scholarly journals A COVID-19 Spread Model of the Discrete Grid to Assess the Potential of Non-pharmaceutical Interventions

2021 ◽  
Author(s):  
Wen Cao ◽  
Haoran Dai ◽  
Xiaochong Tong ◽  
Jingwen Zhu ◽  
Yuzhen Tian ◽  
...  
Keyword(s):  
Early Stage ◽  
Transmission Model ◽  
Model Parameters ◽  
Protection Measure ◽  
Protection Measures ◽  
Buffer Time ◽  
Spread Model ◽  
Self Protection ◽  
Discrete Grid ◽  
Quarantine Measure

Abstract Background: The outbreak of COVID-19 posed a serious threat to human health, economic development, and social stability worldwide, and many countries had taken different interventions to control the deterioration of the epidemic. Although many studies have evaluated the effectiveness of these interventions, there were few reasonable explanations for the practical geographic significance of the model parameters. Our aim was to evaluate the potential of different interventions to mitigate the spread of the epidemic, including discussion about the different time and intensity of implementation, and map parameters of model to the practical application meanings of the special interventions.Methods: In this study, a COVID-19 spread model based on the discrete grid was proposed from perspective of geography. A multi-level grid was introduced to describe the quarantine status and intensity in different spaces, which also combined with the model of medical reception-cured and self-protection, and the spatiotemporal evolution process of early COVID-19 spread was simulated based on the spatial correlation, finally, the effect of interventions was quantitatively analyzed by the dynamic transmission model of COVID-19.Results: Quarantine measure were the most effective interventions, which could effectively reduce the peak value of infection, advance the arrival time of the peak, and shorten the duration of the epidemic, but it only played a role under sufficient intensity; the medical reception-cured and self-protection measure could effectively fatten the infection curve and slowed the spread of the epidemic in the early stage, which could provide more buffer time for the relevant government departments, but the practical effect was not obvious because of the limitation of actually invested resources. The role of the medical reception-cured measure was more reflected in the reduction of the number of deaths, and the effect of the self-protection measure could be reduced in strict quarantine measure.Conclusions: Results of the study indicated that the quarantine, medical reception-cured and self-protection measures were effective, and mitigating the spread of COVID-19 by achieving strong interventions was necessary. Strict quarantine should be implementing as soon as possible in countries with serious development of COVID-19.

scholarly journals Analysis and Evaluation of Non-Pharmaceutical Interventions on Prevention and Control of COVID-19: A Case Study of Wuhan City

2021 ◽  
Vol 10 (7) ◽  
pp. 480
Author(s):  
Wen Cao ◽  
Haoran Dai ◽  
Jingwen Zhu ◽  
Yuzhen Tian ◽  
Feilin Peng
Keyword(s):  
Prevention And Control ◽  
Transmission Model ◽  
Model Parameters ◽  
Protection Measures ◽  
Dynamic Transmission Model ◽  
Sufficient Intensity ◽  
And Control ◽  
Self Protection ◽  
The Impact ◽  
Pharmaceutical Interventions

As the threat of COVID-19 increases, many countries have carried out various non-pharmaceutical interventions. Although many studies have evaluated the impact of these interventions, there is a lack of mapping between model parameters and actual geographic areas. In this study, a non-pharmaceutical intervention model of COVID-19 based on a discrete grid is proposed from the perspective of geography. This model can provide more direct and effective information for the formulation of prevention and control policies. First, a multi-level grid was introduced to divide the geographical space, and the properties of the grid boundary were used to describe the quarantine status and intensity in these different spaces; this was also combined with the model of hospital isolation and self-protection. Then, a process for the spatiotemporal evolution of the early COVID-19 spread is proposed that integrated the characteristics of residents’ daily activities. Finally, the effect of the interventions was quantitatively analyzed by the dynamic transmission model of COVID-19. The results showed that quarantining is the most effective intervention, especially for infectious diseases with a high infectivity. The introduction of a quarantine could effectively reduce the number of infected humans, advance the peak of the maximum infected number of people, and shorten the duration of the pandemic. However, quarantines only function properly when employed at sufficient intensity; hospital isolation and self-protection measures can effectively slow the spread of COVID-19, thus providing more time for the relevant departments to prepare, but an outbreak will occur again when the hospital reaches full capacity. Moreover, medical resources should be concentrated in places where there is the most urgent need under a strict quarantine measure.

A qualitative exploration of parental perceptions regarding children’s sun exposure, sun protection, and sunburn

2020 ◽  
Author(s):  
Karlijn Thoonen ◽  
Liesbeth van Osch ◽  
Rowan Drittij ◽  
Hein de Vries ◽  
Francine Schneider
Keyword(s):  
Skin Cancer ◽  
Sun Exposure ◽  
Structured Interview ◽  
Sun Protection ◽  
Parental Perceptions ◽  
Skin Cancer Prevention ◽  
Protection Measure ◽  
Sun Safety ◽  
Protection Measures ◽  
Lack Of Knowledge

Sun protection among children is of utmost importance since sunburn in early life is a major risk factor for skin cancer development. Because parents play a vital role in enhancing sun safety among children, this study explored parental perceptions concerning sun exposure, sun protection behaviors, and sunburn in children. Additionally, the context in which children experience sunburn in order to assist the development, optimization, and targeting of sun safety interventions for parents is revealed.A qualitative study design, using a semi-structured interview guide addressing several themes (e.g. sun exposure, sun protection, and sunburn experiences), was used. Data were collected in the Netherlands in the fall of 2019. Parents were recruited via purposive sampling at schools, youth services centers, and social media. In total, 26 interviews were performed. Execution, transcription, and coding of the interviews was done by two researchers, using the qualitative analyzing program Nvivo (interrater reliability of d =.84). Comprehensive findings concerning various themes were retrieved. It was found that sunburn was frequently prevalent among children, even though all parents reported using at least one sun protection measure. Parents were often unaware of their child’s sunburn and its severity. Regarding sun protection measures, parents demonstrated an overreliance on sunscreen, often failing to adequately protect their children’s skin. Water-related activities, a lack of shade, and lack of knowledge regarding UV-index were often related to sunburn. Moreover, unexpected sun exposure or longer exposure duration than initially planned were reported as challenging situations. The majority of parents had positive perceptions regarding tanned skin for both themselves as for children.This study provides directions for future skin cancer prevention efforts targeted at both parents and their children. Since a lack of knowledge regarding sufficient sun protection measures and sunburn occurrence in various situations was reported, educational efforts are warranted. Additionally, focusing on clothing, shade-seeking, and adequate sunscreen use is recommended to increase children’s sun safety. By intervening in the physical environment as well (e.g. providing shady areas), sun protection barriers can be reduced. Lastly, the general positive attitude toward tanned skin evident in this study is certainly worthy of attention in future interventions.

scholarly journals Evolution of disease transmission during the COVID-19 pandemic: patterns and determinants

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Jie Zhu ◽  
Blanca Gallego
Keyword(s):  
Public Health ◽  
Disease Transmission ◽  
Clustering Algorithm ◽  
Health Interventions ◽  
Transmission Model ◽  
Model Parameters ◽  
Public Health Interventions ◽  
Forecasting Accuracy ◽  
Time Lagged ◽  
The Impact

AbstractEpidemic models are being used by governments to inform public health strategies to reduce the spread of SARS-CoV-2. They simulate potential scenarios by manipulating model parameters that control processes of disease transmission and recovery. However, the validity of these parameters is challenged by the uncertainty of the impact of public health interventions on disease transmission, and the forecasting accuracy of these models is rarely investigated during an outbreak. We fitted a stochastic transmission model on reported cases, recoveries and deaths associated with SARS-CoV-2 infection across 101 countries. The dynamics of disease transmission was represented in terms of the daily effective reproduction number ($$R_t$$ R t ). The relationship between public health interventions and $$R_t$$ R t was explored, firstly using a hierarchical clustering algorithm on initial $$R_t$$ R t patterns, and secondly computing the time-lagged cross correlation among the daily number of policies implemented, $$R_t$$ R t , and daily incidence counts in subsequent months. The impact of updating $$R_t$$ R t every time a prediction is made on the forecasting accuracy of the model was investigated. We identified 5 groups of countries with distinct transmission patterns during the first 6 months of the pandemic. Early adoption of social distancing measures and a shorter gap between interventions were associated with a reduction on the duration of outbreaks. The lagged correlation analysis revealed that increased policy volume was associated with lower future $$R_t$$ R t (75 days lag), while a lower $$R_t$$ R t was associated with lower future policy volume (102 days lag). Lastly, the outbreak prediction accuracy of the model using dynamically updated $$R_t$$ R t produced an average AUROC of 0.72 (0.708, 0.723) compared to 0.56 (0.555, 0.568) when $$R_t$$ R t was kept constant. Monitoring the evolution of $$R_t$$ R t during an epidemic is an important complementary piece of information to reported daily counts, recoveries and deaths, since it provides an early signal of the efficacy of containment measures. Using updated $$R_t$$ R t values produces significantly better predictions of future outbreaks. Our results found variation in the effect of early public health interventions on the evolution of $$R_t$$ R t over time and across countries, which could not be explained solely by the timing and number of the adopted interventions.

scholarly journals High COVID-19 transmission potential associated with re-opening universities can be mitigated with layered interventions

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Ellen Brooks-Pollock ◽  
Hannah Christensen ◽  
Adam Trickey ◽  
Gibran Hemani ◽  
Emily Nixon ◽  
...  
Keyword(s):  
Prediction Interval ◽  
Mitigation Strategies ◽  
Control Measures ◽  
Transmission Model ◽  
Model Parameters ◽  
Infection Rates ◽  
First Year Students ◽  
Transmission Potential ◽  
Plausible Model ◽  
Effective Option

AbstractControlling COVID-19 transmission in universities poses challenges due to the complex social networks and potential for asymptomatic spread. We developed a stochastic transmission model based on realistic mixing patterns and evaluated alternative mitigation strategies. We predict, for plausible model parameters, that if asymptomatic cases are half as infectious as symptomatic cases, then 15% (98% Prediction Interval: 6–35%) of students could be infected during the first term without additional control measures. First year students are the main drivers of transmission with the highest infection rates, largely due to communal residences. In isolation, reducing face-to-face teaching is the most effective intervention considered, however layering multiple interventions could reduce infection rates by 75%. Fortnightly or more frequent mass testing is required to impact transmission and was not the most effective option considered. Our findings suggest that additional outbreak control measures should be considered for university settings.

scholarly journals Lies, Gosh Darn Lies, and Not Enough Good Statistics: Why Epidemic Model Parameter Estimation Fails

2020 ◽  
Author(s):  
Daniel E. Platt ◽  
Laxmi Parida ◽  
Pierre Zalloua
Keyword(s):  
Genetic Association ◽  
Transmission Rate ◽  
Association Studies ◽  
Genetic Association Studies ◽  
Personal Space ◽  
Model Parameters ◽  
Spread Model ◽  
Positive Growth ◽  
Positive Growth Rate ◽  
Rate Limiting

AbstractAn opportunity exists in exploring epidemic modeling as a novel way to determine physiological and demic parameters for genetic association studies on a population/environmental (quasi) epidemiological study level. First, the spread of SARS-COV-2 has produced population specific lineages; second, epidemic spread model parameters are tied directly to these physiological and demic rates (e. g. incubation time, recovery time, transmission rate); and third, these parameters may serve as novel phenotypes to associate with region-specific genetic mutations as well as demic characteristics (e. g. age structure, cultural observance of personal space, crowdedness). Therefore, we sought to understand whether the parameters of epidemic models could be determined from the trajectory of infections, recovery, and hospitalizations prior to peak, and also to evaluate the quality and comparability of data between jurisdictions reporting their statistics necessary for the analysis of model parameters across populations. We found that, analytically, the pre-peak growth of an epidemic is limited by a subset of the model variates, and that the rate limiting variables are dominated by the expanding eigenmode of their equations. The variates quickly converge to the ratio of eigenvector components of the positive growth rate, which determines the doubling time. There are 9 parameters and 4 independent components in the eigenmode, leaving 5 undetermined parameters. Those parameters can be strikingly population dependent, and can have significant impact on estimates of hospital loads downstream. Without a sound framework, measurements of infection rates and other parameters are highly corrupted by uneven testing rates to uneven counting and reporting of relevant values. From the standpoint of phenotype parameters, this means that structured experiments must be performed to estimate these parameters in order to perform genetic association studies, or to construct viable models that accurately predict critical quantities such as hospitalization loads.

scholarly journals MECHANICAL PROTECTION GUIDELINES1

1995 ◽  
Vol 1995 (1) ◽  
pp. 841-842
Author(s):  
Frank Whipple ◽  
Sharon Christopherson ◽  
Jacqueline Michel
Keyword(s):  
Cultural Sensitivity ◽  
Protection Measure ◽  
Protection Measures ◽  
Site Specific ◽  
Physical Conditions ◽  
Exchange Of Information ◽  
Shoreline Protection ◽  
National Response ◽  
Protection Strategies ◽  
Operational Constraints

ABSTRACT The recently published Mechanical Protection Guidelines will:provide guidelines for identifying and prioritizing areas of economic, environmental, and cultural sensitivity, including formats for mapping sensitive areas;describe the types of shoreline protection measures available, with emphasis on limits and requirements of each protection measure;provide guidance on developing site-specific protection strategies, including equipment and logistics needed, operational constraints, and physical conditions of the site (charts and tables are included as tools for development of the most feasible and successful strategies); andprovide continuity among area plans, to facilitate exchange of information and use by regional and national response teams.

scholarly journals Using and Explaining Individual Dosimetry Data

2017 ◽  
Vol 29 (2_suppl) ◽  
pp. 110S-119S ◽  
Author(s):  
Makoto Miyazaki
Keyword(s):  
Nuclear Power ◽  
Large Scale ◽  
Measurement Data ◽  
Lessons Learned ◽  
Individual Dose ◽  
Protection Measures ◽  
Measurement Results ◽  
Individual Dosimetry ◽  
Dose Measurements ◽  
Self Protection

Measurement of individual radiation dose is crucial for planning protective measures after nuclear accidents. The purpose of this article is to explain the various initiatives taken after the TEPCO Fukushima Daiichi Nuclear Power Plant accident, including the D-shuttle project wherein residents from affected areas wore a personal dosimeter to measure their own external exposure. The experience in Fukushima revealed several issues such as gaining residents’ trust and ensuring appropriate communication of the measured data. The D-shuttle project also revealed that obtaining individual dose measurement data had 2 purposes, as the information obtained was to be utilized by the residents for self-protection and by the authorities for deriving the dose distribution of the population to aid in designing large-scale protection measures. The lessons learned are that both the residents and the authorities need to understand and share the meaning of individual dose measurements and the measurement results must be used with due respect for the residents’ privacy and other concerns.

Finding Optimal Model Parameters by Discrete Grid Search

2007 ◽  
pp. 120-127 ◽  
Author(s):  
Álvaro Barbero Jiménez ◽  
Jorge López Lázaro ◽  
José R. Dorronsoro
Keyword(s):  
Model Parameters ◽  
Grid Search ◽  
Optimal Model ◽  
Discrete Grid

scholarly journals Optimal Strategies for Dengue Prevention and Control during Daily Commuting between Two Residential Areas

Processes ◽  
2019 ◽  
Vol 7 (4) ◽  
pp. 197 ◽  
Author(s):  
Daniel Lasluisa ◽  
Edwin Barrios ◽  
Olga Vasilieva
Keyword(s):  
Optimal Strategies ◽  
Control Measures ◽  
Transmission Model ◽  
Human Populations ◽  
Personal Protection ◽  
Residential Areas ◽  
Protection Measures ◽  
Infected People ◽  
Mosquito Nets ◽  
Dengue Prevention

: In this paper, we report an application for the mathematical theory of dynamic optimization for design of optimal strategies that account for daily commuting of human residents, aiming to reduce vector-borne infections (dengue) among human populations. Our analysis is based on a two-patch dengue transmission model amended with control variables that represent personal protection measures aimed at reduction of the number of contacts between mosquitoes and human hosts (e.g., the use of repellents, mosquito nets, or insecticide-treated clothing). As a result, we have proposed and numerically solved an optimal control problem to minimize the costs associated with the application of control measures, while also minimizing the total number of dengue-infected people in both residential areas. Our principal goal was to identify an optimal strategy for personal protection that renders the maximal number of averted human infections per unit of invested cost, and this goal has been accomplished on the grounds of cost-effectiveness analysis.

scholarly journals Micro Sand Engine Beach Stabilization Strategy at Puerto Morelos, Mexico

2020 ◽  
Vol 8 (4) ◽  
pp. 247 ◽  
Author(s):  
Mireille Escudero ◽  
Edgar Mendoza ◽  
Rodolfo Silva
Keyword(s):  
Small Scale ◽  
Coastal Protection ◽  
Protection Measure ◽  
Morphological Response ◽  
Protection Measures ◽  
Small Bell ◽  
Waves And Currents ◽  
Maintenance Work ◽  
Negative Impacts ◽  
The Waves

In the last decade, innovative beach nourishment strategies have been developed, driven by the increased worldwide interest in environmentally friendly coastal protection measures. In this context, the massive nourishment project of the Netherlands, known as Sand Engine, begun in 2011, has been hailed as a successful means of beach protection. Continuous monitoring, field campaigns, and numerical modeling have shown that the great volume of sand deployed is gradually transported by the waves and currents along the coastline, avoiding the need for repeated invasive, small scale beach replenishments. A very small, bell-shaped Sand Engine was designed to protect the beachfront at a tourist resort near Puerto Morelos, Mexico. To estimate the morphological response of the beach and the functioning of the micro Sand Engine as a sand reservoir, XBeach numerical modelling was applied to the project. The micro Sand Engine is seen to be a sustainable and eco-friendly coastal protection measure, especially applicable when a large nourishment project is not viable. Maintenance work for the nourishment is cost and time effective, and any negative impacts to sensitive ecosystems nearby can be detected and controlled quickly.

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