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1.
J Med Virol ; 94(6): 2460-2470, 2022 06.
Article in English | MEDLINE | ID: covidwho-1748622

ABSTRACT

Coronavirus Disease 2019 (COVID-19) serology has an evolving role in the diagnosis of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection. However, its use in hospitalized patients with acute respiratory symptoms remains unclear. Hospitalized patients with acute respiratory illness admitted to an isolation ward were recruited. All patients had negative nasopharyngeal swab polymerase chain reaction (PCR) for SARS-CoV-2. Serological studies using four separate assays (cPass: surrogate neutralizing enzyme-linked immunosorbent assay [ELISA]; Elecsys: N-antigen based chemiluminescent assay; SFB: S protein flow-based; epitope peptide-based ELISA) were performed on stored plasma collected from patients during the initial hospital stay, and a convalescent visit 4-12 weeks later. Of the 51 patients studied (aged 54, interquartile range 21-84; 62.7% male), no patients tested positive on the Elecsys or cPass assays. Out of 51 patients, 5 had antibodies detected on B-cell Epitope Assay and 3/51 had antibodies detected on SFB assay. These 8 patients with positive serological test to COVID-19 were more likely to have a high-risk occupation (p = 0.039), bacterial infection (p = 0.028), and neutrophilia (p = 0.013) during their initial hospital admission. Discrepant COVID-19 serological findings were observed among those with recent hospital admissions and bacterial infections. The positive serological findings within our cohort raise important questions about the interpretation of sero-epidemiology during the current pandemic.


Subject(s)
COVID-19 , SARS-CoV-2 , Antibodies, Viral , COVID-19/diagnosis , Enzyme-Linked Immunosorbent Assay , Female , Fever , Humans , Male , Pandemics , Polymerase Chain Reaction , SARS-CoV-2/genetics
3.
Brain Behav Immun Health ; 19: 100406, 2022 Feb.
Article in English | MEDLINE | ID: covidwho-1592211

ABSTRACT

The COVID-19 pandemic has had an unprecedented impact on healthcare systems globally, giving rise to significant morbidity and mortality. Vaccination has been widely regarded as the most important strategy to contain the pandemic. Whilst local side-effects of the BNT-162b2 (Pfizer-BioNTech) vaccine are well known, concern has emerged due to sporadic reports of immune-mediated adverse effects (Cines and Bussel, 2021; Rela et al., 2021). As of August 19, 2021, 4.54 million individuals had received COVID-19 vaccines in Singapore (Oxford Martin School UoO, 2021). We report a case series of two patients who developed aseptic meningitis after vaccination.

4.
J Clin Immunol ; 42(2): 214-229, 2022 02.
Article in English | MEDLINE | ID: covidwho-1544509

ABSTRACT

The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) variants of concern (VOCs) that have become dominant as the pandemic progresses bear the ORF8 mutation together with multiple spike mutations. A 382-nucleotide deletion (Δ382) in the ORF7b and ORF8 regions has been associated with milder disease phenotype and less systemic inflammation in COVID-19 patients. However, its impact on host immunity against SARS-CoV-2 remains undefined. Here, RNA-sequencing was performed to elucidate whole blood transcriptomic profiles and identify contrasting immune signatures between patients infected with either wildtype or Δ382 SARS-CoV-2 variant. Interestingly, the immune landscape of Δ382 SARS-CoV-2 infected patients featured an increased adaptive immune response, evidenced by enrichment of genes related to T cell functionality, a more robust SARS-CoV-2-specific T cell immunity, as well as a more rapid antibody response. At the molecular level, eukaryotic initiation factor 2 signaling was found to be upregulated in patients bearing Δ382, and its associated genes were correlated with systemic levels of T cell-associated and pro-inflammatory cytokines. This study provides more in-depth insight into the host-pathogen interactions of ORF8 with great promise as a therapeutic target to combat SARS-CoV-2 infection.


Subject(s)
Adaptive Immunity/immunology , COVID-19/immunology , SARS-CoV-2/immunology , Cytokines/immunology , Host-Pathogen Interactions/immunology , Humans , Inflammation/immunology , Mutation/immunology , Pandemics/prevention & control , T-Lymphocytes/immunology
7.
Indoor Air ; n/a(n/a), 2021.
Article in English | Wiley | ID: covidwho-1409407

ABSTRACT

Abstract Reliable methods to detect the presence of SARS-CoV-2 at venues where people gather are essential for epidemiological surveillance to guide public policy. Communal screening of air in a highly crowded space has the potential to provide early warning on the presence and potential transmission of SARS-CoV-2 as suggested by studies early in the epidemic. As hospitals and public facilities apply varying degrees of restrictions and regulations, it is important to provide multiple methodological options to enable environmental SARS-CoV-2 surveillance under different conditions. This study assessed the feasibility of using high-flowrate air samplers combined with RNA extraction kit designed for environmental sample to perform airborne SARS-CoV-2 surveillance in hospital setting, tested by RT-qPCR. The success rate of the air samples in detecting SARS-CoV-2 was then compared with surface swab samples collected in the same proximity. Additionally, positive RT-qPCR samples underwent viral culture to assess the viability of the sampled SARS-CoV-2. The study was performed in inpatient ward environments of a quaternary care university teaching hospital in Singapore housing active COVID-19 patients within the period of February to May 2020. Two types of wards were tested, naturally ventilated open-cohort ward and mechanically ventilated isolation ward. Distances between the site of air sampling and the patient cluster in the investigated wards were also recorded. No successful detection of airborne SARS-CoV-2 was recorded when 50 L/min air samplers were used. Upon increasing the sampling flowrate to 150 L/min, our results showed a high success rate in detecting the presence of SARS-CoV-2 from the air samples (72%) compared to the surface swab samples (9.6%). The positive detection rate of the air samples along with the corresponding viral load could be associated with the distance between sampling site and patient. The furthest distance from patient with PCR-positive air samples was 5.5 m. The airborne SARS-CoV-2 detection was comparable between the two types of wards with 60%?87.5% success rate. High prevalence of the virus was found in toilet areas, both on surfaces and in air. Finally, no successful culture attempt was recorded from the environmental air or surface samples.

8.
Biosens Bioelectron ; 194: 113629, 2021 Dec 15.
Article in English | MEDLINE | ID: covidwho-1401251

ABSTRACT

Accurate and accessible nucleic acid diagnostics is critical to reducing the spread of COVID-19 and resuming socioeconomic activities. Here, we present an integrated platform for the direct detection of SARS-CoV-2 RNA targets near patients. Termed electrochemical system integrating reconfigurable enzyme-DNA nanostructures (eSIREN), the technology leverages responsive molecular nanostructures and automated microfluidics to seamlessly transduce target-induced molecular activation into an enhanced electrochemical signal. Through responsive enzyme-DNA nanostructures, the technology establishes a molecular circuitry that directly recognizes specific RNA targets and catalytically enhances signaling; only upon target hybridization, the molecular nanostructures activate to liberate strong enzymatic activity and initiate cascading reactions. Through automated microfluidics, the system coordinates and interfaces the molecular circuitry with embedded electronics; its pressure actuation and liquid-guiding structures improve not only analytical performance but also automated implementation. The developed platform establishes a detection limit of 7 copies of RNA target per µl, operates against the complex biological background of native patient samples, and is completed in <20 min at room temperature. When clinically evaluated, the technology demonstrates accurate detection in extracted RNA samples and direct swab lysates to diagnose COVID-19 patients.


Subject(s)
Biosensing Techniques , COVID-19 , Nanostructures , Humans , Microfluidics , RNA, Viral/genetics , SARS-CoV-2
10.
Adv Sci (Weinh) ; 8(18): e2101155, 2021 09.
Article in English | MEDLINE | ID: covidwho-1316191

ABSTRACT

Accessible and adaptable nucleic acid diagnostics remains a critical challenge in managing the evolving COVID-19 pandemic. Here, an integrated molecular nanotechnology that enables direct and programmable detection of SARS-CoV-2 RNA targets in native patient specimens is reported. Termed synergistic coupling of responsive equilibrium in enzymatic network (SCREEN), the technology leverages tunable, catalytic molecular nanostructures to establish an interconnected, collaborative architecture. SCREEN mimics the extraordinary organization and functionality of cellular signaling cascades. Through programmable enzyme-DNA nanostructures, SCREEN activates upon interaction with different RNA targets to initiate multi-enzyme catalysis; through system-wide favorable equilibrium shifting, SCREEN directly transduces a single target binding into an amplified electrical signal. To establish collaborative equilibrium coupling in the architecture, a computational model that simulates all reactions to predict overall performance and optimize assay configuration is developed. The developed platform achieves direct and sensitive RNA detection (approaching single-copy detection), fast response (assay reaction is completed within 30 min at room temperature), and robust programmability (across different genetic loci of SARS-CoV-2). When clinically evaluated, the technology demonstrates robust and direct detection in clinical swab lysates to accurately diagnose COVID-19 patients.


Subject(s)
COVID-19/virology , DNA, Catalytic/genetics , Nanostructures/chemistry , SARS-CoV-2/genetics , Humans , Limit of Detection , Molecular Diagnostic Techniques/methods , Nanotechnology/methods , Pandemics/prevention & control , RNA, Viral/genetics , Specimen Handling/methods
11.
Front Immunol ; 12: 680188, 2021.
Article in English | MEDLINE | ID: covidwho-1311374

ABSTRACT

A significant proportion of COVID-19 patients will progress to critical illness requiring invasive mechanical ventilation. This accentuates the need for a therapy that can reduce the severity of COVID-19. Clinical trials have shown the effectiveness of remdesivir in shortening recovery time and decreasing progression to respiratory failure and mechanical ventilation. However, some studies have highlighted its lack of efficacy in patients on high-flow oxygen and mechanical ventilation. This study uncovers some underlying immune response differences between responders and non-responders to remdesivir treatment. Immunological analyses revealed an upregulation of tissue repair factors BDNF, PDGF-BB and PIGF-1, as well as an increase in ratio of Th2-associated cytokine IL-4 to Th1-associated cytokine IFN-γ. Serological profiling of IgG subclasses corroborated this observation, with significantly higher magnitude of increase in Th2-associated IgG2 and IgG4 responses. These findings help to identify the mechanisms of immune regulation accompanying successful remdesivir treatment in severe COVID-19 patients.


Subject(s)
Adenosine Monophosphate/analogs & derivatives , Alanine/analogs & derivatives , Antiviral Agents/therapeutic use , COVID-19/drug therapy , Cytokines/blood , Hospitalization , SARS-CoV-2/genetics , Adenosine Monophosphate/therapeutic use , Adult , Aged , Alanine/therapeutic use , Antibodies, Viral/blood , Antibodies, Viral/immunology , Becaplermin/blood , Brain-Derived Neurotrophic Factor/blood , COVID-19/blood , COVID-19/immunology , Case-Control Studies , Female , Humans , Immunoglobulin G/blood , Immunoglobulin G/immunology , Male , Membrane Proteins/blood , Middle Aged , Prospective Studies , Spike Glycoprotein, Coronavirus/immunology , Treatment Outcome
12.
EBioMedicine ; 66: 103319, 2021 Apr.
Article in English | MEDLINE | ID: covidwho-1174196

ABSTRACT

BACKGROUND: Host determinants of severe coronavirus disease 2019 include advanced age, comorbidities and male sex. Virologic factors may also be important in determining clinical outcome and transmission rates, but limited patient-level data is available. METHODS: We conducted an observational cohort study at seven public hospitals in Singapore. Clinical and laboratory data were collected and compared between individuals infected with different SARS-CoV-2 clades. Firth's logistic regression was used to examine the association between SARS-CoV-2 clade and development of hypoxia, and quasi-Poisson regression to compare transmission rates. Plasma samples were tested for immune mediator levels and the kinetics of viral replication in cell culture were compared. FINDINGS: 319 patients with PCR-confirmed SARS-CoV-2 infection had clinical and virologic data available for analysis. 29 (9%) were infected with clade S, 90 (28%) with clade L/V, 96 (30%) with clade G (containing D614G variant), and 104 (33%) with other clades 'O' were assigned to lineage B.6. After adjusting for age and other covariates, infections with clade S (adjusted odds ratio (aOR) 0·030 (95% confidence intervals (CI): 0·0002-0·29)) or clade O (B·6) (aOR 0·26 (95% CI 0·064-0·93)) were associated with lower odds of developing hypoxia requiring supplemental oxygen compared with clade L/V. Patients infected with clade L/V had more pronounced systemic inflammation with higher concentrations of pro-inflammatory cytokines, chemokines and growth factors. No significant difference in the severity of clade G infections was observed (aOR 0·95 (95% CI: 0·35-2·52). Though viral loads were significantly higher, there was no evidence of increased transmissibility of clade G, and replicative fitness in cell culture was similar for all clades. INTERPRETATION: Infection with clades L/V was associated with increased severity and more systemic release of pro-inflammatory cytokines. Infection with clade G was not associated with changes in severity, and despite higher viral loads there was no evidence of increased transmissibility.


Subject(s)
COVID-19/etiology , COVID-19/transmission , SARS-CoV-2/genetics , SARS-CoV-2/pathogenicity , Adult , Age Factors , Aged , COVID-19/epidemiology , COVID-19/immunology , Comorbidity , Female , Humans , Hypoxia/therapy , Hypoxia/virology , Male , Middle Aged , Singapore/epidemiology , Viral Load
13.
Elife ; 102021 03 23.
Article in English | MEDLINE | ID: covidwho-1146275

ABSTRACT

Numerous reports of vascular events after an initial recovery from COVID-19 form our impetus to investigate the impact of COVID-19 on vascular health of recovered patients. We found elevated levels of circulating endothelial cells (CECs), a biomarker of vascular injury, in COVID-19 convalescents compared to healthy controls. In particular, those with pre-existing conditions (e.g., hypertension, diabetes) had more pronounced endothelial activation hallmarks than non-COVID-19 patients with matched cardiovascular risk. Several proinflammatory and activated T lymphocyte-associated cytokines sustained from acute infection to recovery phase, which correlated positively with CEC measures, implicating cytokine-driven endothelial dysfunction. Notably, we found higher frequency of effector T cells in our COVID-19 convalescents compared to healthy controls. The activation markers detected on CECs mapped to counter receptors found primarily on cytotoxic CD8+ T cells, raising the possibility of cytotoxic effector cells targeting activated endothelial cells. Clinical trials in preventive therapy for post-COVID-19 vascular complications may be needed.


Subject(s)
COVID-19/complications , Cardiovascular Diseases/etiology , Endothelium, Vascular/pathology , Lymphocyte Activation , Adult , Aged , COVID-19/immunology , COVID-19/pathology , Cardiovascular Diseases/immunology , Cardiovascular Diseases/pathology , Cytokines/immunology , Endothelial Cells/immunology , Endothelial Cells/pathology , Endothelium, Vascular/immunology , Female , Humans , Male , Middle Aged , Risk Factors
14.
Sci Adv ; 7(12)2021 03.
Article in English | MEDLINE | ID: covidwho-1140315

ABSTRACT

Despite the importance of nucleic acid testing in managing the COVID-19 pandemic, current detection approaches remain limited due to their high complexity and extensive processing. Here, we describe a molecular nanotechnology that enables direct and sensitive detection of viral RNA targets in native clinical samples. The technology, termed catalytic amplification by transition-state molecular switch (CATCH), leverages DNA-enzyme hybrid complexes to form a molecular switch. By ratiometric tuning of its constituents, the multicomponent molecular switch is prepared in a hyperresponsive state-the transition state-that can be readily activated upon the binding of sparse RNA targets to turn on substantial enzymatic activity. CATCH thus achieves superior performance (~8 RNA copies/µl), direct fluorescence detection that bypasses all steps of PCR (<1 hour at room temperature), and versatile implementation (high-throughput 96-well format and portable microfluidic assay). When applied for clinical COVID-19 diagnostics, CATCH demonstrated direct and accurate detection in minimally processed patient swab samples.


Subject(s)
COVID-19 Nucleic Acid Testing , COVID-19 , Lab-On-A-Chip Devices , Microfluidic Analytical Techniques , Point-of-Care Testing , SARS-CoV-2/genetics , COVID-19/diagnosis , COVID-19/genetics , COVID-19 Nucleic Acid Testing/instrumentation , COVID-19 Nucleic Acid Testing/methods , Humans , Limit of Detection
15.
Cell Rep Med ; 2(2): 100193, 2021 02 16.
Article in English | MEDLINE | ID: covidwho-1069040

ABSTRACT

Early detection of infection is crucial to limit the spread of coronavirus disease 2019 (COVID-19). Here we develop a flow cytometry-based assay to detect severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) spike (S) protein antibodies in individuals with COVID-19. The assay detects specific immunoglobulin M (IgM), IgA, and IgG in individuals with COVID-19 and also acquisition of all IgG subclasses, with IgG1 being the most dominant. The antibody response is significantly higher at a later stage of infection. Furthermore, asymptomatic individuals with COVID-19 also develop specific IgM, IgA, and IgG, with IgG1 being the most dominant subclass. Although the antibody levels are lower in asymptomatic infection, the assay is highly sensitive and detects 97% of asymptomatic infections. These findings demonstrate that the assay can be used for serological analysis of symptomatic and asymptomatic infections, which may otherwise remain undetected.


Subject(s)
Antibodies, Viral/blood , COVID-19/pathology , Immunoglobulin Class Switching/physiology , Immunoglobulin G/blood , SARS-CoV-2/metabolism , Spike Glycoprotein, Coronavirus/immunology , Antibodies, Viral/immunology , Asymptomatic Diseases , COVID-19/immunology , COVID-19/virology , Flow Cytometry , Humans , Immunoglobulin G/immunology , Immunologic Tests/methods , SARS-CoV-2/isolation & purification
16.
J Infect ; 82(4): e27-e28, 2021 04.
Article in English | MEDLINE | ID: covidwho-988400
18.
PLoS One ; 15(5): e0232168, 2020.
Article in English | MEDLINE | ID: covidwho-832041

ABSTRACT

BACKGROUND: Healthcare workers (HCWs) and non-HCWs may contribute to the transmission of influenza-like illness (ILI) to colleagues and susceptible patients by working while sick (presenteeism). The present study aimed to explore the views and behavior of HCWs and non-HCWs towards the phenomenon of working while experiencing ILI. METHODS: The study was a cross-sectional online survey conducted between October 2018 and January 2019 to explore sickness presenteeism and the behaviour of HCWs and non-HCWs when experiencing ILI. The survey questionnaire was distributed to the members and international networks of the International Society of Antimicrobial Chemotherapy (ISAC) Infection Prevention and Control (IPC) Working Group, as well as via social media platforms, including LinkedIn, Twitter and IPC Blog. RESULTS: In total, 533 respondents from 49 countries participated (Europe 69.2%, Asia-Pacific 19.1%, the Americas 10.9%, and Africa 0.8%) representing 249 HCWs (46.7%) and 284 non-HCWs (53.2%). Overall, 312 (58.5%; 95% confidence interval [CI], 56.2-64.6) would continue to work when sick with ILI, with no variation between the two categories. Sixty-seven (26.9%) HCWs and forty-six (16.2%) non-HCWs would work with fever alone (p<0 .01) Most HCWs (89.2-99.2%) and non-HCWs (80%-96.5%) would work with "minor" ILI symptoms, such as sore throat, sinus cold, fatigue, sneezing, runny nose, mild cough and reduced appetite. CONCLUSION: A future strategy to successfully prevent the transmission of ILI in healthcare settings should address sick-leave policy management, in addition to encouraging the uptake of influenza vaccine.


Subject(s)
Emotions , Health Personnel/psychology , Influenza, Human , Internationality , Surveys and Questionnaires , Adolescent , Adult , Female , Health Personnel/statistics & numerical data , Humans , Male , Middle Aged , Presenteeism/statistics & numerical data , Young Adult
20.
EBioMedicine ; 58: 102911, 2020 Aug.
Article in English | MEDLINE | ID: covidwho-662643

ABSTRACT

BACKGROUND: Given the unceasing worldwide surge in COVID-19 cases, there is an imperative need to develop highly specific and sensitive serology assays to define exposure to Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2). METHODS: Pooled plasma samples from PCR positive COVID-19 patients were used to identify linear B-cell epitopes from a SARS-CoV-2 peptide library of spike (S), envelope (E), membrane (M), and nucleocapsid (N) structural proteins by peptide-based ELISA. Hit epitopes were further validated with 79 COVID-19 patients with different disease severity status, 13 seasonal human CoV, 20 recovered SARS patients and 22 healthy donors. FINDINGS: Four immunodominant epitopes, S14P5, S20P2, S21P2 and N4P5, were identified on the S and N viral proteins. IgG responses to all identified epitopes displayed a strong detection profile, with N4P5 achieving the highest level of specificity (100%) and sensitivity (>96%) against SARS-CoV-2. Furthermore, the magnitude of IgG responses to S14P5, S21P2 and N4P5 were strongly associated with disease severity. INTERPRETATION: IgG responses to the peptide epitopes can serve as useful indicators for the degree of immunopathology in COVID-19 patients, and function as higly specific and sensitive sero-immunosurveillance tools for recent or past SARS-CoV-2 infections. The flexibility of these epitopes to be used alone or in combination will allow for the development of improved point-of-care-tests (POCTs). FUNDING: Biomedical Research Council (BMRC), the A*ccelerate GAP-funded project (ACCL/19-GAP064-R20H-H) from Agency of Science, Technology and Research (A*STAR), and National Medical Research Council (NMRC) COVID-19 Research fund (COVID19RF-001) and CCGSFPOR20002. ATR is supported by the Singapore International Graduate Award (SINGA), A*STAR.


Subject(s)
B-Lymphocytes/immunology , Coronavirus Infections/diagnosis , Epitopes/immunology , Nucleocapsid Proteins/immunology , Pneumonia, Viral/diagnosis , Spike Glycoprotein, Coronavirus/immunology , Adult , Biomarkers/blood , COVID-19 , Coronavirus Infections/blood , Coronavirus Infections/immunology , Epitopes/blood , Female , Humans , Male , Middle Aged , Pandemics , Pneumonia, Viral/blood , Pneumonia, Viral/immunology , Serologic Tests/methods
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