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1.
Chinese Journal of Virology ; 36(6):1009-1013, 2020.
Article in Chinese | GIM | ID: covidwho-2034140

ABSTRACT

To determine if a method to detect antibodies against SARS-CoV-2 can be applied clinically. In this retrospective study, the sera samples of 39 patients with newly diagnosed coronavirus disease 2019 (COVID- 19) and 90 healthy people were analyzed by antibody-detection reagents within enzyme-linked immunosorbent assays. The sera samples of confirmed cases at different onset times and 40 suspected cases were also tested. Then. we combined the results of antibody tests. nucleic-acid tests, and patient data. The sensitivity and specificity for SARS-COV-2-specific total antibodies was 92.31% and 100%, respectively. The production time of total antibodies in serum samples increased with time. and the median detection time was 13 days. The result of antibody testing of one confirmed case preceded the result of the nucleic-acid test. Moreover, the antibodies 0f 40 suspected cases were all negative. Detection of the total antibodies against SARS-CoV-2 can be used as an auxiliary diagnostic indicator of infection by this virus, as well as a supplementary means to exclude suspected cases/populations in areas with a high prevalence of negative detection of the nucleic acids of SARS-CoV-2.

2.
Remote Sensing ; 14(14):N.PAG-N.PAG, 2022.
Article in English | Academic Search Complete | ID: covidwho-1974884

ABSTRACT

The concentration changes of aerosols have attracted wide-ranging attention during the COVID-19 lockdown (CLD) period, but the studies involving aerosol optical properties (AOPs) are relatively insufficient, mainly AOD (fine-mode AOD (AODf) and coarse-mode AOD (AODc)), aerosol absorption optical depth (AAOD), and aerosol extinction coefficient (AEC). Here, the remote-sensing observations, Modern-Era Retrospective analysis for Research and Applications, Version 2 (MERRA-2) products, backward-trajectory, and potential-source-contribution models are used to assess the impact of AOPs, vertical distribution, and possible sources on the atmosphere environment in North China Plain (NCP), Central China (CC), Yangtze River Delta (YRD), Pearl River Delta (PRD), and Sichuan Basin (SB) during the CLD period. The results demonstrate that both AOD (MODIS) and near-surface AEC (CALIPSO, <2 km) decreased in most areas of China. Compared with previous years (average 2017–2019), the AOD (AEC) of NCP, CC, YRD, PRD, and SB reduced by 3.33% (10.76%), 14.36% (32.48%), 10.80% (29.64%), 31.44% (22.68%), and 15.50% (8.44%), respectively. In addition, MODIS (AODc) and MERRA-2 (AODc) decreased in the five study areas compared with previous years, so the reduction in dust activities also contributed to improving regional air quality during the epidemic. Despite the reduction of anthropogenic emissions (AODf) in most areas of China during the CLD periods, severe haze events (AODf > 0.6) still occurred in some areas. Compared to previous years, there were increases in BC, OC (MERRA-2), and national raw coal consumption during CLD. Therefore, emissions from some key sectors (raw coal heating, thermal power generation, and residential coal) did not decrease, and this may have increased AODf during the CLD. Based on backward -rajectory and potential source contribution models, the study area was mainly influenced by local anthropogenic emissions, but some areas were also influenced by northwestern dust, Southeast Asian biomass burning, and marine aerosol transport. This paper underscores the importance of emissions from the residential sector and thermal power plants for atmospheric pollution in China and suggests that these sources must be taken into account in developing pollution-mitigation plans. [ FROM AUTHOR] Copyright of Remote Sensing is the property of MDPI and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full . (Copyright applies to all s.)

3.
Cell Mol Life Sci ; 79(6): 309, 2022 May 21.
Article in English | MEDLINE | ID: covidwho-1919755

ABSTRACT

Blood clot formation induced by dysfunctional coagulation is a frequent complication of coronavirus disease 2019 (COVID-19) and a high-risk factor for severe illness and death. Neutrophil extracellular traps (NETs) are implicated in COVID-19-induced immunothrombosis. Furthermore, human cathelicidin, a NET component, can perturb the interaction between the SARS-CoV-2 spike protein and its ACE2 receptor, which mediates viral entry into cells. At present, however, the levels of cathelicidin antimicrobial peptides after SARS-CoV-2 infection and their role in COVID-19 thrombosis formation remain unclear. In the current study, we analyzed coagulation function and found a decrease in thrombin time but an increase in fibrinogen level, prothrombin time, and activated partial thromboplastin time in COVID-19 patients. In addition, the cathelicidin antimicrobial peptide LL-37 was upregulated by the spike protein and significantly elevated in the plasma of patients. Furthermore, LL-37 levels were negatively correlated with thrombin time but positively correlated with fibrinogen level. In addition to platelet activation, cathelicidin peptides enhanced the activity of coagulation factors, such as factor Xa (FXa) and thrombin, which may induce hypercoagulation in diseases with high cathelicidin peptide levels. Injection of cathelicidin peptides promoted the formation of thrombosis, whereas deletion of cathelicidin inhibited thrombosis in vivo. These results suggest that cathelicidin antimicrobial peptide LL-37 is elevated during SARS-CoV-2 infection, which may induce hypercoagulation in COVID-19 patients by activating coagulation factors.


Subject(s)
Antimicrobial Cationic Peptides , COVID-19 , Thrombosis , Blood Coagulation Factors , COVID-19/complications , Fibrinogen , Humans , SARS-CoV-2 , Spike Glycoprotein, Coronavirus , Thrombosis/virology
4.
Nonlinear Dyn ; 101(3): 1981-1993, 2020.
Article in English | MEDLINE | ID: covidwho-1906361

ABSTRACT

Due to the strong infectivity of COVID-19, it spread all over the world in about three months and thus has been studied from different aspects including its source of infection, pathological characteristics, diagnostic technology and treatment. Yet, the influences of control strategies on the transmission dynamics of COVID-19 are far from being well understood. In order to reveal the mechanisms of disease spread, we present dynamical models to show the propagation of COVID-19 in Wuhan. Based on mathematical analysis and data analysis, we systematically explore the effects of lockdown and medical resources on the COVID-19 transmission in Wuhan. It is found that the later lockdown is adopted by Wuhan, the fewer people will be infected in Wuhan, and nevertheless it will have an impact on other cities in China and even the world. Moreover, the richer the medical resources, the higher the peak of new infection, but the smaller the final scale. These findings well indicate that the control measures taken by the Chinese government are correct and timely.

5.
Mathematics ; 10(10):1732, 2022.
Article in English | ProQuest Central | ID: covidwho-1871931

ABSTRACT

China’s livestock output has been growing, but domestic livestock products such as beef, mutton and pork have been unable to meet domestic consumers’ demands. The imbalance between supply and demand causes unstable livestock prices and affects profits on livestock. Therefore, the purpose of this paper is to provide the optimal breeding strategy for livestock farmers to maximize profits and adjust the balance between supply and demand. Firstly, when the price changes, livestock farmers will respond in two ways: by not adjusting the scale of livestock with the price or adjusting the scale with the price. Therefore, combining the model of price and the behavior of livestock farmers, two livestock breeding models were established. Secondly, we proposed four optimal breeding strategies based on the previously studied models and the main research method is Pontryagin’s Maximum Principle. Optimal breeding strategies are achieved by controlling the growth and output of livestock. Further, their existence was verified. Finally, we simulated two situations and found the most suitable strategy for both situations by comparing profits of four strategies. From that, we obtained several conclusions: The optimal strategy under constant prices is not always reasonable. The effect of price on livestock can promote a faster balance. To get more profits, the livestock farmers should adjust the farm’s productivity reasonably. It is necessary to calculate the optimal strategy results under different behaviors.

6.
Journal of Shandong University ; 58(5):46-50, 2020.
Article in English, Chinese | GIM | ID: covidwho-1812842

ABSTRACT

Objective: To evaluate the application value of chemiluminescent immunoassay in the detection of 2019-nCoV antibodies.

7.
EuropePMC; 2022.
Preprint in English | EuropePMC | ID: ppcovidwho-330303

ABSTRACT

Objective: To gain a better understanding of decisions around adherence to self-isolation advice during the first phase of the COVID-19 response in England. Design: A mixed-methods cross sectional study. Setting: England Participants COVID-19 cases and contacts who were contacted by Public Health England (PHE) during the first phase of the response in England (January-March 2020). Results: Of 250 respondents who were advised to self-isolate, 63% reported not leaving home at all during their isolation period, 20% reported leaving only for lower risk activities (dog walking or exercise) and 16% reported leaving for potentially higher risk, reasons (shopping, medical appointments, childcare, meeting family or friends). Factors associated with adherence to never going out included: the belief that following isolation advice would save lives, experiencing COVID-19 symptoms, being advised to stay in their room (rather than just inside), having help from outside and having regular contact by text message from PHE. Factors associated with non-adherence included being angry about the advice to isolate, being unable to get groceries delivered and concerns about losing touch with friends and family. Interviews highlighted that a sense of duty motivated people to adhere to isolation guidance and where people did leave their homes, these decisions were based on rational calculations of the risk of transmission;people would only leave their homes when they thought they were unlikely to come into contact with others. Conclusions: Measures of adherence should be nuanced to allow for the adaptations people make to their behaviour during isolation. Understanding adherence to isolation and associated reasoning during the early stages of the pandemic is an essential part of pandemic preparedness for future emerging infectious diseases.

8.
Nat Hazards (Dordr) ; 111(1): 507-522, 2022.
Article in English | MEDLINE | ID: covidwho-1739394

ABSTRACT

The U.S. 2020 hurricane season was extraordinary because of a record number of named storms coinciding with the COVID-19 pandemic. This study draws lessons on how individual hurricane preparedness is influenced by the additional risk stemming from a pandemic, which turns out to be a combination of perceptions of flood and pandemic risks that have opposite effects on preparedness behavior. We conducted a survey in early June 2020 of 600 respondents in flood-prone areas in Florida to obtain insights into households' risk perceptions and preparedness for the upcoming hurricane season under COVID-19. The results show that concerns over COVID-19 dominated flood risk perceptions and negatively impacted people's evacuation intentions. Whereas hotel costs were the main obstacle to evacuating during Hurricane Dorian in 2019 in the same geographic study area, the main evacuation obstacle identified in the 2020 hurricane season is COVID-19. Our statistical analyses investigating the factors influencing evacuation intentions show that older individuals are less likely to evacuate under a voluntary order, because they are more concerned about the consequences of becoming infected by COVID-19. We observe similar findings based on a real-time survey we conducted in Florida with another group of respondents under the threat of Hurricane Eta at the end of the hurricane season in November 2020. We discuss the implications of our findings for risk communication and emergency management policies that aim to improve hurricane preparedness when dealing with additional health risks such as a pandemic, a situation that may be exacerbated under the future climate. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1007/s11069-021-05064-2.

9.
Results Phys ; 35: 105300, 2022 Apr.
Article in English | MEDLINE | ID: covidwho-1702895

ABSTRACT

On November 26, 2021, the World Health Organization (WHO) announced a new variant of concern of SARS-CoV2 called Omicron. This variant has biological-functional characteristics such as to make it much faster in the infectious process so as to show an even more intense spread. Although many data are currently incomplete, it is possible to identify, based on the viral biochemical characteristics, a possible therapy consisting of a monoclonal antibody called Sotrovimab. The model proposed here is based on the mathematical analysis of the dynamics of action of this monoclonal antibody and two cell populations: the immune memory cells and the infected cells. Indeed, a delay exists during the physiological immune response and the response induced by administration of Sotrovimab. This manuscript presents that delay in a novel manner. The model is developed with the aid of information based on the chemical kinetics. The machine learning tools have been used to satisfy the criteria designed by the dynamical analysis. Regression learner tools of Python are used as the reverse engineering tools for the understanding of the balance in the mathematical model, maintained by the parameters and their corresponding intervals and thresholds set by the dynamical analysis.

10.
EuropePMC; 2020.
Preprint in English | EuropePMC | ID: ppcovidwho-325064

ABSTRACT

When everyone focuses on 2019 coronavirus disease (COVID-19) in Hubei province, the epidemic in other province cannot be ignored, which also has an impact on the epidemic in the whole country. The most distinctive epidemic characteristic in all regions except Wuhan is that the most of confirmed cases are imported cases from Wuhan, and the propagation chain is relatively clear. Based on detailed contact tracing information of confirmed cases, combined with first-order outbreak response measures, we establish a disease transmission dynamical model to describe the infection propagation chain among the human population. Using Shanxi province as a case, modeling results indicate that the epidemic peak in Shanxi province occurred in February 2. In addition, our model suggests that according to the current development trend, COVID-19 will disappear in February with the final epidemic number of approximately 175 cases. It is verified that the most effective outbreak control measures in Shanxi include home isolation of people, surveillance and isolation of second-generation cases, contact tracing and management of contacts. With the end of the holiday, if the average number of contacts per person per day is less than 6 , it has little impact on the incidence of COVID-19, and even if third- and fourth-generation cases occur, the epidemic will be under control, no later than late March with a finial outbreak size of 220 cases. However, if the average number of contacts per person per day is greater than 6, the number of COVID-19 cases will continue to be reported resulting in another epidemic peak. Through the forecast and evaluation of COVID-19 in Shanxi, it is verified that the model with infection generations is more accurate to describe the spread mode and can be extended to regions with imported cases.

11.
EuropePMC; 2020.
Preprint in English | EuropePMC | ID: ppcovidwho-322523

ABSTRACT

Hypercytokinemia is a critically fatal factor in COVID-19. However, underlying pathogenic mechanisms are unknown. Here we show that fibrinogen and leukotriene-A4 hydrolase (LTA4H), two of the most potent inflammatory contributors, are elevated by 67.7 and astonishing 227.7% in the plasma of patients infected by SARS-CoV-2 and admitted to intensive care unit in comparison with healthy control, respectively. Conversely, transferrin identified as a fibrinogen immobilizer in our recent work and Spink6 are down-regulated by 40.3 and 25.9%, respectively. Furthermore, we identify Spink6 as the first endogenous inhibitor of LTA4H, a pro-inflammatory enzyme catalyzing final and rating limited step in biosynthesis of leukotriene-B4 that is an extremely inflammatory mediator and a target to design superior anti-inflammatory drugs. Additionally, virus Spike protein is found to evoke LTA4H and fibrinogen expression in vivo. Collectively, these findings identify the imbalance between inflammatory drivers and antagonists, which likely contributes to hypercytokinemia in COVID-19. Spink6 may have superior anti-inflammatory function because it specifically targets epoxide hydrolase of LTA4H to inhibit leukotriene-B4 biosynthesis without effecting LTA4H’s aminopeptidase activity.

12.
SSRN; 2021.
Preprint in English | SSRN | ID: ppcovidwho-297136

ABSTRACT

The concentration changes of aerosols have attracted wide-ranging attention during the COVID-19 lockdown (CLD) period, but the study involving the aerosol vertical distribution and potential sources is relatively insufficient. Here, the satellite observations, backward trajectory and potential source contribution models are used to assess the impact of aerosol optical properties, vertical distribution and potential source on atmosphere environment in North China Plain (NCP), Central China (CC), Yangtze River Delta (YRD), Pearl River Delta (PRD), and Sichuan Basin (SB) during the CLD period. The results demonstrate that the CLD measures significantly decreased aerosol concentrations in most study areas, especially in both AOD and AAOD of CC, YRD and PRD have sharply reduced compared to the Pre-CLD period (January 3 to 23, 2020) and previous years. During the CLD-I period (January 24 to February 13, 2020), compared with the Pre-CLD period, the aerosol extinction coefficient (AEC) near the surface in all study areas decreased by 9.33%, 40.40%, 59.85%, 10.29%, 32.17%, respectively. Although most cities have been unblocked during the CLD-II period (February 14 to April 8, 2020), the AEC (<2km) in the study regions is still significantly lower than that of Pre-CLD and former years. In addition, the CLD measures also caused an increase in the proportion of anthropogenic aerosols (AA) in NCP, CC, and PRD during the CLD-I period compared with the Pre-CLD and prior years, while the nature aerosols (NA) were smaller than in past years. The proportion of AA (30.03%) and NA (-29.4%) in CC is changed most drastically compared with prior years. Combined with the analysis of backward trajectory and potential sources, NCP is greatly affected by the transmission of dust in Northwest China, but local pollution emissions mainly control CC. Therefore, it is indispensable to strengthen regional joint prevention and control to improve regional air quality.

13.
Pharmacol Res ; 174: 105955, 2021 12.
Article in English | MEDLINE | ID: covidwho-1487920

ABSTRACT

Severe Coronavirus Disease 2019 (COVID-19) is characterized by numerous complications, complex disease, and high mortality, making its treatment a top priority in the treatment of COVID-19. Integrated traditional Chinese medicine (TCM) and western medicine played an important role in the prevention, treatment, and rehabilitation of COVID-19 during the epidemic. However, currently there are no evidence-based guidelines for the integrated treatment of severe COVID-19 with TCM and western medicine. Therefore, it is important to develop an evidence-based guideline on the treatment of severe COVID-19 with integrated TCM and western medicine, in order to provide clinical guidance and decision basis for healthcare professionals, public health personnel, and scientific researchers involved in the diagnosis, treatment, and care of COVID-19 patients. We developed and completed the guideline by referring to the standardization process of the "WHO handbook for guideline development", the Grading of Recommendations Assessment, Development and Evaluation (GRADE) system, and the Reporting Items for Practice Guidelines in Healthcare (RIGHT).


Subject(s)
Antiviral Agents/therapeutic use , COVID-19/drug therapy , Drugs, Chinese Herbal/therapeutic use , Infectious Disease Medicine/trends , Medicine, Chinese Traditional/trends , SARS-CoV-2/drug effects , Antiviral Agents/adverse effects , COVID-19/diagnosis , COVID-19/virology , Consensus , Delphi Technique , Drugs, Chinese Herbal/adverse effects , Evidence-Based Medicine/trends , Host-Pathogen Interactions , Humans , Patient Acuity , SARS-CoV-2/pathogenicity , Treatment Outcome
14.
Natural Hazards (Dordrecht, Netherlands) ; : 1-16, 2021.
Article in English | EuropePMC | ID: covidwho-1472797

ABSTRACT

The U.S. 2020 hurricane season was extraordinary because of a record number of named storms coinciding with the COVID-19 pandemic. This study draws lessons on how individual hurricane preparedness is influenced by the additional risk stemming from a pandemic, which turns out to be a combination of perceptions of flood and pandemic risks that have opposite effects on preparedness behavior. We conducted a survey in early June 2020 of 600 respondents in flood-prone areas in Florida to obtain insights into households’ risk perceptions and preparedness for the upcoming hurricane season under COVID-19. The results show that concerns over COVID-19 dominated flood risk perceptions and negatively impacted people’s evacuation intentions. Whereas hotel costs were the main obstacle to evacuating during Hurricane Dorian in 2019 in the same geographic study area, the main evacuation obstacle identified in the 2020 hurricane season is COVID-19. Our statistical analyses investigating the factors influencing evacuation intentions show that older individuals are less likely to evacuate under a voluntary order, because they are more concerned about the consequences of becoming infected by COVID-19. We observe similar findings based on a real-time survey we conducted in Florida with another group of respondents under the threat of Hurricane Eta at the end of the hurricane season in November 2020. We discuss the implications of our findings for risk communication and emergency management policies that aim to improve hurricane preparedness when dealing with additional health risks such as a pandemic, a situation that may be exacerbated under the future climate. Supplementary Information The online version contains supplementary material available at 10.1007/s11069-021-05064-2.

15.
Microbiol Spectr ; 9(1): e0026121, 2021 09 03.
Article in English | MEDLINE | ID: covidwho-1341309

ABSTRACT

The dynamics of quasispecies afford RNA viruses a great fitness on cell tropism and host range. To study the quasispecies features and the intra-host evolution of SARS-CoV-2, we collected nine confirmed patients and sequenced the haplotypes of spike gene using a single-molecule real-time platform. Fourteen samples were extracted from sputum, nasopharyngeal swabs, or stool, which in total produced 283,655 high-quality circular consensus sequences. We observed a stable quasispecies structure that one master mutant (mean abundance ∼0.70), followed by numerous minor mutants (mean abundance ∼1.21 × 10-3). Under high selective pressure, minor mutants may obtain a fitness advantage and become the master ones. The later predominant substitution D614G existed in the minor mutants of more than one early patient. An epidemic variant had a possibility to be independently originated from multiple hosts. The mutant spectrums covered ∼85% amino acid variations of public genomes (GISAID; frequency ≥ 0.1) and likely provided an advantage mutation pool for the current/future epidemic variants. Notably, 32 of 35 collected antibody escape substitutions were preexistent in the early quasispecies. Virus populations in different tissues/organs revealed potentially independent replications. The quasispecies complexity of sputum samples was significantly lower than that of nasopharyngeal swabs (P = 0.02). Evolution analysis revealed that three continuous S2 domains (HR1, CH, and CD) had undergone a positive selection. Cell fusion-related domains may play a crucial role in adapting to the intrahost immune system. Our findings suggested that future epidemiologic investigations and clinical interventions should consider the quasispecies information that has missed by routine single consensus genome. IMPORTANCE RNA virus population in a host does not consist of a consensus single haplotype but rather an ensemble of related sequences termed quasispecies. The dynamics of quasispecies afford SARS-CoV-2 a great ability on genetic fitness during intrahost evolution. The process is likely achieved by changing the genetic characteristics of key functional genes, such as the spike glycoprotein. Previous studies have applied the next-generation sequencing (NGS) technology to evaluate the quasispecies of SARS-CoV-2, and results indicated a low genetic diversity of the spike gene. However, the NGS platform cannot directly obtain the full haplotypes without assembling, and it is also difficult to predict the extremely low-frequency variations. Therefore, we introduced a single-molecule real-time technology to directly obtain the haplotypes of the RNA population and further study the quasispecies features and intrahost evolution of the spike gene.


Subject(s)
Epidemics , Mutation , Quasispecies , SARS-CoV-2/classification , SARS-CoV-2/genetics , Adult , Aged , Base Sequence , COVID-19/virology , Child , Female , Genome, Viral , High-Throughput Nucleotide Sequencing , Humans , Male , Middle Aged , Spike Glycoprotein, Coronavirus/genetics
16.
J Psychosoc Nurs Ment Health Serv ; 59(11): 18-24, 2021 Nov.
Article in English | MEDLINE | ID: covidwho-1305846

ABSTRACT

This is the first study to assess nurses' attitudes and skills regarding grief counseling for bereaved family members of patients who died from coronavirus disease 2019 (COVID-19) in Wuhan, China. Using a cross-sectional design, 412 nurses selected through convenience sampling completed a demographic characteristics survey, Attitudes of Grief Counseling Scale, (AGCS) and Skills of Grief Counseling Scale (SGCS). Average AGCS score was 32.89 (SD = 9.46), with an overall percentage rate score of 65.6%. Factors influencing attitudes toward grief counseling included other grief counseling skills, educational level, communication skills, and training related to grief counseling (p < 0.05). Average SGCS score was 18.81 (SD = 4.25), with an overall percentage rate score of 58.7%. Factors influencing skills of grief counseling included responsibilities and roles, frequency of contact with the bereaved, and positive view of grief counseling (p < 0.05). Nurses' attitudes and skills regarding grief counseling were low, indicating an urgent need to improve grief counseling. [Journal of Psychosocial Nursing and Mental Health Services, 59(11), 18-24.].


Subject(s)
COVID-19 , Nurses , China , Counseling , Cross-Sectional Studies , Family , Grief , Humans , SARS-CoV-2 , Surveys and Questionnaires
17.
Disaster Med Public Health Prep ; : 1-6, 2021 Apr 30.
Article in English | MEDLINE | ID: covidwho-1294392

ABSTRACT

OBJECTIVE: This research aimed to examine health-care workers' grief counseling for bereaved families of coronavirus disease 2019 (COVID-19) victims in China. Our research may provide a new opportunity to stimulate development of grief counseling in China. METHODS: A cross-sectional survey was conducted with 724 health-care workers selected by convenience sampling from 7 hospitals in Wuhan. Data collection tools included a sociodemographic questionnaire, the skills of grief counseling scale (SGCS), and the attitudes of grief counseling scale (AGCS). RESULTS: The average SGCS score was 18.96 ± 4.66, whose influencing factors consisted of sense of responsibility, frequency of contact with bereaved families, and relevant training (P < 0.05). The average AGCS score was 33.36 ± 8.70, whose influencing factors consisted of other grief counseling skills, communication skills, education background, and relevant training (P < 0.05). CONCLUSIONS: The skills and attitudes toward grief counseling among health-care workers combating COVID-19 were at a lower level in Wuhan, China, indicating the need to build a comprehensive grief counseling system, establish a standardized training course, and strengthen the popularization of grief counseling services to the public.

18.
Complexity ; 2021, 2021.
Article in English | ProQuest Central | ID: covidwho-1177599

ABSTRACT

Coronavirus disease (COVID-19) cases and COVID-19-related deaths have been increasing worldwide since the outbreak in 2019. Before the mass vaccination campaign for COVID-19, the main methods for COVID-19 control in China were mass testing and quarantine. Based on the transmission mechanism of COVID-19, we constructed a dynamic model for COVID-19 transmission in two typical regions: Beijing and Xinjiang. We calculated the basic reproduction number R0, proved the global stability of COVID-19 transmission via the Lyapunov function technique, and introduced the final size. We assessed the effectiveness of mass testing and quarantine. Sensitivity analysis indicated that the more the people were tested per day, the larger is the quarantine proportionality coefficient, the earlier the source location was determined, and the better is the controlling effect. In addition, it was more effective to increase the coefficient of quarantine if the population density in the region was low. To eliminate the pandemic, the government has to expand testing and quarantine, requiring a large amount of continuous manpower, material, and financial resources. Therefore, new control measures should be developed.

19.
Infect Dis Model ; 6: 618-631, 2021.
Article in English | MEDLINE | ID: covidwho-1169180

ABSTRACT

In 2020, an unexpectedly large outbreak of the coronavirus disease 2019 (COVID-19) epidemic was reported in mainland China. As we known, the epidemic was caused by imported cases in other provinces of China except for Hubei in 2020. In this paper, we developed a differential equation model with tracing isolation strategy with close contacts of newly confirmed cases and discrete time imported cases, to perform assessment and risk analysis for COVID-19 outbreaks in Tianjin and Chongqing city. Firstly, the model behavior without imported cases was given. Then, the real-time regeneration number in Tianjin and Chongqing city revealed a trend of rapidly rising, and then falling fast. Finally, sensitivity analysis demonstrates that the earlier with Wuhan lock-down, the fewer cases in these two cities. One can obtain that the tracing isolation of close contacts of newly confirmed cases could effectively control the spread of the disease. But it is not sensitive for the more contact tracing isolation days on confirmed cases, the fewer cases. Our investigation model could be potentially helpful to provide model building technology for the transmission of COVID-19.

20.
Appl Intell (Dordr) ; 51(5): 3074-3085, 2021.
Article in English | MEDLINE | ID: covidwho-1120033

ABSTRACT

This paper proposes a susceptible exposed infectious recovered model (SEIR) with isolation measures to evaluate the COVID-19 epidemic based on the prevention and control policy implemented by the Chinese government on February 23, 2020. According to the Chinese government's immediate isolation and centralized diagnosis of confirmed cases, and the adoption of epidemic tracking measures on patients to prevent further spread of the epidemic, we divide the population into susceptible, exposed, infectious, quarantine, confirmed and recovered. This paper proposes an SEIR model with isolation measures that simultaneously investigates the infectivity of the incubation period, reflects prevention and control measures and calculates the basic reproduction number of the model. According to the data released by the National Health Commission of the People's Republic of China, we estimated the parameters of the model and compared the simulation results of the model with actual data. We have considered the trend of the epidemic under different incubation periods of infectious capacity. When the incubation period is not contagious, the peak number of confirmed in the model is 33,870; and when the infectious capacity is 0.1 times the infectious capacity in the infectious period, the peak number of confirmed in the model is 57,950; when the infectious capacity is doubled, the peak number of confirmed will reach 109,300. Moreover, by changing the contact rate in the model, we found that as the intensity of prevention and control measures increase, the peak of the epidemic will come earlier, and the peak number of confirmed will also be significantly reduced. Under extremely strict prevention and control measures, the peak number of confirmed cases has dropped by nearly 50%. In addition, we use the EEMD method to decompose the time series data of the epidemic, and then combine the LSTM model to predict the trend of the epidemic. Compared with the method of directly using LSTM for prediction, more detailed information can be obtained.

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