ABSTRACT
OBJECTIVE: To determine the sensitivity and specificity of the Abbott ID-NOW™ test in the diagnosis of COVID-19. The test is based on the detection of the SARS-CoV-2 gene by isothermal amplification technology. METHODS: From 303 individuals, two nasopharyngeal swabs and one oropharyngeal swab were collected to be tested in parallel by the ID-NOW™ test and PCR test (Allplex™ SARS-CoV-2 Assay). A subgroup of 107 individuals presented to the public collection point for covid-19 at the Motol University Hospital during the dominance of the Delta variant, and the others were tested via the Adult Emergency Admission Department during the dominance of the Omicron variant. RESULTS: Of 297 valid samples, 43 were positive by the PCR assay and 33 were positive by the ID-NOW™ test (sensitivity 76.74%; 95% CI 61.37 to 88.24%). ID-NOW™ detected three samples as positive, but the positivity was not confirmed by PCR (specificity 98.82%; 95% CI 96.59 to 99.76%). A significant increase in sensitivity up to 100% is observed for samples with a higher viral load (with a PCR threshold cycle value below 30 or from patients with symptoms of COVID-19). The Delta or Omicron variant has no significant effect on the sensitivity of the test. CONCLUSION: Due to its ease of use and speed of result, ID-NOW™ is a suitable diagnostic tool for prompt assessment of a patient's infectivity. If, despite the negative ID-NOW™ result, the patient has symptoms of COVID-19, it is advised to perform a classic PCR test for SARS-CoV-2.
Subject(s)
COVID-19 , SARS-CoV-2 , Adult , Humans , SARS-CoV-2/genetics , COVID-19/diagnosis , COVID-19 Testing , Clinical Laboratory Techniques , Sensitivity and SpecificityABSTRACT
Aim: The test, based on the detection of SARS-CoV-2 antigen, is often seen as an alternative to the PCR method in connection with the need for screening of larger populations. In order to assess the suitability of such an approach, we evaluated the sensitivity of two antigenic assays on a group of individuals, including both patients with symptoms of covid-19 and asymptomatic and healthy individuals.
ABSTRACT
An attempt is undertaken to chemically modify YMnO3+delta by the partial substitution of Y with larger Nd and Sm, aiming to boost the oxygen storage performance in the temperature swing process. Single-phase (P6(3)cm) Y0.95Nd0.05MnO3+delta and Y0.95Sm0.05MnO3+delta compounds are obtained in a sol-gel auto-combustion process followed by the annealing at 1000 degrees C in Ar. Both materials show improved oxygen storage capacity, however, doping with Nd3+ enables the effective operation in air - capacity reached 1453 mu mol-O g(-1), which is over 86% of the capacity in O-2. As documented for the Nd-containing sample, oxygen absorption is accompanied by oxidation of Mn(3+)to Mn4+, and no changes in the valence of neodymium occur. The reversible oxygen intake and release occur at exceptionally low temperatures for Y0.95Nd0.05MnO3+delta, as low as in the 201-240 degrees C range. This enables utilization of the recovery of low-and medium-temperature waste heat. In addition, the paper presents the impact of the preparation route of the material on the oxygen storage-related performance. It is shown that lowering of the annealing temperature allows to further increase the rate of O-2 absorption, making the material a promising candidate for practical application, however, it results also in the presence of the secondary phases. (C) 2021 The Authors. Published by Elsevier Ltd.
ABSTRACT
An attempt is undertaken to chemically modify YMnO3+δ by the partial substitution of Y with larger Nd and Sm, aiming to boost the oxygen storage performance in the temperature swing process. Single-phase (P63cm) Y0.95Nd0.05MnO3+δ and Y0.95Sm0.05MnO3+δ compounds are obtained in a sol-gel auto-combustion process followed by the annealing at 1000 °C in Ar. Both materials show improved oxygen storage capacity, however, doping with Nd3+ enables the effective operation in air – capacity reached 1453 μmol-O g−1, which is over 86% of the capacity in O2. As documented for the Nd-containing sample, oxygen absorption is accompanied by oxidation of Mn3+ to Mn4+, and no changes in the valence of neodymium occur. The reversible oxygen intake and release occur at exceptionally low temperatures for Y0.95Nd0.05MnO3+δ, as low as in the 201–240 °C range. This enables utilization of the recovery of low- and medium-temperature waste heat. In addition, the paper presents the impact of the preparation route of the material on the oxygen storage-related performance. It is shown that lowering of the annealing temperature allows to further increase the rate of O2 absorption, making the material a promising candidate for practical application, however, it results also in the presence of the secondary phases. © 2021 The Authors
ABSTRACT
OBJECTIVES: Antigen tests have emerged as an alternative to SARS-CoV-2 diagnostic PCR, thought to be valuable especially for the screening of bigger communities. To check appropriateness of the antigen based testing, we determined sensitivity of two point-of-care antigen tests when applied to a cohort of COVID-19 symptomatic, COVID-19 asymptomatic and healthy persons. METHODS: We examined nasopharyngeal swabs with antigen test 1 (Panbio Covid-19 Ag Rapid Test, Abbott) and antigen test 2 (Standard F Covid-19 Ag FIA, SD Biosensor). An additional nasopharyngeal and oropharyngeal swab of the same individual was checked with PCR (Allplex SARS-nCoV-2, Seegene). Within a 4-day period in October 2020, we collected specimens from 591 subjects. Of them, 290 had COVID-19 associated symptoms. RESULTS: While PCR positivity was detected in 223 cases, antigen test 1 and antigen test 2 were found positive in 148 (sensitivity 0.664, 95%CI 0.599, 0.722) and 141 (sensitivity 0.623, 95%CI 0.558, 0.684) patients, respectively. When only symptomatic patients were analysed, sensitivity increased to 0.738 (95%CI 0.667, 0.799) for the antigen test 1 and to 0.685 (95%CI 0.611, 0.750) for the antigen test 2. The substantial drop in sensitivity to 12.9% (95%CI 0.067, 0.234) was observed for samples with the PCR threshold cycle above >30. CONCLUSIONS: Low sensitivity of antigen tests leads to the considerable risk of false negativity. It is advisable to implement repeated testing with high enough frequency if the antigen test is used as a frontline screening tool, and to follow with PCR if it is applied to vulnerable populations.