scholarly journals Serologic SARS-CoV-2 testing in healthcare workers with positive RT-PCR test or Covid-19 related symptoms

2020 ◽  
Author(s):  
Giovanni Visci ◽  
Vittorio Lodi ◽  
Roberta Bonfiglioli ◽  
Tiziana Lazzarotto ◽  
Francesco S. Violante ◽  
...  
Keyword(s):  
Healthcare Workers ◽  
Lateral Flow ◽  
Public Hospitals ◽  
Lateral Flow Immunoassay ◽  
Enzyme Linked Immunosorbent Assay ◽  
Limited Information ◽  
Rt Pcr ◽  
Positive Serology ◽  
Serologic Response ◽  
Pcr Test

AbstractBackgroundLimited information is available on prevalence and determinants of serologic response to SARS-CoV-2 infection among healthcare workers (HCWs).MethodsWe analyzed the results of serologic testing with chemiluminescence immunoassay analyzer (CLIA), lateral flow immunoassay (LFIA) and enzyme-linked immunosorbent assay (ELISA) test among 544 HCWs with at least one positive RT-PCR test and 157 HCWs with Covid-19 related symptoms without a positive RT-PCR test from public hospitals in Bologna, Northern Italy. Tests were performed between March and August 2020. We fitted multivariate logistic regression models to identify determinants of positive serology.ResultsThe sensitivity of SARS-CoV-2 was 75.2% (LFIA) and 90.6% (CLIA). No differences in seropositivity were observed by sex, while older HCWs had higher positivity than other groups, and nurses had higher positivity compared to physicians, but not other HCWs. An estimated 73.4% of HCWs with Covid-19 symptoms without RT-PCR test were not infected with SARS-CoV-2.ConclusionsOur study provides the best available data on sensitivity of serologic tests and on determinants of serologic response among HCWs positive for SARS-CoV-2, and provide evidence on the low specificity of Covid-19 related symptoms to identify infected HCWs.SummaryThe sensitivity of SARS-CoV-2 lateral flow immunoassay serology in healthcare workers (HCWs) was 75.2%. Older HCWs and nurses had higher positivity than other groups. An estimated 73.4% of HCWs with Covid-19 symptoms without RT-PCR test were not infected with SARS-CoV-2.

scholarly journals SARS-CoV-2 Seroprevalence in Healthcare Workers of Kaunas Hospitals during the First Wave of the COVID-19 Pandemic

Medicina ◽  
2021 ◽  
Vol 57 (2) ◽  
pp. 148 ◽  
Author(s):  
Laura Pereckaitė ◽  
Asta Dambrauskienė ◽  
Daiva Urbonienė ◽  
Saulius Sadauskas ◽  
Kęstutis Petrikonis ◽  
...  
Keyword(s):  
Healthcare Workers ◽  
Lateral Flow ◽  
Immunoglobulin M ◽  
Lateral Flow Immunoassay ◽  
Enzyme Linked Immunosorbent Assay ◽  
Antibody Testing ◽  
Serum Samples ◽  
Positive Group ◽  
Percent Agreement ◽  
Specific Igg

Background and objective: Serologic testing is a useful additional method for the diagnosis of COVID-19. It is also used for population-based seroepidemiological studies. The objective of the study was to determine SARS-CoV-2 seroprevalence in healthcare workers of Kaunas hospitals and to compare two methods for specific SARS-CoV-2 antibody testing. Materials and Methods: A total of 432 healthcare workers in Kaunas hospitals were enrolled in this study. Each participant filled a questionnaire including questions about their demographics, contact with suspected or confirmed COVID-19, acute respiratory symptoms, and whether they contacted their general practitioner, could not come to work, or had to be hospitalized. Capillary blood was used to test for SARS-CoV-2 specific immunoglobulin G (IgG) and immunoglobulin M (IgM) a lateral flow immunoassay. Serum samples were used to test for specific IgG and IgA class immunoglobulins using semiquantitative enzyme-linked immunosorbent assay (ELISA) method. Results: 24.77% of study participants had direct contact with a suspected or confirmed case of COVID-19. A total of 64.81% of studied individuals had at least one symptom representing acute respiratory infection, compatible with COVID-19. Lateral flow immunoassay detected SARS-CoV-2 specific IgG class immunoglobulins in 1.16% of the tested group. Fever, cough, dyspnea, nausea, diarrhea, headache, conjunctivitis, muscle pain, and loss of smell and taste predominated in the anti-SARS-CoV-2 IgG-positive group. Using ELISA, specific IgG were detected in 1.32% of the tested samples. Diarrhea, loss of appetite, and loss of smell and taste sensations were the most predominant symptoms in anti-SARS-CoV-2 IgG-positive group. The positive percent agreement of the two testing methods was 50%, and negative percent agreement was 99.66%. Conclusions: 1.16% of tested healthcare workers of Kaunas hospitals were anti-SARS-CoV-2 IgG-positive. The negative percent agreement of the lateral flow immunoassay and ELISA exceeded 99%.

scholarly journals Comparative Analysis of the Euroimmun CXCL13 Enzyme-Linked Immunosorbent Assay and the ReaScan Lateral Flow Immunoassay for Diagnosis of Lyme Neuroborreliosis

2020 ◽  
Vol 58 (9) ◽  
Author(s):  
Katharina Ziegler ◽  
Anca Rath ◽  
Christoph Schoerner ◽  
Renate Meyer ◽  
Thomas Bertsch ◽  
...  
Keyword(s):  
Immunosorbent Assay ◽  
Roc Curve ◽  
Point Of Care ◽  
Lateral Flow ◽  
Lyme Neuroborreliosis ◽  
Diagnostic Tools ◽  
Lateral Flow Immunoassay ◽  
Enzyme Linked Immunosorbent Assay ◽  
European Federation ◽  
Point Of Care Test

ABSTRACT Diagnosis of Lyme neuroborreliosis (LNB) is challenging, as long as Borrelia-specific intrathecal antibodies are not yet detectable. The chemokine CXCL13 is elevated in the cerebrospinal fluid (CSF) of LNB patients. Here, we compared the performances of the Euroimmun CXCL13 enzyme-linked immunosorbent assay (CXCL13 ELISA) and the ReaScan CXCL13 lateral flow immunoassay (CXCL13 LFA), a rapid point-of-care test, to support the diagnosis of LNB. In a dual-center case-control study, CSF samples from 90 patients (34 with definite LNB, 10 with possible LNB, and 46 with other central nervous system [CNS] diseases [non-LNB group]) were analyzed with the CXCL13 ELISA and the CXCL13 LFA. Classification of patients followed the European Federation of Neurological Societies (EFNS) guidelines on LNB. The CXCL13 ELISA detected elevated CXCL13 levels in all patients with definite LNB (median, 1,409 pg/ml) compared to the non-LNB controls (median, 20.7 pg/ml; P < 0.0001), with a sensitivity of 100% and a specificity of 84.8% (cutoff value, 78.6 pg/ml; area under the receiver operating characteristic [ROC] curve, 0.93). Similarly, the CXCL13 LFA yielded elevated CXCL13 levels in 31 patients with definite LNB (median arbitrary value, 223.5) compared to the non-LNB control patients (median arbitrary value, 0; P < 0.0001) and had a sensitivity and specificity of 91.2% and 93.5%, respectively (cutoff arbitrary value, 22.5; area under the ROC curve, 0.94). The correlation between the CXCL13 levels obtained by ELISA and LFA was strong (Spearman correlation coefficient r = 0.89; P < 0.0001). The CXCL13 ELISA and the CXCL13 LFA are comparable diagnostic tools for the detection of CXCL13 in the CSF of patients with definite LNB. The advantage of the CXCL13 LFA is the shorter time to result.

scholarly journals First Report of Lolium latent virus in Ryegrass in the United States

Plant Disease ◽  
2006 ◽  
Vol 90 (4) ◽  
pp. 528-528 ◽  
Author(s):  
C. J. Maroon-Lango ◽  
J. Hammond ◽  
S. Warnke ◽  
R. Li ◽  
R. Mock
Keyword(s):  
United States ◽  
Lolium Perenne ◽  
The United States ◽  
Latent Virus ◽  
Hybrid Population ◽  
Enzyme Linked Immunosorbent Assay ◽  
Rt Pcr ◽  
High Sequence Identity ◽  
Lolium Perenne L ◽  
Pcr Test

Initial reports of the presence of Lolium latent virus (LLV) in Lolium perenne L. and L. multiflorum Lam. breeding clones in Germany, the Netherlands, France (2), and recently the United Kingdom (3,4; described as Ryegrass latent virus prior to identification as LLV) prompted us to evaluate clonally propagated Lolium plants from the United States. Four genetically distinct plants (viz., MF22, MF48, MF125, and MF132) that have been maintained clonally for 5 years from a Lolium perenne × L. multiflorum hybrid population established in the United States exhibited either no symptoms or mild chlorotic flecking that coalesced to form chlorotic to necrotic streaking on the leaves. All four clonal plants tested positive using reverse transcription-polymerase chain reaction (RT-PCR) with the Potexvirus group PCR test (Agdia, Inc., Elkhart, IN), whereas all clones but MF48 tested positive using the Potyvirus group PCR test (Agdia, Inc.). No amplicons were obtained when the same plants were tested for tobamovirus, carlavirus, and closterovirus using appropriate virus group-specific primers. Cloning and sequencing of the potexviral amplicons revealed very high sequence identity with the comparable region of LLV-UK (GenBank Accession No. DQ333886), whereas those of the potyviral amplicons (GenBank Accession Nos. DQ355837 and DQ355838) were nearly identical with the comparable region of Ryegrass mosaic virus (RGMV), a rymovirus first reported from the United States in 1957 (1). Using indirect enzyme-linked immunosorbent assay (ELISA), extracts from all four Lolium clonal propagations tested positive for LLV using the antiserum raised to LLV-Germany (courtesy of Dr. Huth), whereas the potyvirus-positive results from RT-PCR of the three clones were confirmed using indirect ELISA with the broad spectrum potyvirus monoclonal antibody, PTY-1. LLV from singly or dually infected Lolium clones was transmitted to Nicotiana benthamiana Domin. but not to N. tabacum L. by mechanical inoculation. LLV was purified from infected N. benthamiana. Similar sized flexuous rods were observed using electron microscopy in leaf dip samples from Lolium clones and aliquots of the virions purified from N. benthamiana. References: (1) G. W. Bruehl et al. Phytopathology 47:517, 1957. (2) W. Huth et al. Agronomie 15:508, 1995. (3) R. Li et al. Asian Conf. Plant Pathol. 2:89, 2005. (4) C. Maroon-Lango et al. Int. Congr. Virol. 13:63, 2005.

Point-Of-Care Clinical Evaluation of the Clungene® SARS-CoV-2 Virus IgG/IgM 15-minute rapid test cassette with the Cobas® Roche RT-PCR platform in patients with or without Covid-19

2021 ◽  
Author(s):  
Fadi Haddad ◽  
Christopher C Lamb ◽  
Ravina Kullar ◽  
George Sakoulas
Keyword(s):  
Symptom Onset ◽  
Serological Test ◽  
Point Of Care ◽  
Diagnostic Testing ◽  
Rapid Test ◽  
Lateral Flow ◽  
Added Value ◽  
Lateral Flow Immunoassay ◽  
Rt Pcr ◽  
Past Infection

Background: Covid-19 remains a pandemic with multiple challenges to confirm patient infectivity: lack of sufficient tests, accurate results, validated quality, and timeliness of results. We hypothesize that a rapid 15-minute Point-Of-Care serological test to evaluate past infection complements diagnostic testing for Covid-19 and significantly enhances testing availability. Method: A three arm observational study at Sharp Healthcare, San Diego, California was conducted using the Clungene® lateral flow immunoassay (LFI) and compared with the Cobas® Roche RT PCR results. Arm 1: Thirty-five (35) subjects with confirmed Covid-19 using RT-PCR were tested twice: prior to 14 days following symptom onset and once between 12 and 70 days. Arm 2: Thirty (30) subjects with confirmed Covid-19 using RT-PCR were tested 12-70 days post symptom onset. Arm 3: Thirty (30) subjects with a negative RT-PCR for Covid-19 were tested 1-10 days following the RT-PCR test date. Results: Specificity of confirmed negative Covid-19 by RT-PCR was 100% (95% CI, 88.4%-100.0%); meaning there was 100% negative positive agreement between the RT-PCR and the Clungene® serological test results. Covid-19 subjects tested prior to day 7 symptom onset were antibody negative. In subjects 7-12 days following symptom onset with a confirmed positive Covid-19 by RT-PCR, the combined sensitivity of IgM and IgG was 58.6% (95% CI, 38.9%-76.5%). In subjects 13-70 days following symptom onset with a confirmed positive Covid-19 by RT-PCR the combined sensitivity of IgM and IgG was 90.5% (95% CI, 80.4%-96.4%). Conclusion: The Clungene® lateral flow immunoassay (LFI) is a useful tool to confirm individuals with an adaptive immune response to SARS-CoV-2 indicating past infection. Providing Point-Of-Care results within 15 minutes without any laboratory instrumentation or specialized software has an added value of increasing test availability to patients who have been symptomatic for more than one week to confirm past infection. Performance characteristics are optimal after 13 days with a sensitivity and specificity of 90% and 100%, respectively.

scholarly journals Development of a multiplex and sensitive lateral flow immunoassay for the diagnosis of periprosthetic joint infection

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Tsung-Ting Tsai ◽  
Tse-Hao Huang ◽  
Natalie Yi-Ju Ho ◽  
Yu-Pei Chen ◽  
Chung-An Chen ◽  
...  
Keyword(s):  
Synovial Fluid ◽  
Clinical Diagnosis ◽  
Periprosthetic Joint Infection ◽  
Diagnostic Tests ◽  
Joint Infection ◽  
Lateral Flow ◽  
Rapid Response ◽  
Detection Sensitivity ◽  
Lateral Flow Immunoassay ◽  
Enzyme Linked Immunosorbent Assay

Abstract The diagnosis of periprosthetic joint infection (PJI) remains a challenge. However, recent studies showed that synovial fluid biomarkers have demonstrated greater diagnostic accuracy than the currently used PJI diagnostic tests. In many diagnostic tests, combining several biomarkers into panels is critical for improving diagnostic efficiency, enhancing the diagnostic precision for specific diseases, and reducing cost. In this study, we prove that combining alpha-defensin and C-reactive protein (CRP) as biomarkers possesses the potential to provide accurate PJI diagnosis. To further verify the result, we developed a multi-target lateral flow immunoassay strip (msLFIA) with staking pad design to obtain on-site rapid response for clinical diagnosis of PJI. A total of 10 synovial fluid samples were tested using the msLFIA, and the results showed that the combined measurements of synovial fluid alpha-defensin and CRP levels were consistent with those obtained from a commercial enzyme-linked immunosorbent assay kit. In addition, we developed a multi-target lateral flow immunoassay strip (msLFIA) with staking pad design to obtain on-site rapid response for clinical diagnosis of PJI, which the multi-target design is used to increase specificity and the stacking pad design is to enhance detection sensitivity. As a result, the turnaround time of the highly sensitive test can be limited from several hours to 20 min. We expect that the developed msLFIA possesses the potential for routine monitoring of PJI as a convenient, low-cost, rapid and easy to use detection device for PJI.

scholarly journals Diagnostic accuracy estimates for COVID-19 RT-PCR and Lateral flow immunoassay tests with Bayesian latent class models

2020 ◽  
Author(s):  
Polychronis Kostoulas ◽  
Paolo Eusebi ◽  
Sonja Hartnack
Keyword(s):  
Diagnostic Accuracy ◽  
Symptom Onset ◽  
Latent Class ◽  
Reference Method ◽  
Latent Class Models ◽  
Lateral Flow ◽  
Lateral Flow Immunoassay ◽  
Rt Pcr ◽  
The Cross ◽  
Class Models

Abstract The objective of this work was to estimate the diagnostic accuracy of RT-PCR and Lateral flow immunoassay tests (LFIA) for COVID-19, depending on the time post symptom onset. Based on the cross-classified results of RT-PCR and LFIA, we used Bayesian latent class models (BLCMs), which do not require a gold standard for the evaluation of diagnostics. Data were extracted from studies that evaluated LFIA (IgG and/or IgM) assays using RT-PCR as the reference method. The cross-classified results of LFIA and RT-PCR were analysed separately for the first, second and third week post symptom onset. The SeRT-PCR was 0.695 (95% probability intervals: 0.563; 0.837) for the first week and remained similar for the second and the third week. The SeIgG/M was 0.318 (0.229; 0.416) for the first week and increased steadily. It was 0.755 (0.673; 0.829) and 0.927 (0.881; 0.965) for the second and third week, respectively. Both tests had a high to absolute Sp, with point median estimates for SpRT-PCR being consistently higher. SpRT-PCR was 0.990 (0.980; 0.998) for the first week. The corresponding value for SpIgG/M was 0.962 (0.905; 0.998). Further, Sp estimates for each test did not differ between weeks. BLCMs provide a valid and efficient alternative for evaluating the rapidly evolving diagnostics for COVID-19, under various clinical settings and for different risk profiles.

scholarly journals Antibodies to SARS-CoV2 detectable for less than 50 days in polymerase chain reaction confirmed COVID-19 patients

2020 ◽  
Vol 7 (9) ◽  
pp. 3378
Author(s):  
Nishant Kumar ◽  
Shibal Bhartiya ◽  
Tarundeep Singh
Keyword(s):  
Polymerase Chain Reaction ◽  
Healthcare Workers ◽  
Health Workers ◽  
Natural Infection ◽  
Rt Pcr ◽  
Chain Reaction ◽  
Cross Sectional Survey ◽  
Polymerase Chain ◽  
Roche Diagnostics ◽  
Pcr Test

Background: A seroprevalence study for COVID-19 antibodies was conducted amongst health workers in Mumbai, India, in June 2020.Methods: Healthcare workers (n=801) underwent a cross sectional survey through electrochemiluminescence immunoassay (Roche diagnostics’ Elecsys anti-SARS-CoV-2 assay, Roche diagnostics, Rotkreuz, Switzerland).Results: Of the 801 healthcare workers, 62 who had been previously diagnosed with a real time-polymerase chain reaction (RT-PCR) proven SARS-CoV-2 infection, 45 (73.6%) were found to be seronegative during the study. The duration between the positive RT-PCR test and the serological testing ranged from 15 to 49 days for 34 (54.8%), and was >50 days in 28 subjects. Up to 28 days after a positive PCR test, 90% of the subjects were found to be seropositive, but this reduced to less than half over the next two weeks (38.5% between 29 and 42 days).Conclusions: Our findings are in agreement with previous reports that demonstrate a peak antibody formation after 3 weeks, and also an early antibody decay that is almost exponential. This may also have a significant effect on the protection vaccines are able to provide considering that a natural infection has such a transient antibody response. 

scholarly journals Clinical Evaluation of a COVID-19 Antibody Lateral Flow Assay using Point of Care Samples

2020 ◽  
Author(s):  
Won Lee ◽  
Steven Straube ◽  
Ryan Sincic ◽  
Jeanne A. Noble ◽  
Juan Carlos Montoy ◽  
...  
Keyword(s):  
Predictive Value ◽  
Point Of Care ◽  
Acute Infection ◽  
High Specificity ◽  
Lateral Flow ◽  
Lateral Flow Immunoassay ◽  
Onset Date ◽  
Rt Pcr ◽  
Serum Samples ◽  
Antibody Positivity

ABSTRACTIntroductionThe ongoing SARS-CoV-2 pandemic has spurred the development of numerous point of care (PoC) immunoassays. Assessments of performance of available kits are necessary to determine their clinical utility. Previous studies have mostly performed these assessments in a laboratory setting, which raises concerns of translating findings for PoC use. The aim of this study was to assess the performance of a lateral flow immunoassay for the detection of SARS-CoV-2 antibodies using samples collected at PoC.MethodOne lateral flow immunoassay (Humasis® COVID-19 IgG/IgM) was tested. In total, 50 PCR RT-PCR positive and 52 RT-PCR negative samples were collected at PoC. Fifty serum specimens from Dec 2018 to Feb 2019 were used as controls for specificity. Serum samples collected between Dec 2019 to Feb 2020 were used as additional comparators. Clinical data including symptom onset date was collected from patient history and the medical record.ResultsThe overall sensitivity for the kit was 74% (95% CI: 59.7% -85.4%). The sensitivity for IgM and IgG detection >14 days after date of onset was 88% (95% CI: 68.8% -97.5%) and 84% (95% CI: 63.9% – 95.5%), with a negative predictive value (NPV) of 94% for IgM (95% CI: 83.5% - 98.8%) and 93% for IgG (95% CI: 81.8% - 97.9%). The overall specificity was 94% (95% CI: 83.5% - 98.8%). The Immunoglobulin specific specificity was 94% for IgM (95% CI: 83.5% - 98.8%) and 98% for IgG (95% CI: 89.4% - 100.0%), with a positive predictive value (PPV) of 88% for IgM (95% CI: 68.8% - 97.5%) and 95% for IgG (95% CI: 77.2% - 99.9%) respectively for samples collected from patients >14 days after date of onset. Specimen collected during early phase of COVID-19 pandemic (Dec 2019 to Feb 2020) showed 11.8% antibody positivity, and 11.3% of PCR-negative patients demonstrated antibody positivity.DiscussionHumasis® COVID-19 IgG/IgM LFA demonstrates greater than 90% PPV and NPV for samples collected 14 days after the onset of symptoms using samples collected at PoC. While not practical for the diagnosis of acute infection, the use of the lateral flow assays with high specificity may have utility for determining seroprevalence or seroconversion in longitudinal studies.

scholarly journals Diagnostic accuracy of an app-guided, self-administered test for influenza among individuals presenting to general practice with influenza-like illness: study protocol

BMJ Open ◽  
2020 ◽  
Vol 10 (11) ◽  
pp. e036298
Author(s):  
Victoria Lyon ◽  
Monica Zigman Suchsland ◽  
Monique Chilver ◽  
Nigel Stocks ◽  
Barry Lutz ◽  
...  
Keyword(s):  
Influenza A ◽  
Test Strip ◽  
Lateral Flow ◽  
Research Network ◽  
Lateral Flow Immunoassay ◽  
Rt Pcr ◽  
Test Procedures ◽  
Influenza Like Illness ◽  
Test Kit ◽  
Test Strip Reader

IntroductionDiagnostic tests for influenza in Australia are currently only authorised for use in clinical settings. At-home diagnostic testing for influenza could reduce the need for patient contact with healthcare services, which potentially could contribute to symptomatic improvement and reduced spread of influenza. We aim to determine the accuracy of an app-guided nasal self-swab combined with a lateral flow immunoassay for influenza conducted by individuals with influenza-like illness (ILI).Methods and analysisAdults (≥18 years) presenting with ILI will be recruited by general practitioners (GP) participating in Australian Sentinel Practices Research Network. Eligible participants will have a nasal swab obtained by their GP for verification of influenza A/B status using reverse transcription polymerase chain reaction (RT-PCR) test at an accredited laboratory. Participants will receive an influenza test kit and will download an app that collects self-reported symptoms and influenza risk factors, then instructs them in obtaining a low-nasal self-swab, running a QuickVue influenza A+B lateral flow immunoassay (Quidel Corporation) and interpreting the results. Participants will also interpret an enhanced image of the test strip in the app. The primary outcome will be the accuracy of participants’ test interpretation compared with the laboratory RT-PCR reference standard. Secondary analyses will include accuracy of the enhanced test strip image, accuracy of an automatic test strip reader algorithm and validation of prediction rules for influenza based on self-reported symptoms. A post-test survey will be used to obtain participant feedback on self-test procedures.Ethics and disseminationThe study was approved by the Human Research and Ethic Committee (HREC) at the University of Adelaide (H-2019-116). Protocol details and any amendments will be reported to https://www.tga.gov.au/. Results will be published in the peer-reviewed literature, and shared with stakeholders in the primary care and diagnostics communities.Trial registration numberAustralia New Zealand Clinical Trial Registry (U1111-1237-0688).

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