ABSTRACT
Many tour providers have pinned their hopes on providing virtual tours to bring back visitors in the ongoing coronavirus disease 2019 (COVID-19) pandemic. In this paper, we develop an analytical model to examine whether free virtual tours can help attract more visitors. We consider a tour provider deciding whether to provide a free virtual tour and its grade if any is provided to maximize visitors' physical presence. Potential visitors possess heterogeneous preferences and perceived equivalence, and the tour provider knows only their respective random distributions. The model is solved to maximize tour providers' physical demand. Our analysis finds that a free virtual tour can help if potential visitors significantly underestimate the physical tour and identifies the critical threshold;we also find that the COVID-19 pandemic reduces the likelihood that a free virtual tour can help. This paper contributes to the tourism management community by accentuating the dark side of virtual tours, suggesting that tour providers should be prudent before introducing any virtual tour. We also provide guidelines for virtual tourism, helping tour providers respond to and recover from the COVID-19 pandemic and other uncertain situations.
ABSTRACT
Many tour providers have pinned their hopes on providing virtual tours to bring back visitors in the ongoing coronavirus disease 2019 (COVID-19) pandemic. In this paper, we develop an analytical model to examine whether free virtual tours can help attract more visitors. We consider a tour provider deciding whether to provide a free virtual tour and its grade if any is provided to maximize visitors’ physical presence. Potential visitors possess heterogeneous preferences and perceived equivalence, and the tour provider knows only their respective random distributions. The model is solved to maximize tour providers’ physical demand. Our analysis finds that a free virtual tour can help if potential visitors significantly underestimate the physical tour and identifies the critical threshold;we also find that the COVID-19 pandemic reduces the likelihood that a free virtual tour can help. This paper contributes to the tourism management community by accentuating the dark side of virtual tours, suggesting that tour providers should be prudent before introducing any virtual tour. We also provide guidelines for virtual tourism, helping tour providers respond to and recover from the COVID-19 pandemic and other uncertain situations.
ABSTRACT
BACKGROUND: Elucidation of the molecular mechanisms involved in the pathogenesis of coronavirus disease 2019 (COVID-19) may help to discover therapeutic targets. METHODS: To determine the metabolomic profile of circulating plasma from COVID-19 survivors with pulmonary sequelae 3 months after discharge, a random, outcome-stratified case-control sample was analyzed. We enrolled 103 recovered COVID-19 patients as well as 27 healthy donors, and performed pulmonary function tests, computerized tomography (CT) scans, laboratory examinations, and liquid chromatography-mass spectrometry. RESULTS: Plasma metabolite profiles of COVID-19 survivors with abnormal pulmonary function were different from those of healthy donors or subjects with normal pulmonary function. These alterations were associated with disease severity and mainly involved amino acid and glycerophospholipid metabolic pathways. Furthermore, increased levels of triacylglycerols, phosphatidylcholines, prostaglandin E2, arginine, and decreased levels of betain and adenosine were associated with pulmonary CO diffusing capacity and total lung capacity. The global plasma metabolomic profile differed between subjects with abnormal and normal pulmonary function. CONCLUSIONS: Further metabolite-based analysis may help to identify the mechanisms underlying pulmonary dysfunction in COVID-19 survivors, and provide potential therapeutic targets in the future.
Subject(s)
COVID-19 , Humans , Metabolomics , Patient Discharge , SARS-CoV-2 , SurvivorsABSTRACT
BACKGROUND: Oseltamivir is a first-line antiviral drug, especially in primary hospitals. During the ongoing outbreak of coronavirus disease 2019 (COVID-19), most patients with COVID-19 who are symptomatic have used oseltamivir. Considering its popular and important role as an antiviral drug, it is necessary to evaluate oseltamivir in the treatment of COVID-19. OBJECTIVE: To evaluate the effect of oseltamivir against COVID-19. METHODS: Swiss-model was used to construct the structure of the N-terminal RNA-binding domain (NRBD) of the nucleoprotein (NC), papain-like protease (PLpro), and RNA-directed RNA polymerase (RdRp) of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). TM-align program was performed to compare the structure of the viral proteins with the structure of the neuraminidase of influenza A. Molecular docking was used to analyze the theoretical possibility of effective binding of oseltamivir with the active centers of the viral proteins. In vitro study was used to evaluate the antiviral efficiency of oseltamivir against SARS-CoV-2. By clinical case analysis, we statistically evaluated whether the history of oseltamivir use influenced the progression of the disease. RESULTS: The structures of NRBD, PLpro, and RdRp were built successfully. The results from TM-align suggested that the S protein, NRBD, 3C-like protease (3CLpro), PLPrO, and RdRp were structurally similar to the influenza A neuraminidase, with TM-scores of 0.30077, 0.19254, 0.28766, 0.30666, and 0.34047, respectively. Interestingly, the active center of 3CL pro was found to be similar to the active center from the neuraminidase of influenza A. Through an analysis of molecular docking, we discovered that oseltamivir carboxylic acid was more favorable to bind to the active site of 3CLpro effectively, but its inhibitory effect was not strong compared with the positive group. Finally, we used in vitro study and retrospective case analysis to verify our speculations. We found that oseltamivir is ineffective against SARS-CoV-2 in vitro study and the clinical use of oseltamivir did not improve the patients' symptoms and signs and did not slow the disease progression. CONCLUSIONS: We consider that oseltamivir isn't suitable for the treatment of COVID-19. During the outbreak of novel coronavirus, when oseltamivir is not effective for the patients after they take it, health workers should be highly vigilant about the possibility of COVID-19.
Subject(s)
Antiviral Agents/therapeutic use , COVID-19 Drug Treatment , Oseltamivir/therapeutic use , SARS-CoV-2/drug effects , Adult , Aged , Animals , Antiviral Agents/chemistry , Antiviral Agents/metabolism , Catalytic Domain , Chlorocebus aethiops , Coronavirus 3C Proteases/antagonists & inhibitors , Coronavirus 3C Proteases/chemistry , Coronavirus 3C Proteases/metabolism , Coronavirus Nucleocapsid Proteins/chemistry , Coronavirus Nucleocapsid Proteins/metabolism , Cysteine Proteinase Inhibitors/metabolism , Cysteine Proteinase Inhibitors/therapeutic use , Female , Humans , Male , Middle Aged , Molecular Docking Simulation , Oseltamivir/chemistry , Oseltamivir/metabolism , Phosphoproteins/chemistry , Phosphoproteins/metabolism , Protein Binding , RNA-Dependent RNA Polymerase/chemistry , RNA-Dependent RNA Polymerase/metabolism , Retrospective Studies , Vero CellsABSTRACT
BACKGROUND: Coronavirus disease 2019 (COVID-19) has become a public health emergency of global concern. We aimed to explore the risk factors of 14-day and 28-day mortality and develop a model for predicting 14-day and 28-day survival probability among adult hospitalized patients with COVID-19. METHODS: In this multicenter, retrospective, cohort study, we examined 828 hospitalized patients with confirmed COVID-19 hospitalized in Wuhan Union Hospital and Central Hospital of Wuhan between January 12 and February 9, 2020. Among the 828 patients, 516 and 186 consecutive patients admitted in Wuhan Union Hospital were enrolled in the training cohort and the validation cohort, respectively. A total of 126 patients hospitalized in Central Hospital of Wuhan were enrolled in a second external validation cohort. Demographic, clinical, radiographic, and laboratory measures; treatment; proximate causes of death; and 14-day and 28-day mortality are described. Patients' data were collected by reviewing the medical records, and their 14-day and 28-day outcomes were followed up. RESULTS: Of the 828 patients, 146 deaths were recorded until May 18, 2020. In the training set, multivariate Cox regression indicated that older age, lactate dehydrogenase level over 360 U/L, neutrophil-to-lymphocyte ratio higher than 8.0, and direct bilirubin higher than 5.0 µmol/L were independent predictors of 28-day mortality. Nomogram scoring systems for predicting the 14-day and 28-day survival probability of patients with COVID-19 were developed and exhibited strong discrimination and calibration power in the two external validation cohorts (C-index, 0.878 and 0.839). CONCLUSION: Older age, high lactate dehydrogenase level, evaluated neutrophil-to-lymphocyte ratio, and high direct bilirubin level were independent predictors of 28-day mortality in adult hospitalized patients with confirmed COVID-19. The nomogram system based on the four factors revealed good discrimination and calibration, suggesting good clinical utility.