Support vector regression model for flight demand forecasting

Flight demand forecasting is a particularly critical component for airline revenue management because of the direct influence on the booking limits that determine airline profits. The traditional flight demand forecasting models generally only take day of the week (DOW) and the current data collection point (DCP) adds up bookings as the model input and uses linear regression, exponential smoothing, pick-up as well as other models to predict the final bookings of flights. These models can be regarded as time series flight demand forecasting models based on the interval between the current date and departure date. They fail to consider the early bookings change features in the specific flight pre-sale period, and have weak generalization ability, at last, they will lead to poor adaptability to the random changes of flight bookings. The support vector regression (SVR) model, which is derived from machine learning, has strong adaptability to nonlinear random changes of data and can adaptively learn the random disturbances of flight bookings. In this paper, flight bookings are automatically divided into peak, medium, and off (PMO) according to the season attribute. The SVR model is trained by using the vector composed of historical flight bookings and adding up bookings of DCP in the early stage of the flight pre-sale period. Compared with the traditional models, the priori information of flight is increased. We collect 2 years of domestic route bookings data of an airline in China before COVID-19 as the training and testing datasets, and divide these data into three categories: tourism, business, and general, the numerical results show that the SVR model significantly improves the forecasting accuracy and reduces RMSE compared with the traditional models. Therefore, this study provides a better choice for flight demand forecasting.

The global response: How cities and provinces around the globe tackled COVID-19 outbreaks in 2021—Authors' reply

Third, regarding the inclusion of RT-PCR and RATs in the laboratory tests, as mentioned in the text (page 9 of manuscript), "All cities/provinces except Tokyo (Table 5), relied on using mass testing strategies comprising both rapid antigen tests and standard RT-PCRs.” The number of laboratory tests was gathered from official websites of relevant national reporting authorities. As mentioned in the footnotes of the table, the WHO "had previously suggested a positivity rate of around 3-12% as a general benchmark of adequate testing, along with recommending that test positivity should remain at 5% or lower for 14 days before regions reopen." The point raised by the Ngo et al., has already been addressed in the manuscript.

Efficacy of blood urea nitrogen-to-albumin ratio for predicting prognostic outcomes of inpatients with COVID-19: A meta-analysis.

BACKGROUND: The associations between blood urea nitrogen (BUN)/albumin ratio and poor prognosis in patients with diagnosis of coronavirus disease 2019 (COVID-19) remain to be clarified. METHODS: A search based on 4 electronic databases (i.e., EMBASE, Google scholar, MEDLINE, and Cochrane Library) was performed on June 23, 2022. The association of BUN/Albumin ratio with poor prognostic outcomes, defined as patients with mortality/severe illnesses, were analyzed. RESULTS: Results from analysis of 7 cohort studies (3600 individuals with COVID-19) published between 2020 and 2022 showed a higher BUN/Albumin ratio in the poor-prognosis group (Mean difference:  = 2.838, 95% confidence interval: 2.015-3.66, P < .001, I2 = 92.5%) than the good-prognosis group. Additional investigation into the connection between BUN/Albumin ratio as a binary variable (i.e., high or low) and the risk of poor outcome also supported an association between a higher BUN/Albumin ratio and a poor prognostic risk (odd ratio = 3.009, 95% confidence interval: 1.565-5.783, P = .001, I2 = 93.7%, 5 studies). Merged analysis of poor prognosis produced a sensitivity of 0.76, specificity of 0.72, and area under curve of 0.81. CONCLUSION: This meta-analysis demonstrated a positive correlation between BUN/albumin ratio and poor outcome in patients with COVID-19. Additional large-scale prospective studies are needed to verify our findings.

SARS-CoV-2 Omicron and its current known unknowns: A narrative review.

The emergence of the SARS-CoV-2 Omicron variant (B.1.1.529) has created great global distress. This variant of concern shows multiple sublineages, importantly B.1.1.529.1 (BA.1), BA.1 + R346K (BA.1.1), and B.1.1.529.2 (BA.2), each with unique properties. However, little is known about this new variant, specifically its sub-variants. A narrative review was conducted to summarise the latest findings on transmissibility, clinical manifestations, diagnosis, and efficacy of current vaccines and treatments. Omicron has shown two times higher transmission rates than Delta and above ten times more infectious than other variants over a similar period. With more than 30 mutations in the spike protein's receptor-binding domain, there is reduced detection by conventional RT-PCR and rapid antigen tests. Moreover, the two-dose vaccine effectiveness against Delta and Omicron variants was found to be approximately 21%, suggesting an urgent need for a booster dose to prevent the possibility of breakthrough infections. However, the current vaccines remain highly efficacious against severe disease, hospitalisation, and mortality. Japanese preliminary lab data elucidated that the Omicron sublineage BA.2 shows a higher illness severity than BA.1. To date, the clinical management of Omicron remains unchanged, except for monoclonal antibodies. Thus far, only Bebtelovimab could sufficiently treat all three sub-variants of Omicron. Further studies are warranted to understand the complexity of Omicron and its sub-variants. Such research is necessary to improve the management and prevention of Omicron infection.

Evaluation Of The Impact Of Covid-19 Vaccines On Thyroid Function And Autoimmunity And The Potential Influence Of Pre-existing Thyroid Autoimmunity On Neutralizing Antibody Responses

Objectives: There are concerns for COVID-19 vaccination in causing thyroid dysfunction and triggering thyroid autoimmunity. Also, data on the impact of pre-existing thyroid autoimmunity on COVID-19 vaccination efficacy are limited. We evaluated the impact of COVID-19 vaccination on thyroid function and antibodies, and the influence of pre-existing thyroid autoimmunity on neutralizing antibody (NAb) responses. Methods: Adults without history of COVID-19 or thyroid disorders who received COVID-19 vaccination between 14 June 2021 and 8 August 2021 at three vaccination centers were recruited. All participants received two doses of vaccines. Thyroid-stimulating hormone (TSH), free thyroxine (fT4), free triiodothyronine (fT3), anti-thyroid peroxidase (anti-TPO) and anti-thyroglobulin (anti-Tg) antibodies were measured at baseline and 8 weeks after the first dose of vaccination. Post-vaccination NAb against SARS-CoV-2 receptor-binding domain was measured. Results: In total, 215 individuals were included (129 BNT162b2 [60%] and 86 CoronaVac [40%] recipients): mean age 49.6 years, 37.2% men, and 12.1% positive for anti-TPO/anti-Tg at baseline. After vaccination, TSH levels did not change (p=0.225), but fT4 slightly increased (from 12. 0±1.1 to 12.2±1.2 pmol/L, p<0. 001) and fT3 slightly decreased (from 4.1±0.4 to 4. 0±0.4 pmol/L, p<0. 001). Only 3 patients (1.4%) had abnormal thyroid function after vaccination: two occurred among BNT162b2 recipients - both were subclinical thyrotoxicosis (TSH 0.32mIU/L, fT4 11.51pmol/L and fT3 4.40pmol/L;TSH 0.34mIU/L, fT4 12.67pmol/L and fT3 4.22pmol/L;both were anti-TPO and anti-Tg negative before and after vaccination);one occurred among CoronaVac recipients - isolated mild low fT3 (TSH 0.90mIU/L, fT4 9.94pmol/L and fT3 2.33pmol/L;anti-TPO/Tg negative before and after vaccination). All three recipients were asymptomatic. Both anti-TPO and anti-Tg titers increased modestly after vaccination (anti-TPO: from 7.50 [IQR: 5.90-11.2] to 9.80 IU/mL [IQR: 7.80-13.1], p<0. 001;anti-Tg: from 12.4 [IQR: 11.1-14.9] to 15.7 IU/mL [IQR: 14.2-18.2], p<0. 001), without significant changes in anti-TPO/Tg positivity. Changes in thyroid function and anti-thyroid antibodies were generally consistent between BNT162b2 and CoronaVac recipients, although anti-TPO titer rise was greater after BNT162b2 (p<0. 001). NAb responses were similar between individuals with and without pre-existing thyroid autoimmunity (p=0.855). Conclusion: COVID-19 vaccination was associated with a modest increase in anti-thyroid antibody titers. Anti-TPO increase was greater among BNT162b2 recipients. However, there was no clinically significant thyroid dysfunction 8 weeks post-vaccination. NAb responses were not influenced by pre-existing thyroid autoimmunity. Our results provided important reassurance to people to proceed to COVID-19 vaccination.Presentation: No date and time listed

Association between Recent Antibiotic Use and Early Immunogenicity of Covid-19 Bnt162b2 Vaccine

Introduction: Gut microbiota have been shown to be associated with COVID- 19 and influenza vaccine immunogenicity. While antibiotic-induced gut microbiota perturbation leads to suboptimal antibody production among influenza vaccine recipients, little is known about the effect of preexposure antibiotics on COVID-19 vaccine immunogenicity. Aims & Methods: We aimed to determine whether recent antibiotics use impaired COVID-19 immunogenicity. This was a prospective cohort study recruiting adult BNT162b2 recipients from five vaccination centers in Hong Kong. Exclusion criteria included prior COVID-19 infection, history of gastrointestinal surgery, inflammatory bowel disease, immunocompromised status (post-organ transplantation, immunosuppressants, chemotherapy), cancer, hematological, rheumatological and autoimmune diseases. Subjects received two doses of BNT162b2 at three weeks apart. Blood samples were collected at three time-points (before vaccination, day 21 and 56after first dose), and were tested for neutralising antibody (NAb) against receptor-binding domain (RBD) of wild type SARS-CoV-2 virus using a one-step competitive chemiluminescence immunoassay. NAb seroconversion was defined as 15 AU/mL. Primary outcomes were seroconversion rates of NAb at day 21 and 56 after first dose of vaccine. Exposure was pre-vaccination antibiotic use, defined as ever use of any antibiotics (including 11 different classes) within 6 months before vaccination. The adjusted odds ratio (aOR) of seroconversion with antibiotic use was derived by multivariable logistic regression model by adjusting for age, sex, diabetes mellitus (DM), overweight (BMI >23 kg/m2for Asians), hypertension, raised LDL (>=3.4 mmol/L), moderate-to-severe hepatic steatosis (defined as controlled attenuated parameter >= 268 dB/M on transient elastography), smoking and alcohol. Result(s): Of 316 BNT162b2 recipients (100 [31.6%] male;median age 50.1 [IQR:40.0-57.0] years), all and 284 (89.9%) had NAb level measured at day 21 and 56, respectively. There were 29 (9.2%) antibiotic users (median duration of use: 7 [IQR:7-13] days). There was no significant difference in baseline characteristics between antibiotic users and non-users. At day 21, there was a trend towards lower seroconversion rate among antibiotic users compared with non-users (82.8% vs 91.3%;p=0.135). Independent factors negatively associated with seroconversion after one dose of BNT162b2 were antibiotics use (aOR:0.26, 95% CI:0.08-0.96), age >60 years (aOR:0.34, 95% CI:0.13-0.95) and male sex (aOR:0.14, 95% CI:0.05-0.34). At day 56, there was no more significant difference in seroconversion rate between antibiotic users and non-users (96.6% vs 99.3%;p=0.149). Conclusion(s): Recent antibiotic use before BNT162b2 vaccination was associated with lower early seroconversion rate after a single dose of vaccine but not two doses of vaccine. Further research on the association between antibiotics, gut microbiota and COVID-19 early vaccine immunogenicity is warranted.

Development of a prediction score (ThyroCOVID) for identifying abnormal thyroid function in COVID-19 patients.

PURPOSE: Thyroid dysfunction in COVID-19 carries clinical and prognostic implications. In this study, we developed a prediction score (ThyroCOVID) for abnormal thyroid function (TFT) on admission amongst COVID-19 patients. METHODS: Consecutive COVID-19 patients admitted to Queen Mary Hospital were prospectively recruited during July 2020-May 2021. Thyroid-stimulating hormone (TSH), free thyroxine (fT4) and free triiodothyronine (fT3) were measured on admission. Multivariable logistic regression analysis was performed to identify independent determinants of abnormal TFTs. ThyroCOVID was developed based on a clinical model with the lowest Akaike information criteria. RESULTS: Five hundred and forty six COVID-19 patients were recruited (median age 50 years, 45.4% men, 72.9% mild disease on admission). 84 patients (15.4%) had abnormal TFTs on admission. Patients with abnormal TFTs were more likely to be older, have more comorbidities, symptomatic, have worse COVID-19 severity, higher SARS-CoV-2 viral loads and more adverse profile of acute-phase reactants, haematological and biochemical parameters. ThyroCOVID consisted of five parameters: symptoms (malaise), comorbidities (ischaemic heart disease/congestive heart failure) and laboratory parameters (lymphocyte count, C-reactive protein, and SARS-CoV-2 cycle threshold values). It was able to identify abnormal TFT on admission with an AUROC of 0.73 (95% CI 0.67-0.79). The optimal cut-off of 0.15 had a sensitivity of 75.0%, specificity of 65.2%, negative predictive value of 93.5% and positive predictive value of 28.1% in identifying abnormal TFTs on admission amongst COVID-19 patients. CONCLUSION: ThyroCOVID, a prediction score to identify COVID-19 patients at risk of having abnormal TFT on admission, was developed based on a cohort of predominantly non-severe COVID-19 patients.

The global response: How cities and provinces around the globe tackled Covid-19 outbreaks in 2021.

Background: Tackling the spread of COVID-19 remains a crucial part of ending the pandemic. Its highly contagious nature and constant evolution coupled with a relative lack of immunity make the virus difficult to control. For this, various strategies have been proposed and adopted including limiting contact, social isolation, vaccination, contact tracing, etc. However, given the heterogeneity in the enforcement of these strategies and constant fluctuations in the strictness levels of these strategies, it becomes challenging to assess the true impact of these strategies in controlling the spread of COVID-19. Methods: In the present study, we evaluated various transmission control measures that were imposed in 10 global urban cities and provinces in 2021- Bangkok, Gauteng, Ho Chi Minh City, Jakarta, London, Manila City, New Delhi, New York City, Singapore, and Tokyo. Findings: Based on our analysis, we herein propose the population-level Swiss cheese model for the failures and pitfalls in various strategies that each of these cities and provinces had. Furthermore, whilst all the evaluated cities and provinces took a different personalized approach to managing the pandemic, what remained common was dynamic enforcement and monitoring of breaches of each barrier of protection. The measures taken to reinforce the barriers were adjusted continuously based on the evolving epidemiological situation. Interpretation: How an individual city or province handled the pandemic profoundly affected and determined how the entire country handled the pandemic since the chain of transmission needs to be broken at the very grassroot level to achieve nationwide control. Funding: The present study did not receive any external funding.

Effects of Exergaming on College Students' Situational Interest, Self-Efficacy, and Motion Sickness.

OBJECTIVE: Given the low levels of physical activity (PA) among U.S. college students, the use of exergaming as a supplement to traditional exercise may promote higher levels of motivation and PA. Therefore, this study's purpose was to examine the effect of two different exergames on college students' situational interest (SI), self-efficacy (SE), and equilibrium change (EQC) compared to traditional treadmill walking. METHODS: Sixty college students (30 female; Mage = 23.6 ± 4.1 years; MBMI = 23.9 ± 4.0 kg/m2) participated in three separate 20 min exercise sessions: (1) Xbox 360 Kinect Just Dance; (2) Xbox 360 Kinect Reflex Ridge; and (3) traditional treadmill walking at 4.0 mph. Participants' SI, SE, and EQC were measured after each session using a series of validated surveys. RESULTS: A mixed model analysis of covariance (ANCOVA) with repeated measures evaluated mean differences between exercise sessions for all outcomes. Significant main effects were observed between the three exercise sessions (all p < 0.01). Specifically, Just Dance and Reflex Ridge sessions yielded significantly higher SI scores than treadmill exercise, F (10, 49) = 54.61, p < 0.01, η2 = 0.92. In addition, participants experienced significantly lower EQC in Reflex Ridge than in treadmill exercise, F (2, 58) = 4.26, p = 0.02, η2 = 0.13. No differences were identified for SE. CONCLUSION: The integration of exergaming into traditional exercise routines may help to promote higher levels of SI but not SE amongst college students. RR exergaming also demonstrated low EQC as compared to traditional exercise. Experimental study designs are warranted to provide additional evidence on the efficacy of exergaming.

A prospective study of the impact of glycaemic status on clinical outcomes and anti-SARS-CoV-2 antibody responses among patients with predominantly non-severe COVID-19

OBJECTIVE: We aimed to evaluate the impact of glycaemic status on clinical outcomes and anti-SARS-CoV-2 antibody (Ab) response among patients with predominantly non-severe COVID-19, highly relevant to the current COVID-19 vaccination programme. METHODS: We included consecutive adults admitted to Queen Mary Hospital for COVID-19 from July 2020 to May 2021. Glycaemic status was defined by HbA1c on admission: normoglycaemia (<5.7%), prediabetes (5.7-6.4%) and diabetes (≥6.5% or known diabetes). Clinical deterioration was defined by radiological progression, new oxygen requirement, intensive care unit admission, or death. COVID-19 survivors had Ab measurements at 1-month, 2-month, 3- month and 6-month post-discharge, with a live SARS-CoV-2-based microneutralization assay which correlated well with anti-SARS-CoV-2 receptor binding domain IgG (≥1:20 defined as positive). RESULTS: Among 605 patients (age 50.2 - 17.1 years;45.1% men;96.9% non-severe COVID-19), 325 had normoglycaemia, 185 had prediabetes and 95 had diabetes. 74 had clinical deterioration (12.2%): 16 required intensive care and 4 died. Clinical deterioration was more likely with worse glycaemic status (P < 0.001) and higher HbA1c (OR 1.403, P < 0.001). Older age (P < 0.001), higher viral loads (P < 0.001), higher C-reactive protein (CRP) (P < 0.001) and symptomatic presentation (P = 0.008), but not glycaemic status/HbA1c, independently predicted clinical deterioration. 314 patients had Ab measured upon follow-up (1-month: 295;2-month: 227;3-month: 207;6-month: 122). Ab titres were comparable across glycaemic status throughout follow-up period. CRP (P = 0.003), but not glycaemic status/HbA1c, was the only positive independent determinant of Ab levels. Rate of decline of Ab titre was comparable across glycaemic status, and did not correlate with HbA1c. Furthermore, most patients remained Ab-positive throughout follow-up (1-month: 94.9%, 2-month: 93.8%, 3-month: 87.4%, 6-month 80.3%), similar across glycaemic status. CONCLUSION: Worse glycaemic status was associated with a higher chance of clinical deterioration in COVID-19, contributed by older age, more severe inflammation and higher viral loads. Importantly, glycaemic status did not adversely influence the Ab response.

Mass screening and the low rates of acute kidney injury among COVID-19 patients in Hong Kong

BACKGROUND AND AIMS: Renal involvement in COVID-19 under vigilant public health surveillance, including mass screening and early hospitalization is less wellcharacterized. We assessed renal involvement of COVID-19 patients in Hong Kong, including the association with risk factors, length of hospitalization, critical presentation and mortality. METHOD: Linked electronic records of all confirmed patients from 5 major designated hospitals were extracted. Primary outcome was the incidence of in-hospital AKI. Secondary outcomes were AKI-associated mortality, incident RRT, intensive care admission, prolonged hospitalization and disease course (defined as >90th percentile of hospitalization duration and duration from symptom onset to discharge, respectively), and change of eGFR. Patients were further stratified into being symptomatic or asymptomatic. RESULTS: Patients were characterized by young age (median:38.4, IQR:28.4-55.8 years old) and short time (Median:5, IQR:2-9 days) from symptom onset to admission. Among the 591 patients, 22 (3.72%) developed AKI and 4 (0.68%) required RRT. AKI increased the odds of prolonged hospitalization and disease course by 2.0 and 3.5 folds, respectively. Estimated GFR 24 weeks post-discharge reduced by 7.51 and 1.06 ml/min/ 1.73m2 versus baseline (at admission) in the AKI and non-AKI groups, respectively. The incidence of AKI was comparable between asymptomatic (4.8%) and symptomatic (3.7%) patients. CONCLUSION: The overall rate of AKI among COVID-19 patients in Hong Kong is low, which could be attributable to a vigilant screening program and early hospitalization. Among patients who developed in-hospital AKI, the duration of hospitalization is prolonged and kidney function impairment can persist for up to 6 months post-discharge. Mass surveillance for COVID-19 is warranted in identifying asymptomatic subjects for earlier AKI management.

Mortality and risk factors associated with pulmonary embolism in coronavirus disease 2019 patients: a systematic review and meta-analysis.

To determine, in patients with coronavirus disease 2019 (COVID-19) infection, the associations of pulmonary embolism (PE) with mortality and risk factors for PE as well as the therapeutic benefit of anticoagulant prophylaxis. Embase, PubMed, Cochrane controlled trials register, and Web of Science databases were searched from inception to October 10, 2020. We included all published trials on PE in patients diagnosed with COVID-19 with eligibility of the trials assessed following the PRISMA guidelines. Sixteen clinical trials with 5826 patients were eligible. There were significant associations of PE with the male gender [odd ratio (OR) = 1.59, 95% CI 1.28-1.97], mechanical ventilation (OR = 3.71, 95% CI 2.57-5.36), intensive care unit admission (OR = 2.99, 95% CI 2.11-4.23), circulating D-dimer [mean difference (MD) = 5.04 µg/mL, 95% CI 3.67-6.42) and CRP (MD = 1.97 mg/dL, 95% CI 0.58- 3.35) concentrations without significant correlation between PE and mortality (OR = 1.31, 95% CI 0.82-2.08) as well as other parameters or comorbidities. After omitting one trial with strict patient selection criteria for anticoagulant prophylaxis, significant prophylactic benefit was noted (OR = 0.31, 95% CI 0.1-0.91). Our findings identified the risk factors associated with PE in COVID-19 patients and supported the therapeutic benefit of anticoagulant prophylaxis against PE in this patient population.

Identifying SARS-CoV2 transmission cluster category: An analysis of country government database.

BACKGROUND: As a result of the high contagiousness and transmissibility of SARS-CoV-2, studying the location of the case clusters that will follow, will help understand the risk factors related to the disease transmission. In this study, we aim to identify the transmission cluster category and settings that can guide decision-makers which areas to be opened again. METHODS: A thorough review of the literature and the media articles were performed. After data verification, we included cluster data from eight countries as of 16th May 2020. Clusters were further categorized into 10 categories and analysis was performed. The data was organized and presented in an easily accessible online sheet. RESULTS: Among the eight included countries, we have found 3905 clusters and a total number of 1,907,944 patients. Indoor settings (mass accommodation and residential facilities) comprised the highest number of both number of clusters (3315/3905) and infected patients (1,837,019/1,907,944), while the outdoor ones comprised 590 clusters and 70,925 patients. Mass accommodation was associated with the highest number of cases in 5 of the 7 countries with data available. Social events and residential settings were responsible for the highest number of cases in the two remaining countries. In the USA, workplace facilities have reported 165 clusters of infection including 122 food production facilities. CONCLUSIONS: Lockdown could truly be a huge burden on a country's economy. However, with the proper knowledge concerning the transmissibility and the behaviour of the disease, better decisions could be made to guide the appropriate removal of lockdown across the different fields and regions.

From SARS coronavirus to novel animal and human coronaviruses

In 2003, severe acute respiratory syndrome coronavirus (SARS-CoV) caused one of the most devastating epidemics known to the developed world. There were two important lessons from this epidemic. Firstly, coronaviruses, in addition to influenza viruses, can cause severe and rapidly spreading human infections. Secondly, bats can serve as the origin and natural animal reservoir of deadly human viruses. Since then, researchers around the world, especially those in Asia where SARS-CoV was first identified, have turned their focus to find novel coronaviruses infecting humans, bats, and other animals. Two human coronaviruses, HCoV-HKU1 and HCoV-NL63, were identified shortly after the SARS-CoV epidemic as common causes of human respiratory tract infections. In 2012, a novel human coronavirus, now called Middle East respiratory syndrome coronavirus (MERS-CoV), has emerged in the Middle East to cause fatal human infections in three continents. MERS-CoV human infection is similar to SARS-CoV in having a high fatality rate and the ability to spread from person to person which resulted in secondary cases among close contacts including healthcare workers without travel history to the Middle East. Both viruses also have close relationships with bat coronaviruses. New cases of MERS-CoV infection in humans continue to occur with the origins of the virus still unknown in many cases. A multifaceted approach is necessary to control this evolving MERS-CoV outbreak. Source identification requires detailed epidemiological studies of the infected patients and enhanced surveillance of MERS-CoV or similar coronaviruses in humans and animals. Early diagnosis of infected patients and appropriate infection control measures will limit the spread in hospitals, while social distancing strategies may be necessary to control the outbreak in communities if it remained uncontrolled as in the SARS epidemic. FAU - To, Kelvin K. W.