Graphene-Based Electrochemical Nano-Biosensors for Detection of SARS-CoV-2

COVID-19, a viral respiratory illness, is caused by Severe Acute Respiratory Syndrome Corona Virus 2 (SARS-CoV-2), which was first identified in Wuhan, China, in 2019 and rapidly spread worldwide. Testing and isolation were essential to control the virus's transmission due to the severity of the disease. In this context, there is a global interest in the feasibility of employing nano-biosensors, especially those using graphene as a key material, for the real-time detection of the virus. The exceptional properties of graphene and the outstanding performance of nano-biosensors in identifying various viruses prompted a feasibility check on this technology. This paper focuses on the recent advances in using graphene-based electrochemical biosensors for sensing the SARS-CoV-2 virus. Specifically, it reviews various types of electrochemical biosensors, including amperometric, potentiometric, and impedimetric biosensors, and discusses the current challenges associated with biosensors for SARS-CoV-2 detection. The conclusion of this review discusses future directions in the field of electrochemical biosensors for SARS-CoV-2 detection, underscoring the importance of continued research and development in this domain.

Rapid antigen test in diagnosis of SARS-COV-2 in a specialized care facility Urology and Nephrology Center–Mansoura University-Egypt

Background: Polymerase chain reaction (PCR) is the benchmark in diagnosing of corona virus disease. It takes at least 4 hours. Multiple studies reported that rapid antigen test could be used. Their role in diagnosing corona virus disease 2019 (COVID-19) is questionable. This study was conducted to assess the accuracy of rapid antigen test in Urology and Nephrology Center Mansoura University, Egypt. Methods: COVID-19 rapid ag test was evaluated in comparison to real time PCR as a gold standard in diagnosis of COVID-19 infection in employees and patients with respiratory symptoms in specialized care facility Urology and Nephrology Center of Mansoura University from March 2020 till August 2021. Complete blood picture and non-contrast computerized tomography (CT) was done. Results: Eight hundred and eighty-four (884) individuals (median age 36 years) were included in this study: 478 healthcare workers, 217 non-healthcare workers, and 189 patients. PCR was positive in 569 samples and negative in 315. Out of 315 negative PCR samples, 8 were positive by rapid antigen test with a specificity of 97.4%. Conclusion: Rapid antigen tests in comparison to PCR test have a good accuracy in diagnosis in of COVID-19 infection and can be used during pandemics in low-resource areas. © 2020 The author (s). Published by Zagazig University.

Screening Hesitancy of a Universal Voluntary-based Rapid Antigen Test for coronavirus disease 2019 (COVID-19) During Omicron Wave in Hong Kong.

BACKGROUND: The Hong Kong government distributed rapid antigen test (RAT) kits to households across the city and called for a universal voluntary testing exercise for three consecutive days during the Omicron wave to identify infected persons early for quarantine and disrupt transmission chains in the community. We conducted a survey to evaluate the participation rates and explore the determinants of voluntary RAT adoption and hesitancy. METHODS: This cross-sectional survey was conducted through computer-assisted telephone interviews from 19 May to 16 June 2022 using an overlapping dual-frame telephone number sampling design. Information on willingness to adopt voluntary RAT, four themes of personal qualities, attitudes toward the government's health policies, incentives to motivate RAT adoption, and personal sociodemographic factors were collected. Logistic regression analysis was used to examine the factors associated with RAT adoption. RESULTS: Of the 1010 participants, 490 successfully responded to the fixed-line and 520 to the mobile phone survey, with response rates of 1.42% and 1.63% and screen hesitancy rates of 36.1% and 39.3%, respectively. Participants of adoption RAT were those aged 30-49 years, with high perceived COVID-19 infection severity, ≥ 3 doses of COVID-19 vaccination, and more agreement with the health policies on material resources and quarantine orders. Individuals who were less risk seeking and more altruistic reported a higher adoption of voluntary RAT. CONCLUSIONS: Understanding the willingness to participate in a voluntary universal testing programme might shed light on effective ways to minimise screening hesitancy in future public health strategies and campaigns.

Evaluation of "Test to Return" after COVID-19 Diagnosis in a Massachusetts Public School District.

BACKGROUND: Per Centers for Disease Control and Prevention guidance, students with COVID-19 may end isolation after 5 days if symptoms are improving; some individuals may still be contagious. Rapid antigen testing identifies possibly infectious virus. We report on a test-to-return (TTR) program in a Massachusetts school district to inform policy decisions about return to school after COVID-19. METHODS: During the 2021-2022 Omicron BA.1 surge, students with COVID-19 could return on day 6-10 if they met symptom criteria and had a negative rapid test; students with positive rapid tests and those who declined TTR remained isolated until day 11. TTR positivity rates were compared by grade level, vaccination status, symptom status, and day of infection. RESULTS: 31.4% of students had a positive TTR rapid test; there were no differences by grade or vaccination status. Ever-symptomatic students were more likely to have a positive rapid test (75/174 [43.1%] vs 18/104 [17.3%]). For ever-symptomatic students, TTR positivity decreased by day of infection. CONCLUSIONS: A substantial proportion of students may still be contagious 6 days after onset of COVID-19 infection. TTR programs may increase or reduce missed school days, depending on when return is otherwise allowed (day 6 or 11). The impact of TTR programs on school-associated transmission remains unknown.

Clinical features of COVID-19 rapid antigen test exposures reported by an Australian poisons information centre: a prospective study.

INTRODUCTION: Coronavirus disease COVID-19 rapid antigen tests are a useful tool in detecting infection, and their use has increased in many countries since they became commercially available in late 2021. Some rapid antigen tests contain sodium azide, which can be toxic in small doses. This study aimed to describe the clinical characteristics of exposures to COVID-19 rapid antigen tests. METHODS: This is a prospective study conducted by the New South Wales Poisons Information Centre. From 22 January 2022 to 31 August 2022, rapid antigen test exposures were followed up to obtain outcome information. Data collected included: brand/ingredients, exposure route, demographics, symptoms, and disposition. RESULTS: We recorded 218 exposures in the seven-month study period. Complete follow-up information was available in 75% (n = 164). There were 53 exposures to sodium azide-containing products (35 with follow-up data) and 165 to non-sodium azide-containing products and unknown ingredient exposures (129 with follow-up data). Overall, unintentional exposures predominated (n = 182), and 151 were ingestions. The vast majority (>90%) did not develop symptoms, and all symptoms that developed were mild. Most cases (95%, n = 208) did not require referral to a healthcare facility. CONCLUSIONS: In this prospective series, few patients developed symptoms, regardless of the sodium azide content, likely due to low concentration and low volume within the test kits. However, ongoing toxicovigilance is warranted.

Efficiency analysis of rapid antigen test based SARS-CoV-2 in hospital contact tracing and screening regime: test characteristics and cost effectiveness.

In the context of the current SARS-CoV-2 pandemic, reliable and cost-efficient screening and testing strategies are crucial to prevent disease transmission and reduce socioeconomic losses. To assess the efficiency of a rapid antigen test (RAT)-based SARS-CoV-2 contact-tracing and screening regime, we conducted a retrospective analysis of RAT and polymerase chain reaction (PCR) test data over a 1-year period, assessed test characteristics and estimated cost-effectiveness. The RAT had a sensitivity of 70.2% overall and 89.3% for people with a high risk of infectivity. We estimated inpatient treatment and quarantined healthcare worker costs of over € 5860.83, whereas the cost of identifying one SARS-CoV-2 positive person by RAT for our patient cohort was € 1210.75. In contrast, the estimated respective PCR cost was € 5043.32. Therefore, a RAT-based contract tracing and screening regime may be an efficient and cost-effective way to contribute to the early identification and prevention of SARS-CoV-2 transmission.

Evaluation of the new 2.0 version of the Roche SARS-CoV-2 Rapid Antigen Test.

We evaluated the new 2.0 version of the Roche Diagnostics SARS-CoV-2 Rapid Antigen Test (RAT 2.0) for the detection of SARS-CoV-2. Our evaluation material comprised of nasopharyngeal samples of 140 persons positive for SARS-CoV-2 nucleic acid amplification test (NAAT) and of 100 persons negative for SARS-CoV-2 NAAT. The sensitivity limit of the RAT 2.0 was further estimated with the additional selected samples of 27 persons with high NAAT cycle threshold (Ct) value representing low viral load. For the detection of possible cross-reactions in the RAT 2.0, routine respiratory samples positive for influenza A (N = 5), respiratory syncytial virus (RSV) (N = 4), or combined RSV and human coronavirus OC43 (N = 1) were included in the study material. The overall sensitivity of the RAT 2.0 was 92.1% and specificity 100%. When evaluating the samples with NAAT Ct value ≤ 30, the sensitivity was 97.0%. All samples for cross-reactivity testing containing other viruses instead of SARS-CoV-2 remained negative in RAT 2.0. According to our findings, this RAT 2.0 offers a reliable tool for the diagnostics of acute COVID-19 in this pandemic environment.

Sensitivity of rapid antigen tests for Omicron subvariants of SARS-CoV-2.

Diagnosis by rapid antigen tests (RATs) is useful for early initiation of antiviral treatment. Because RATs are easy to use, they can be adapted for self-testing. Several kinds of RATs approved for such use by the Japanese regulatory authority are available from drug stores and websites. Most RATs for COVID-19 are based on antibody detection of the SARS-CoV-2 N protein. Since Omicron and its subvariants have accumulated several amino acid substitutions in the N protein, such amino acid changes might affect the sensitivity of RATs. Here, we investigated the sensitivity of seven RATs available in Japan, six of which are approved for public use and one of which is approved for clinical use, for the detection of BA.5, BA.2.75, BF.7, XBB.1, and BQ.1.1, as well as the delta variant (B.1.627.2). All tested RATs detected the delta variant with a detection level between 7500 and 75 000 pfu per test, and all tested RATs showed similar sensitivity to the Omicron variant and its subvariants (BA.5, BA.2.75, BF.7, XBB.1, and BQ.1.1). Human saliva did not reduce the sensitivity of the RATs tested. Espline SARS-CoV-2 N showed the highest sensitivity followed by Inspecter KOWA SARS-CoV-2 and V Trust SARS-CoV-2 Ag. Since the RATs failed to detect low levels of infectious virus, individuals whose specimens contained less infectious virus than the detection limit would be considered negative. Therefore, it is important to note that RATs may miss individuals shedding low levels of infectious virus.

SARS-CoV-2 antigen detection by saliva; an alternative to nasopharyngeal specimen: A cross-sectional study.

Background and Aims: Saliva samples are less invasive and more convenient for patients than naso- and/or oropharynx swabs (NOS). However, there is no US Food and Drug Administration-approved severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) rapid antigen test kit, which can be useful in a prolonged pandemic to reduce transmission by allowing suspected individuals to self-sampling. We evaluated the performances of High sensitive AQ+ Rapid SARS-CoV-2 Antigen Test (AQ+ kit) using nasopharyngeal swabs (NPs) and saliva specimens from the same patients in laboratory conditions. Methods: The real-time reverse transcription-polymerase chain reaction (rRT-PCR) test result was used for screening the inrolled individuals and compared as the gold standard. NP and saliva samples were collected from 100 rRT-PCR positives and 100 negative individuals and tested with an AQ+ kit. Results: The AQ+ kit showed good performances in both NP and saliva samples with an overall accuracy of 98.5% and 94.0%, and sensitivity of 97.0% and 88.0%, respectively. In both cases, specificity was 100%. AQ+ kit performance with saliva was in the range of the World Health Organization recommended value. Conclusion: xOur findings indicate that the saliva specimen can be used as an alternative and less invasive to NPs for quick and reliable SARS-CoV-2 antigen detection.

Clinical evaluation of anterior nasal cavity swab specimens by a rapid antigen test using a GLINE-2019-nCoV Ag Kit to diagnose COVID-19.

The promising diagnostic performance of rapid antigen tests (RATs) using non-invasive anterior nasal (AN) swab specimens to diagnose COVID-19 has been reported. A large number of RATs are commercially available; however, the careful assessment of RATs is essential prior to their implementation in clinical practice. We evaluated the clinical performance of the GLINE-2019-nCoV Ag Kit as a RAT using AN swabs in a prospective, blinded study. Adult patients who visited outpatient departments and received SARS-CoV-2 tests between August 16 and September 8, 2022, were eligible for this study. Patients who were aged under 18 years and patients without appropriate specimens were excluded. Two sets of AN and nasopharyngeal (NP) swabs were collected from all patients. Each set of specimens was tested by the RAT and quantitative reverse-transcription polymerase chain reaction (RT-qPCR). Of the 138 recruited patients, 84 were positive and 54 were negative by RT-qPCR using NP swabs. The positive agreement rate between RT-qPCR using NP swabs and RAT using AN swabs was 78.6% (95% confidence interval [CI], 68.3%-86.8%), the negative agreement rate was 98.1% (95% CI, 90.1%-99.9%), and the overall agreement rate was 86.2% (95% CI, 79.3%-91.5%), with a κ coefficient of 0.73. The positive agreement rate in the early phase (≤3 days from symptom onset) was >80%, but this fell to 50% in the late phase (≥4 days). This study demonstrates that the GLINE-2019-nCoV Ag Kit using AN swabs has good clinical performance and might be a reliable alternative method for diagnosing COVID-19.

A Reagent and Virus Benchmarking Panel for a Uniform Analytical Performance Assessment of N Antigen-Based Diagnostic Tests for COVID-19.

Rapid diagnostic tests (RDTs) that detect antigen indicative of severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) infection can help in making quick health care decisions and regularly monitoring groups at risk of infection. With many RDT products entering the market, it is important to rapidly evaluate their relative performance. Comparison of clinical evaluation study results is challenged by protocol design variations and study populations. Laboratory assays were developed to quantify nucleocapsid (N) and spike (S) SARS-CoV-2 antigens. Quantification of the two antigens in nasal eluates confirmed higher abundance of N than S antigen. The median concentration of N antigen was 10 times greater than S per genome equivalent. The N antigen assay was used in combination with quantitative reverse transcription (RT)-PCR to qualify a panel composed of recombinant antigens, inactivated virus, and clinical specimen pools. This benchmarking panel was applied to evaluate the analytical performance of the SD Biosensor Standard Q COVID-19 antigen (Ag) test, Abbott Panbio COVID-19 Ag rapid test, Abbott BinaxNOW COVID-19 Ag test, and the LumiraDx SARS-CoV-2 Ag test. The four tests displayed different sensitivities toward the different panel members, but all performed best with the clinical specimen pool. The concentration for a 90% probability of detection across the four tests ranged from 21 to 102 pg/mL of N antigen in the extracted sample. Benchmarking panels provide a quick way to verify the baseline performance of a diagnostic and enable direct comparisons between diagnostic tests. IMPORTANCE This study reports the results for severe acute respiratory syndrome coronavirus-2 (SARS-COV-2) nucleocapsid (N) and spike (S) antigen quantification assays and their performance against clinical reverse transcription (RT)-PCR results, thus describing an open-access quantification method for two important SARS-CoV-2 protein analytes. Characterized N antigen panels were used to evaluate the limits of detection of four different rapid tests for SARS-CoV-2 against multiple sources of nucleocapsid antigen, demonstrating proof-of-concept materials and methodology to evaluate SARS-CoV-2 rapid antigen detection tests. Quantification of N antigen was used to characterize the relationship between viral count and antigen concentration among clinical samples and panel members of both clinical sample and viral culture origin. This contributes to a deeper understanding of protein antigen and molecular analytes and presents analytical methods complementary to clinical evaluation for characterizing the performance of both laboratory-based and point-of-care rapid diagnostics for SARS-CoV-2.

Expert Consensus on Rapid SARS-CoV-2 Antigen Testing.

The epidemic of the highly contagious, long lasting and widely popular coronavirus disease 2019 (COVID-19) has imposed a huge burden to the global public health. As one of the key methods for early diagnosis of COVID-19 infection, rapid acute respiratory syndrome coronavirus 2 (SARS-CoV-2) antigen testing has been gradually applied in China. To address concerns raised by both health care workers and the public, based on the latest research and clinical practices, the Sub-committee of the Clinical Microbiology Laboratory of the Chinese Hospital Association proposed"Expert Consensus on Rapid SARS-CoV-2 Antigen Testing(2022)". The consensus panel is composed of experts from multiple disciplines, including laboratory medicine, clinical medicine, infection control, public health, research and development of in vitro diagnostic products. The consensus describes its principle, technological characteristics, results interpretation and, disposal recommendations, and analyzes the strategies and matters needing attention in different application scenarios. We expect the consensus to help correct understanding and application of rapid SARS-CoV-2 antigen testing in the diagnosis, treatment, prevention, and control of COVID-19.Copyright © 2022, Peking Union Medical College Hospital. All rights reserved.

Rapid Detection of Sars Cov-2 Infection in Comparision with Rt-Pcr in Tertiary Care Hospital

Objectives: The goal of the present study was to assess the SARS-CoV-2 antigen detection test's performance features and compare them to the real-time reverse transcription polymerase chain reaction (RT-PCR) test, the gold standard test for the diagnosis of COVID-19 cases. Method(s): From October 2020 to May 2021, patients attending the OPD, including those undergoing surgery, at a Tertiary Care Teaching Hospital in Telangana provided 1000 respiratory samples, primarily nasopharyngeal swabs. A skilled technician had collected two nasopharyngeal swabs from each person in a COVID sample collection room while wearing personal protective equipment and following strict infection control procedures. One swab was used for the rapid antigen test given by the standard Q COVID-19 Ag test kit and placed into the extraction buffer tube. Second swab was kept in the viral transport medium and used for AllplexTM 2019-nCoV Assay (Seegene, Korea), which targets envelope gene (E), and RNA dependent RNA polymerase (RdRp) and nucleocapsid (N) genes of SARS CoV-2, was used for SARS-CoV-2 RNA detection according to the manufacturer's instructions. Result(s): Out of 1000 samples tested for COVID-19, 623 (63.7%) were males and 377 (36.3%) were females. Out of 1000 samples, 347 samples were RT-PCR positive and 653 were RT-PCR negative. Out of 347 RT-PCR samples positive, 341 were Rapid antigen test positive samples and six were negative. Overall sensitivity and specificity are 98.27% and 99.85%, respectively. Conclusion(s): The real-time RT-PCR assay's sensitivity and specificity were comparable to those of the rapid assay for SARS-CoV-2 antigen detection. It can be utilized for contact tracing measures to control the COVID-19 pandemic in places such as border crossings, airports, interregional bus and train stations, and mass testing campaigns needing quick findings. This is especially true in areas with a high prevalence of the disease.Copyright © 2023 The Authors. Published by Innovare Academic Sciences Pvt Ltd.

Should rapid antigen tests be first-line for COVID-19 testing? Results of a prospective urban cohort study.

BACKGROUND: A highly accurate, rapid, and low-cost COVID-19 test is essential for guiding isolation measures. To date, the most widely used tests are either nucleic acid amplification tests or antigen tests. The objective of this study is to further assess the diagnostic performance of the Binax-CoV2 rapid antigen test in comparison to the current gold standard reverse transcription quantitative polymerase chain reaction (RT-qPCR), with additional analysis of symptomatology and cycle threshold utility. METHODS: This is a prospective cohort study performed between November and December 2020. Individuals who presented to COVID-19 testing events and received both RT-qPCR and a rapid antigent test were included. Testing occurred at the emergency department of an urban hospital and at a community mobile unit. No fees or appointments were required. Individuals self-reported the presence or absence of symptoms and history of positive COVID-19 test within the previous two weeks. Trained staff collected two subsequent nasopharyngeal swabs of both nares. One set of swabs underwent RT-qPCR and the other underwent Binax-CoV2 assay per manufacturer guidelines. RESULTS: A total of 390 patients were included, of which 302 were from the community site. Of these 302, 42 (14%) were RT-qPCR positive. Of the 42 RT-qPCR positive, 30 (71.4%) were also positive by Binax-CoV2. The Binax-CoV2 test had a sensitivity of 71.4% (95% CI: 55%-84%) and a specificity of 99.6% (95% CI: 98%-100%) in this population. Performance of the Binax-CoV2 test performed better in individuals with higher viral load. For symptomatic patients with cycle threshold < 20, sensitivity reached 100%. CONCLUSIONS: The Binax-CoV2 assay's specificity and sensitivity in individuals with high viral load makes it a suitable first-line test for detecting COVID-19. However, given the assay's measured sensitivity, a negative result on the Binax-CoV2 assay may warrant additional testing with more sensitive tests, such as the RT-qPCR. This is particularly the case with high clinical suspicion for an active SARS-CoV-2 infection even after a negative Binax-CoV2 result.

Use of Rapid Antigen Tests to End Isolation in a University Setting: Observational Study.

BACKGROUND: COVID-19 isolation recommendations have evolved over the course of the pandemic. Initially, the US Centers for Disease Control and Prevention required 10 days of isolation after a positive test result. In December 2021, this was reduced to a minimum of 5 days with symptom improvement, followed by 5 days of mask wearing. As a result, several institutions of higher education, including the George Washington University, required persons testing positive for COVID-19 to either submit a negative rapid antigen test (RAT) with symptom resolution to leave isolation after 5 days or to maintain a 10-day isolation period in the absence of a negative RAT and the presence of continued symptoms. RATs are tools that can be used both to shorten isolation periods and to ensure that persons testing positive for COVID-19 remain in isolation if infectious. OBJECTIVE: The purpose of this analysis is to report on the experience of implementing RAT policies, examine the number of days that isolation was reduced via RAT testing, determine the factors that predicted uploading a RAT, and determine RAT positivity percentages to illustrate the utility of using RATs to end isolation. METHODS: In this study, 880 individuals in COVID-19 isolation at a university in Washington, DC, uploaded 887 RATs between February 21 and April 14, 2022. Daily positivity percentages were calculated, and multiple logistic regression analyses examined the odds of uploading a RAT by campus residential living status (ie, on or off campus), student or employee designation, age, and days in isolation. RESULTS: A total of 76% (669/880) of individuals in isolation uploaded a RAT during the study period. Overall, 38.6% (342/887) of uploaded RATs were positive. Uploaded RATs were positive 45.6% (118/259) of the time on day 5; 45.4% (55/121) on day 6; 47.1% (99/210) on day 7; and 11.1% (7/63) on day 10 or beyond. Adjusted logistic regression modeling indicated cases living on campus had increased odds of uploading a RAT (odds ratio [OR] 2.54, 95% CI 1.64-3.92), whereas primary student affiliation (OR 0.29, 95% CI 0.12-0.69) and days in isolation (OR 0.45, 95% CI 0.39-0.52) had decreased odds of uploading a RAT. Of the 545 cases with a negative RAT, 477 were cleared prior to day 10 of their isolation due to lack of symptoms and timely submission, resulting in a total of 1547 days of lost productivity saved compared to all being in isolation for 10 days. CONCLUSIONS: RATs are beneficial, as they can support a decision to release individuals from isolation when they have recovered and maintain isolation for people who may still be infectious. Future isolation policies should be guided by similar protocols and research to reduce the spread of COVID-19 and minimize lost productivity and disruption to individuals' lives.

Rapid Antigen Tests during the COVID-19 Era in Korea and Their Implementation as a Detection Tool for Other Infectious Diseases.

Rapid antigen tests (RATs) are diagnostic tools developed to specifically detect a certain protein of infectious agents (viruses, bacteria, or parasites). RATs are easily accessible due to their rapidity and simplicity. During the COVID-19 pandemic, RATs have been widely used in detecting the presence of the specific SARS-CoV-2 antigen in respiratory samples from suspected individuals. Here, the authors review the application of RATs as detection tools for COVID-19, particularly in Korea, as well as for several other infectious diseases. To address these issues, we present general knowledge on the design of RATs that adopt the lateral flow immunoassay for the detection of the analyte (antigen). The authors then discuss the clinical utilization of the authorized RATs amidst the battle against the COVID-19 pandemic in Korea and their role in comparison with other detection methods. We also discuss the implementation of RATs for other, non-COVID-19 infectious diseases, the challenges that may arise during the application, the limitations of RATs as clinical detection tools, as well as the possible problem solving for those challenges to maximize the performance of RATs and avoiding any misinterpretation of the test result.

Evaluation of Four Rapid Antigen Tests for the Detection of SARS-CoV-2 Infection with Nasopharyngeal Swabs.

Owing to the high transmissibility of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) variants, the capacity of testing systems based on the gold standard real-time reverse transcription-polymerase chain reaction (rRT-PCR) is limited. Rapid antigen tests (RATs) can substantially contribute to the prevention of community transmission, but their further assessment is required. Here, using 1503 nasopharyngeal swabs, we compared the diagnostic performance of four RAT kits (Abbott Panbio™ COVID-19 Ag Rapid Test, SD Biosensor Standard™ Q COVID-19 Ag Test, Humasis COVID-19 Ag Test, and SG Medical Acrosis COVID-19 Ag Test) to the cycle threshold (Ct) values obtained from rRT-PCR. The precision values, area under the curve values, SARS-CoV-2 variant detection ability, and non-SARS-CoV-2 specificity of all four kits were similar. An assay using the Acrosis kit had a significantly better positive detection rate with a higher recall value and cut-off value than that using the other three RAT kits. During the current COVID-19 pandemic, the Acrosis kit is an effective tool to prevent the spread of SARS-CoV-2 in communities.

Performance characteristics of the boson rapid SARS-cov-2 antigen test card vs RT-PCR: Cross-reactivity and emerging variants.

Background: SARS-CoV-2 virus has undergone several mutations on its genome, since the onset of the pandemic. Multiple variants of concern (VOC) have emerged including Alpha, Beta, Gamma, and Delta with the more recent one being the Omicron (B.1.1.529). Specific rapid antigen tests (RADs) have been used for the detection of SARS-CoV-2. However, since the emergence of new VOCs, the performance characteristics of these RADs needs to be re-evaluated. Objectives: The main purposes of this clinical study were to determine the diagnostic sensitivity and specificity of the BOSON Rapid Antigen Test compared to the gold standard real time RT-PCR and to determine the ability of the RAD to accurately depict different VOC. Additionally, the cross reactivity to other viruses and pathogen, as well as, the possible interference of non Covid-19 hospitalized patients for various causes, were investigated. Results: A total of 623 individuals (symptomatic) were tested. The sensitivity, specificity and accuracy of the BOSON RAD was 95.27%, 100% and 98.45% (n = 448), meeting the WHO recommended standards. Additionally, the Delta (83.33%, Ct < 34) and Omicron (100%, Ct < 26) VOC were determined with high sensitivity. Also, there was no interference from hospitalized, non-Covid 19 patients, and no cross-reactivity was detected. Conclusions: The study showed that this RAD could rapidly identify individuals with SARS-CoV-2, including those with the new dominant Omicron VOC, with no cross reactivity from other pathogens.

Influence of seasonal and operator variations on diagnostic accuracy of lateral flow devices during the COVID-19 pandemic: a systematic review and meta-analysis.

BACKGROUND: Lateral flow tests (LFT) are point-of-care rapid antigen tests that allow isolation and control of disease outbreaks through convenient, practical testing. However, studies have shown significant variation in their diagnostic accuracy. We conducted a systematic review of the diagnostic accuracy of LFTs for the detection of severe acute respiratory syndrome-coronavirus 2 (SARS-CoV-2) to identify potential factors affecting their performance. METHODS: A systematic search of online databases was carried out to identify studies assessing the sensitivity and specificity of LFTs compared with polymerase chain reaction (PCR) tests. Data were extracted and used to calculate pooled sensitivity and specificity. Meta-regression analysis was conducted to identify covariates influencing diagnostic accuracy. RESULTS: In total, 76 articles with 108,820 test results were identified for analysis. Pooled sensitivity and specificity were 72% (95% confidence interval (CI): 0.68-0.76) and 100% (95% CI: 0.99-1.00), respectively. Staff operation of the LFT showed a statistically significant increase in sensitivity (p=0.04) and specificity (p=0.001) compared with self-operation by the test subjects. The use of LFTs in symptomatic patient subgroups also resulted in higher test sensitivity. CONCLUSION: LFTs display good sensitivity and extremely good specificity for SARS-CoV-2 antigen detection; they become more sensitive in patients with symptoms and when performed by trained professionals.

Sequencing directly from antigen-detection rapid diagnostic tests in Belgium, 2022: a gamechanger in genomic surveillance?

BackgroundLateral flow antigen-detection rapid diagnostic tests (Ag-RDTs) for viral infections constitute a fast, cheap and reliable alternative to nucleic acid amplification tests (NAATs). Whereas leftover material from NAATs can be employed for genomic analysis of positive samples, there is a paucity of information on whether viral genetic characterisation can be achieved from archived Ag-RDTs.AimTo evaluate the possibility of retrieving leftover material of several viruses from a range of Ag-RDTs, for molecular genetic analysis.MethodsArchived Ag-RDTs which had been stored for up to 3 months at room temperature were used to extract viral nucleic acids for subsequent RT-qPCR, Sanger sequencing and Nanopore whole genome sequencing. The effects of brands of Ag-RDT and of various ways to prepare Ag-RDT material were evaluated.ResultsSARS-CoV-2 nucleic acids were successfully extracted and sequenced from nine different brands of Ag-RDTs for SARS-CoV-2, and for five of these, after storage for 3 months at room temperature. The approach also worked for Ag-RDTs for influenza virus (n = 3 brands), as well as for rotavirus and adenovirus 40/41 (n = 1 brand). The buffer of the Ag-RDT had an important influence on viral RNA yield from the test strip and the efficiency of subsequent sequencing.ConclusionOur finding that the test strip in Ag-RDTs is suited to preserve viral genomic material, even for several months at room temperature, and therefore can serve as source material for genetic characterisation could help improve global coverage of genomic surveillance for SARS-CoV-2 as well as for other viruses.