, 2022 Mar.
Article in English | MEDLINE | ID: covidwho-1439730

ABSTRACT

BACKGROUND: Over the past year, there has been a significant increase in rapid antigen test (RAT) detection of SARS-CoV­2 COVID-19. Antigen detection is usually inferior to real-time reverse transcription polymerase chain reaction (RT-PCR) in terms of sensitivity and specificity. The aim of this study was to evaluate a RAT for specificity and sensitivity in an asymptomatic collective. METHODS: The study was carried out in January 2021 at a hospital located in a district with a 7-day index and an average of more than 100 cases per 100,000 inhabitants. COVID-19 patients are treated at this hospital. All employees with symptoms typical of COVID-19 were not allowed to go to work. We used RAT by Roche® (Roche Diagnostics GmbH, D-68305 Mannheim) and RT-PCR on our employees. The testing was done voluntarily. We performed RT-PCR and RAT using two swab tubes at the same time. RESULTS: We could correlate 919 RAT to 919 RT-PCR tests. 12 people tested positive in RAT. All 12 tests were validated by RT-PCR. There was not one incorrect positive result in RAT. In one person COVID-19 was not detected by RAT, but then positively identified with a RT-PCR. In the group of positive RAT, the mean cycle threshold (CT) value was 19.95. Our results showed a sensitivity of 92.3%, CI (confidence interval) [0.78; 1.00] and a specificity of 100.00% CI [1.0; 1.0]. CONCLUSION: RAT can be an important tool for screening for SARS-CoV­2 COVID-19 at the point of care. With low cost and resource needs, high specificity, and high specificity, RAT are performed best during the early stages of SARS-CoV­2 COVID-19, when the viral loads are high.


Subject(s)
COVID-19 , COVID-19/diagnosis , Humans , Mass Screening/methods , Prospective Studies , SARS-CoV-2 , Sensitivity and Specificity
19.
J Clin Microbiol ; 59(10): e0110721, 2021 09 20.
Article in English | MEDLINE | ID: covidwho-1430157

ABSTRACT

The reported sensitivity of rapid, antigen-based diagnostics for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection varies. Few studies have evaluated rapid antigen tests in real-world settings or among large populations. Beginning October 2020, Florida offered individuals presenting for SARS-CoV-2 testing PCR testing if they tested positive by the Abbott BinaxNOW COVID-19 antigen (Ag) card, were symptomatic, or required or requested PCR testing. We compared results among individuals who received both types of tests at four publicly accessible testing sites across Florida. We calculated the positive percent agreement (PPA) between the two test types by symptom status. Subsequently, we evaluated the PPA among individuals regardless of symptoms with lower cycle threshold values (<30). Overall, 18,457 individuals were tested via both methods, of which 3,153 (17.1%) were positive by PCR. The PPA for the Abbott BinaxNOW COVID-19 Ag card using the PCR comparator was 49.2% (95% confidence interval [CI], 47.4% to 50.9%). Among symptomatic individuals the PPA was 51.9% (95% CI, 49.7% to 54.0%). When restricted to positive PCR tests with a cycle threshold value of <30, regardless of symptom status, the PPA was 75.3% (95% CI, 72.8% to 77.6%). The PPA of the Abbott BinaxNOW COVID-19 Ag card compared with PCR was lower than that previously reported. Our findings may reflect the performance of the BinaxNOW antigen test in real-world settings.


Subject(s)
COVID-19 , SARS-CoV-2 , Antigens, Viral , COVID-19 Testing , Florida , Humans , Polymerase Chain Reaction , Sensitivity and Specificity
20.
Microorganisms ; 9(9)2021 Sep 16.
Article in English | MEDLINE | ID: covidwho-1410330

ABSTRACT

Rapid antigen tests (RATs) are an integral part of SARS-CoV-2 containment strategies. As emerging variants of concern (VOCs) displace the initially circulating strains, it is crucial that RATs do not fail to detect these new variants. In this study, four RATs for nasal swab testing were investigated using cultured strains of B.1.1 (non-VOC), B.1.1.7 (Alpha), B.1.351 (Beta), P.1 (Gamma), and B.1.617.2 (Delta). Based on dilution series in cell culture medium and pooled saliva, the limit of detection of these RATs was determined in a laboratory setting. Further investigations on cross-reactivity were conducted using recombinant N-protein from seasonal human coronaviruses (hCoVs). RATs evaluated showed an overall comparable performance with cultured strains of the non-VOC B.1.1 and the VOCs Alpha, Beta, Gamma, and Delta. No cross-reactivity was detected with recombinant N-protein of the hCoV strains HKU1, OC43, NL63, and 229E. A continuous evaluation of SARS-CoV-2 RAT performance is required, especially with regard to evolving mutations. Moreover, cross-reactivity and interference with pathogens and other substances on the test performance of RATs should be consistently investigated to ensure suitability in the context of SARS-CoV-2 containment.

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