Analytical and clinical evaluation of a point-of-care molecular diagnostic system and its influenza A/B assay for rapid molecular detection of the influenza virus

Direct and Ultrasensitive Bioluminescent Detection of Intact Respiratory Viruses

Respiratory viruses such as SARS-CoV-2, influenza, and respiratory syncytial virus (RSV) represent pressing health risks. Rapid diagnostic tests for these viruses detect single antigens or nucleic acids, which do not necessarily correlate with the amount of the intact virus. Instead, specific detection of intact respiratory virus particles may be more effective at assessing the contagiousness of a patient. Here, we report GLOVID, a modular biosensor platform to detect intact virions against a background of "free" viral proteins in solution. Our approach harnesses the multivalent display of distinct proteins on the surface of a viral particle to template the reconstitution of a split luciferase, allowing specific, single-step detection of intact influenza A and RSV virions corresponding to 0.1-0.3 fM of genomic units. The protein ligation system used to assemble GLOVID sensors is compatible with a broad range of binding domains, including nanobodies, scFv fragments, and cyclic peptides, which allows straightforward adjustment of the sensor platform to target different viruses.

Development of a mobile laboratory system in hydrogen fuel cell buses and evaluation of the performance for COVID-19 RT-PCR testing

We designed and developed two new types of hydrogen fuel cell (HFC) buses (motorcoach and minibus) with a mobile laboratory system. Feasibility studies have been performed for mobile laboratory testing, particularly for the laboratory performance of COVID-19 RT-PCR (PCR). We evaluated the driving range capability, PCR sample size capacity, turnaround time (TAT), and analytical performance for the detection of SARS-CoV-2. Saliva samples were used for the current study, and the analytical performance was compared with that of the reference PCR. The estimated driving range and sample size capacity of the HFC and HFC minibus were 432 km and 2847 samples, respectively, for the HFC motorcoach and 313 km and 1949 samples for the HFC minibus. For the TAT, the median time between sample submission and completion of PCR was 86 min for the motorcoach and 76 min for the minibus, and the median time between sample submission and electronic reporting of the result to each visitor was 182 min for the motorcoach and 194 min for the minibus. A secondary analysis of 1574 HFC mobile laboratory testing samples was conducted, and all negative samples were found to be negative by reference PCR. Furthermore, all samples were confirmed to be positive by reference PCR or other molecular examinations.

Symptomatic Differences between Influenza A/H3N2 and A/H1N1 in Korea

BACKGROUND

Limited understanding exists regarding clinical distinctions between influenza A/H3N2 and A/H1N1 subtypes, particularly in primary health care. We conducted a comparative analysis of symptomatic characteristics of influenza subtypes in Korea. This retrospective study analyzed medical records of patients who presented with positive test results for influenza-like illness (rapid influenza diagnostic test; RIDT) during the H3N2-dominant 2016-2017 and H1N1-dominant 2018-2019 seasons. Symptomatic manifestations, contact history, vaccination history, and clinical course were analyzed between the two seasons. The most frequent symptom in the RIDT-positive patients was fever (80.1% and 79.1%, respectively). The average body temperature was higher, and the number of patients with high fever was greater in the H3N2-dominant season than in the H1N1-dominant season (p < 0.001). Conversely, other symptoms, such as myalgia, cough, and sore throat, were significantly more common in the H1N1-dominant season than in the H3N2-dominant season (p < 0.001). Antiviral drugs were prescribed to most febrile RIDT-positive patients (82.2% and 81.3%, respectively, p = 0.516). Analyzing primary care data revealed different clinical manifestations according to the subtype. Therefore, physicians should consider these variable hallmarks and employ tailored therapeutic strategies to reduce the complication rate.

Clinical Performance of the cobas Liat SARS-CoV-2 & Influenza A/B Assay in Nasal Samples

Background and Objective

Point-of-care type molecular diagnostic tests have been used for detecting SARS-CoV-2, although their clinical utility with nasal samples has yet to be established. This study evaluated the clinical performance of the cobas Liat SARS-CoV-2 & Influenza A/B (Liat) assay in nasal samples.

Methods

Nasal and nasopharyngeal samples were collected and were tested using the Liat, the cobas 6800 system and the cobas SARS-CoV-2 & Influenza A/B (cobas), and a method developed by National Institute of Infectious Diseases, Japan (NIID).

Results

A total of 814 nasal samples were collected. The Liat assay was positive for SARS-CoV-2 in 113 (13.9%). The total, positive, and negative concordance rate between the Liat and cobas/NIID assays were 99.3%/98.4%, 99.1%/100%, and 99.3%/98.2%, respectively. Five samples were positive only using the Liat assay. Their Ct values ranged from 31.9 to 37.2. The Ct values of the Liat assay were significantly lower (p < 0.001) but were correlated (p < 0.001) with those of other molecular assays. In the participants who tested positive for SARS-CoV-2 on the Liat assay using nasopharyngeal samples, 88.2% of their nasal samples also tested positive using the Liat assay.

Conclusion

The Liat assay showed high concordance with other molecular assays in nasal samples. Some discordance occurred in samples with Ct values > 30 on the Liat assay.

Supplementary Information

The online version contains supplementary material available at 10.1007/s40291-022-00580-8.

Diagnostic performance of rapid antigen test for COVID-19 and the effect of viral load, sampling time, subject's clinical and laboratory parameters on test accuracy

Background

Egypt was among the first 10 countries in Africa that experienced COVID-19 cases. The sudden surge in the number of cases is overwhelming the capacity of the national healthcare system, particularly in developing countries. Central to the containment of the ongoing pandemic is the availability of rapid and accurate diagnostic tests that could pinpoint patients at early disease stages. In the current study, we aimed to (1) Evaluate the diagnostic performance of the rapid antigen test (RAT) “Standard™ Q COVID-19 Ag” against reverse transcriptase quantitative real-time PCR (RT-qPCR) in eighty-three swabs collected from COVID-19 suspected individuals showing various demographic features, clinical and radiological findings. (2) Test whether measuring laboratory parameters in participant’s blood would enhance the predictive accuracy of RAT. (3) Identify the most important features that determine the results of both RAT and RT-qPCR.

Methods

Diagnostic measurements (e.g. sensitivity, specificity, etc.) and receiver operating characteristic curve were used to assess the clinical performance of “Standard™ Q COVID-19 Ag”. We used the support vector machine (SVM) model to investigate whether measuring laboratory indices would enhance the accuracy of RAT. Moreover, a random forest classification model was used to determine the most important determinants of the results of RAT and RT-qPCR for COVID-19 diagnosis.

Results

The sensitivity, specificity, and accuracy of RAT were 78.2, 64.2, and 75.9%, respectively. Samples with high viral load and those that were collected within one-week post-symptoms showed the highest sensitivity and accuracy. The SVM modeling showed that measuring laboratory indices did not enhance the predictive accuracy of RAT.

Conclusion

“Standard™ Q COVID-19 Ag” should not be used alone for COVID-19 diagnosis due to its low diagnostic performance relative to the RT-qPCR. RAT is best used at the early disease stage and in patients with high viral load.

A Prospective Evaluation of the Analytical Performance of GENECUBE® HQ SARS-CoV-2 and GENECUBE® FLU A/B

Background

Molecular tests are the mainstay of detecting severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). However, their accessibility can be limited by the long examination time and inability to evaluate multiple samples at once.

Objective

This study evaluated the analytical performance of the newly developed rapid molecular assays GENECUBE^® HQ SARS-CoV-2 and GENECUBE^® FLU A/B.

Method

This prospective study was conducted between 14 December 2020 and 9 January 2021 at a polymerase chain reaction (PCR) center. Samples were collected from the nasopharynx with flocked swabs. Molecular tests were performed with the GENECUBE^® system and reference reverse transcription (RT)-PCR, and the results of the two assays were compared.

Result

Among 1065 samples, 81 (7.6%) were positive for SARS-CoV-2 on the reference RT-PCR. Three showed discordance between GENECUBE^® HQ SARS-CoV-2 and the reference RT-PCR; the total, positive, and negative samples of concordance for the two assays were 99.7%, 100%, and 99.7%, respectively. All discordant cases were positive with GENECUBE^® HQ SARS-CoV-2 and negative with the reference RT-PCR. SARS-CoV-2 was detected in all three samples using another molecular assay for SARS-CoV-2. For GENECUBE^® FLU A/B, the total, positive, and negative samples of concordance for the two assays were 99.5%, 100%, and 99.1%.

Conclusion

The GENECUBE^® HQ SARS-CoV-2 and GENECUBE^® FLU A/B demonstrated sufficient analytical performance to detect SARS-CoV-2 and influenza virus A/B.

Supplementary Information

The online version contains supplementary material available at 10.1007/s40291-021-00535-5.

Diagnosis of respiratory syncytial virus and influenza A and B with cobas® Liat® from nasopharyngeal aspirations in pediatrics

The cobas® Liat® Influenza A/B and respiratory syncytial virus assay was tested on nasopharyngeal aspirates. The resolution of invalid samples was performed using a preanalytical step. cobas® Liat® can be used on nasopharyngeal aspirates with a preanalytical processing step, with a slightly diminished performances in detecting respiratory syncytial virus but not for influenza.

Performance and ease of use of a molecular point-of-care test for influenza A/B and RSV in patients presenting to primary care

Annual influenza epidemics cause substantial morbidity and mortality, and the majority of patients with influenza-like illness present to primary care. Point-of-care influenza tests could support treatment decisions. It is critical to establish analytic performance of these platforms in real-life patient samples before uptake can be considered. We aimed to assess the analytical performance and ease of use of the cobas® Liat® PCR POCT in detecting influenza A/B and RSV in samples collected from patients with influenza-like illness in primary care. Sensitivity and specificity of the cobas® Liat® POCT are calculated in comparison with a commercial laboratory-based PCR test (Fast-Track Respiratory Pathogens 21 Plus kit (Fast-Track Diagnostics)). Samples with discordant results were analysed additionally by the RespiFinder 2Smart (PathoFinder) using an Extended Gold Standard (EGS). Acceptability was scored on a five-point Likert scale as well as a failure mode analysis of the cobas® Liat® POCT was performed. Nasal and oropharyngeal swabs were obtained from 140 children and nasopharyngeal swabs from 604 adults (744 patients). The cobas® Liat® POCT had a sensitivity and specificity of 100% (95% CI 99-100%) and 98.1% (95%CI 96.3-99%) for influenza A, 100% (95% CI 97.7-100%) and 99.7% (95%CI 98.7-99.9%) for influenza B and 100% (95% CI 87.1-100%) and 99.4% (95%CI 98.6-99.8%) for RSV, respectively. According to trained lab technicians, the cobas® Liat® POCT was considered easy-to-use, with a fast turn-around-time. Cobas® Liat® POCT is a promising decentralised test platform for influenza A/B and RSV in primary care as it provides fairly rapid results with excellent analytic performance. Point-of-care influenza tests could support treatment decisions in primary care. Cobas® Liat® POCT is a promising decentralised test platform for influenza A/B and RSV in primary care as it provides fairly rapid results with excellent analytic performance.

Cost evaluation of point-of-care testing for community-acquired influenza in adults presenting to the emergency department

BACKGROUND

Rapid molecular point-of-care tests (POCTs) for influenza have potential to produce cost savings in emergency departments (EDs) and acute care settings. To date, published projected savings have been based on estimated costs.

OBJECTIVES

This study aimed to describe the cost implications of a rapid influenza POCT using accurate real-world patient level costing data. 204 adult patients receiving point-of-care (POC) influenza testing in the ED as part of a routine clinical service were identified retrospectively, alongside a control cohort of 104 patients from the same influenza season. Costs for all were calculated at the individual patient level. Cost comparison was performed using an instrumental variable (IV) regression to overcome potential bias within the observational dataset.

RESULTS

Patients who had a POCT on average cost 67 % less than those who did not (average cost reduction: £2066: 95 % CI: £624 and £2665). Moderate to high NEWS score at arrival, presence of ≥1 comorbidity, and age ≥70 years increased overall costs across both groups (p < 0.05).

CONCLUSIONS

Savings from POC testing can be attributed to more targeted treatments, fewer admissions and reduced lengths of stay. The IV regression results are supported by a second method (ordinary least square against baseline characteristics). They are also in line with existing work that use estimated costs but indicate greater savings than predicted previously. In conclusion, POC influenza testing in the emergency department produces significant cost savings, this is demonstrated here through an analysis using individual real-world patient level costing data.