scholarly journals Modeling the Spread of COVID-19 in Enclosed Spaces

2021 ◽  
Vol 26 (4) ◽  
pp. 79
Author(s):  
Matthew David Gaddis ◽  
Valipuram S. Manoranjan
Keyword(s):  
Sensitivity Analysis ◽  
Age Groups ◽  
Infection Rates ◽  
Production Rates ◽  
Seir Model ◽  
Open Environments ◽  
Age Structured ◽  
Enclosed Space

SEIR models are typically conjured for populations in open environments; however, there seems to be a lack of these types of models that deal with infection rates amongst enclosed spaces. We have also seen certain age groups struggle to deal with COVID-19 more than others, and to this end, we have constructed an age-structured SEIR model that incorporates the Gammaitoni–Nucci model, which is used for infective material in an enclosed space with ventilation. We apply some sensitivity analysis to better understand which parameters have the biggest impact on overall infection rates, as well as create a realistic scenario in which we apply our model to see the comparison in sickness rates amongst four different age groups with different ventilation filtration systems (UVGI, HEPA) and differing quanta production rates.

scholarly journals An age-structured SEIR model for COVID-19 incidence in Dublin, Ireland with framework for evaluating health intervention cost

PLoS ONE ◽  
2021 ◽  
Vol 16 (12) ◽  
pp. e0260632
Author(s):  
Fatima-Zahra Jaouimaa ◽  
Daniel Dempsey ◽  
Suzanne Van Osch ◽  
Stephen Kinsella ◽  
Kevin Burke ◽  
...  
Keyword(s):  
Social Interactions ◽  
Strong Association ◽  
Age Groups ◽  
Incidence Rates ◽  
Age Group ◽  
Seir Model ◽  
Age Cohorts ◽  
Intervention Cost ◽  
Age Structured ◽  
Predictive Approaches

Strategies adopted globally to mitigate the threat of COVID–19 have primarily involved lockdown measures with substantial economic and social costs with varying degrees of success. Morbidity patterns of COVID–19 variants have a strong association with age, while restrictive lockdown measures have association with negative mental health outcomes in some age groups. Reduced economic prospects may also afflict some age cohorts more than others. Motivated by this, we propose a model to describe COVID–19 community spread incorporating the role of age-specific social interactions. Through a flexible parameterisation of an age-structured deterministic Susceptible Exposed Infectious Removed (SEIR) model, we provide a means for characterising different forms of lockdown which may impact specific age groups differently. Social interactions are represented through age group to age group contact matrices, which can be trained using available data and are thus locally adapted. This framework is easy to interpret and suitable for describing counterfactual scenarios, which could assist policy makers with regard to minimising morbidity balanced with the costs of prospective suppression strategies. Our work originates from an Irish context and we use disease monitoring data from February 29th 2020 to January 31st 2021 gathered by Irish governmental agencies. We demonstrate how Irish lockdown scenarios can be constructed using the proposed model formulation and show results of retrospective fitting to incidence rates and forward planning with relevant “what if / instead of” lockdown counterfactuals. Uncertainty quantification for the predictive approaches is described. Our formulation is agnostic to a specific locale, in that lockdown strategies in other regions can be straightforwardly encoded using this model.

scholarly journals The signature features of COVID-19 pandemic in a hybrid mathematical model - implications for optimal work-school lockdown policy

2020 ◽  
Author(s):  
Teddy Lazebnik ◽  
Svetlana Bunimovich-Mendrazitsky
Keyword(s):  
Mathematical Model ◽  
Social Life ◽  
Reproduction Number ◽  
Age Groups ◽  
Time Of Day ◽  
Effective Vaccine ◽  
Infection Rates ◽  
Time Problem ◽  
School Day ◽  
Age Structured

AbstractBackgroundThe coronavirus disease 2019 (COVID-19) first identified in China, spreads rapidly across the globe and is considered the fastest moving pandemic in history. The new disease has challenged policymakers and scientists on key issues such as the magnitude of the first-time problem, the susceptibility of the population, the severity of the disease, and its symptoms. Most countries have adopted “lockdown” policies to reduce the spatial spread of COVID-19, but they have damaged the economic and moral fabric of society. Timely action to prevent the spread of the virus is critical, and mathematical modeling in non-pharmaceutical intervention (NPI) policy management has proven to be a major weapon in this fight due to the lack of an effective COVID-19 vaccine.MethodsWe present a new hybrid model for COVID-19 dynamics using both an age-structured mathematical model and spatio-temporal model in silico, analyzing the data of COVID-19 in Israel. The age-structured mathematical model is based on SIRD two age-class model. The spatial model examines a circle of day and night (with one-hour resolution) and three main locations (work / school or home) for every individual.ResultsWe determine mathematically the basic reproduction number R0 via the next-generation matrix based on Markov chain theory. Then, we analyze the stability of the equilibria and the effects of the significant differences in infection rates between children and adults. Using the hybrid model, we have introduced a method for estimating the reproduction number of an epidemic in real time from the data of daily notification of cases. The results of the proposed model are confirmed by the Israeli Lockdown experience with a mean square error of 0.205 over two weeks. The model was able to predict changes in R0 by opening schools on September 1, 2020, resulting in R0 = 2.2, which entailed a month’s quarantine of all areas of life. According to the model, by extending the school day to 9 hours, and assuming that children and adults go to school and work every day (except weekends), we get a significant reduction in R0 of 1.45. Finally, model-based analytical-numerical results are obtained and displayed in graphical profiles.ConclusionsThe use of mathematical models promises to reduce the uncertainty in the choice of “Lockdown” policies. Our unique use of contact details from 2 classes (children and adults), the interaction of populations depending on the time of day (the cycle of day and night), and several physical locations, allowed a new look at the differential dynamics of the spread and control of infection. Using knowledge about how the length of the work and school day affects the dynamics of the spread of the disease can be useful for improving control programs, mitigation, and policy.Author summaryEverybody in the modern world understands today that the pandemics threat is not less dangerous than the wars. COVID-19 showed us that pandemics effects the economies of all the countries over the world brings to a total lockdown of social life and enormous mortality. There was no effective vaccine/treatment, to stop the spread of COVID-19 and, therefore, policymakers have taken unprecedented measures, including quarantines, public health measures, travel bans, and others, without knowing in advance the effect of these restrictions.In this study, we develop a mathematical model of the pandemic spread taking into account the different dynamics of the disease in two age groups of children and adults. Using this model we succeeded to simulate the COVID-19 spread in Israel. The current study accurately predicts the effect of the work/school lockdown on the outbreaks. We have proven that by keeping schools open and increasing the school day to 8-9 hours, infection rates are reduced. Our results also show that if at least half of the adult population is a lockdown, the effect of children’s isolation on the infection rate is small, indicating the importance of multiple age groups of the population in the selection of restrictions.

scholarly journals ASSESSING VACCINATION STRATEGIES FOR THE COVID-19 EPIDEMIC IN MINAS GERAIS (BRAZIL)

2021 ◽  
Author(s):  
Marcelo Marchesin ◽  
Mehran Sabeti
Keyword(s):  
Age Groups ◽  
The Elderly ◽  
Minas Gerais ◽  
Elderly Group ◽  
Age Group ◽  
Seir Model ◽  
Current Strategy ◽  
Vaccination Strategies ◽  
Brazilian State ◽  
Age Structured

AbstractIn this work we analyze the effectiveness of vaccination strategies for the COVID-19 epidemic in the Brazilian state of Minas Gerais. Firstly we study the effectiveness of general vaccination in the decreasing of the number of infected individuals using a traditional non structured SEIR model. Secondly we consider an age-structured SEIR model with 3 age groups (youngster, adult and elderly) and we analyze the current strategy in the Brazilian state of Minas Gerais, of focusing the vaccination on the elderly group. We conclude by showing this strategy to be mistaken and that a vaccination focusing on the age group of the adults would be much more efficient in decreasing the total number of infected individuals.

POTENTIAL YIELD OF A ROCK SHRIMP STOCK, SICYONIA PENICILLATA IN THE NORTHERN GULF OF CALIFORNIA

Crustaceana ◽  
1999 ◽  
Vol 72 (6) ◽  
pp. 581-590 ◽  
Author(s):  
Juana Lopez-Martinez ◽  
Edgar Alcantara-Razo ◽  
Sergio Hernandez-Vazquez ◽  
Ernesto Chavez
Keyword(s):  
Gulf Of California ◽  
Age Groups ◽  
Potential Yield ◽  
Natural Oscillations ◽  
Recruitment Pattern ◽  
Stock Recruitment ◽  
Age Structured ◽  
Stochastic Recruitment ◽  
Age Structured Model ◽  
Compensatory Effect

AbstractA stock of rock shrimp Sicyonia penicillata was assessed in a fishery recently opened at Bahoa Kino, Sonora, Mexico. An age-structured model with stochastic recruitment was developed, which considers growth rate, natural mortality, and fishing mortality by age. Age groups were followed year by year with a stock-recruitment Ricker function where the seasonal recruitment pattern was defined as well. Simulations might be interpreted as showing a stable population with four year cycles, reflecting a density-dependent process. In 1996, fishing intensity had an apparent compensatory effect on the stock, decreasing the amplitude of natural oscillations and maintaining the stock at a biomass level similar to the size observed in a condition of no exploitation. The stock was found currently underexploited. As a result of the seasonal accessibility and the age of first-catch fishing (adult shrimp), the stock might be capable to withstand high fishing pressure without being overexploited. Se evaluo una poblacion de camaron de roca Sicyonia penicillata, de una pesqueroa recientemente abierta en Bahoa Kino, Sonora, Mexico. Se desarrollo un modelo basado en la estructura por edades que considera reclutamiento estocastico, tasa de crecimiento, mortalidad natural y mortalidad por pesca por grupo de edad. Estos grupos de edad fueron determinados ano tras ano mediante la funcion de reclutamiento de Ricker, en los que tambien se definio el patron estacional de reclutamiento. Las simulaciones muestran una poblacion estable con ciclos de cuatro anos, que indican un proceso de densodependencia. En 1996, la intensidad de pesca tuvo un efecto compensatorio sobre la poblacion, reduciendo la amplitud de las oscilaciones naturales y manteniendo al stock en un nivel de biomasa similar al observado en la condicion sin explotacion. Se encontro que el recurso esta subexplotado. Como resultado de la accesibilidad estacional y de que la edad de primera captura corresponde a camaron adulto, el recurso soporta alta presion de pesca sin dar evidencias de sobreexplotacion.

scholarly journals Mathematical Models for Assessing Vaccination Scenarios in Several Provinces in Indonesia

2020 ◽  
Author(s):  
N. Nuraini ◽  
K. Khairudin ◽  
P. Hadisoemarto ◽  
H. Susanto ◽  
A. Hasan ◽  
...  
Keyword(s):  
Mathematical Models ◽  
Age Groups ◽  
Transmission Model ◽  
West Java ◽  
Dynamic Transmission Model ◽  
Simulation Results ◽  
Age Structured

AbstractTo mitigate more casualties from the COVID-19 outbreak, this study assessed optimal vaccination scenarios, considering some existing healthcare conditions and some assumptions, by developing SIQRD (Susceptible-Infected-Quarantine-Recovery-Death) models for Jakarta, West Java, and Banten, in Indonesia. The models included an age-structured dynamic transmission model that naturally could give different treatments among age groups of population. The simulation results show that the timing and period’s length of the vaccination should be well planned and prioritizing particular age groups will give significant impact on the total number of casualties.

scholarly journals The effect of age and study duration on the relationship between ‘clustering’ of DNA fingerprint patterns and the proportion of tuberculosis disease attributable to recent transmission

2001 ◽  
Vol 126 (1) ◽  
pp. 43-62 ◽  
Author(s):  
E. VYNNYCKY ◽  
N. NAGELKERKE ◽  
M. W. BORGDORFF ◽  
D. VAN SOOLINGEN ◽  
J. D. A. VAN EMBDEN ◽  
...  
Keyword(s):  
Age Groups ◽  
Dna Fingerprint ◽  
Older Individuals ◽  
Study Duration ◽  
Time Period ◽  
Recent Transmission ◽  
Dependent Risks ◽  
Age Structured ◽  
Age Structured Model ◽  
The Relationship

Though it is recognized that the extent of ‘clustering’ of isolates from tuberculosis cases in a given population is related to the amount of disease attributable to recent transmission, the relationship between the two statistics is poorly understood. Given age-dependent risks of disease and the fact that a long study (e.g. spanning several years) is more likely to identify transmission-linked cases than a shorter study, both measures, and thus the relationship between them, probably depend strongly on the ages of the cases ascertained and study duration. The contribution of these factors is explored in this paper using an age-structured model which describes the introduction and transmission of M. tuberculosis strains with different DNA fingerprint patterns in The Netherlands during this century, assuming that the number of individuals contacted by each case varies between cases and that DNA fingerprint patterns change over time through random mutations, as observed in several studies.Model predictions of clustering in different age groups and over different time periods between 1993 and 1997 compare well against those observed. According to the model, the proportion of young cases with onset in a given time period who were ‘clustered’ underestimated the proportion of disease attributable to recent transmission in this age group (by up to 25% in males); for older individuals, clustering overestimated this proportion. These under- and overestimates decreased and increased respectively as the time period over which the cases were ascertained increased. These results have important implications for the interpretation of estimates of the proportion of disease attributable to recent transmission, based on ‘clustering’ statistics, as are being derived from studies of the molecular epidemiology of tuberculosis in many populations.

scholarly journals The demographic dividend is more than an education dividend

2020 ◽  
Vol 117 (42) ◽  
pp. 25982-25984
Author(s):  
Rainer Kotschy ◽  
Patricio Suarez Urtaza ◽  
Uwe Sunde
Keyword(s):  
Human Capital ◽  
Age Structure ◽  
Age Distribution ◽  
Age Groups ◽  
Demographic Dividend ◽  
Positive Growth ◽  
Working Age ◽  
Age Structured ◽  
Positive Effect ◽  
Effect Of Age

The demographic dividend has long been viewed as an important factor for economic development and provided a rationale for policies aiming at a more balanced age structure through birth control and family planning. Assessing the relative importance of age structure and increases in human capital, recent work has argued that the demographic dividend is related to education and has suggested a dominance of improving education over age structure. Here we reconsider the empirical relevance of shifts in the age distribution for development for a panel of 159 countries over the period 1950 to 2015. Based on a flexible model of age-structured human capital endowments, the results document important interactions between age structure and human capital endowments, suggesting that arguments of clear dominance of education over age structure are unwarranted and lead to potentially misleading policy conclusions. An increase in the working-age population share has a strong and significant positive effect on growth, even conditional on human capital, in line with the conventional notion of a demographic dividend. An increase in human capital only has positive growth effects if combined with a suitable age structure. An increasing share of the most productive age groups has an additional positive effect on economic performance. Finally, the results show considerable heterogeneity in the effect of age structure and human capital for different levels of development. Successful policies for sustainable development should take this heterogeneity into account to avoid detrimental implications of a unidimensional focus on human capital without accounting for demography.

Spatial Mapping of HIV Infection by Means of Mixture Models

2015 ◽  
Vol 781 ◽  
pp. 599-603 ◽  
Author(s):  
Chukiat Viwatwongkasam ◽  
Watcharawan Gunngam ◽  
Pichitpong Soontornpipit
Keyword(s):  
Hiv Infection ◽  
Mixture Models ◽  
Age Groups ◽  
National Standard ◽  
Infection Rates ◽  
Health Security ◽  
Health Resource Allocation ◽  
Standard Population ◽  
Risk Areas ◽  
Study Population

Geographical distribution of HIV infection has an important role to serve the policy and the health resource allocation. A standardized infection ratio (SIR) is a measure of interest for identifying HIV infected on a map while controlling age-confounder by applying age-specific infection rates of a standard population to the study population. Mixture models of Poisson distributions allowing for heterogeneity using the nonparametric maximum likelihood (NPML) estimators were proposed to classify SIRs into the area clusters. Surveillance data of the number of HIV cases infected overall the country, classified by provinces and age groups, collected by the National Health Security Office (NHSO) were adopted during 2008 to 2013 in Thailand. The results indicated that in 2013 there were 18,081 persons infected with HIV among 623,265 people scrutinized with blood test (about 2.90 per 100). After applying the standard age-specific infection rates with the past five years 2008-2012 of HIV infection overall the country to each province, the SIR for each province varied widely around the mean 0.83 (SD =0.51) and this reported a 17% decrease in SIR Thailand 2013 compared with the national standard in 2008-2012. Mixture model has provided 5 clusters of high risk areas. The provinces with the five highest SIRs were Nongbualamphu (3.13), Chumphon (2.26), Samutprakan (2.09), Udonthani (2.04), Pathumthani (1.63). Finally, the mixture program for analysis of data is available on request.

scholarly journals Seroprevalence of Toxoplasma gondii in Dairy Cattle with Reproductive Problems in Sudan

2013 ◽  
Vol 2013 ◽  
pp. 1-4 ◽  
Author(s):  
Abdelghafar M. Elfahal ◽  
Amira M. Elhassan ◽  
Mohammed O. Hussien ◽  
Khalid A. Enan ◽  
Azza B. Musa ◽  
...  
Keyword(s):  
Toxoplasma Gondii ◽  
Dairy Cattle ◽  
Age Groups ◽  
Parasitic Infections ◽  
Age Group ◽  
Infection Rates ◽  
Herd Level ◽  
Individual Level ◽  
Reproductive Disease ◽  
One Year

Toxoplasmosis, caused by Toxoplasma gondii, is one of the most common parasitic infections of humans and other warm-blooded animals in most parts of the world. The disease is common among sheep and goats and it is recognized as one of the major causes of reproductive failure in these animals. Cattle, on the other hand, can be infected, but abortion or perinatal mortality has not been recorded. This survey was carried out to study the prevalence of this disease in cattle in Khartoum and Gazira States (Sudan). 181 sera samples collected from dairy cattle with reproductive problems were assayed for antibodies to T. gondii by ELISA. The prevalence rate of T. gondii antibodies in cattle at herd level was 44.8% (13/29). Herd level infection rates were 50% and 33.3% in Khartoum and Gazira States, respectively. The overall prevalence of T. gondii at individual level in both states was 13.3% (24/181). The prevalence was 12.7% (17/134), was 14.9% (7/47) in Khartoum and Gazira State, respectively. There was significantly higher (P<0.05) prevalence of T. gondii antibodies in the age group less than one year old (36.4%) than in other age groups and in males (30.8%) than in females (11.9%) while no significant relationship was discerned regarding breed, location, season, or signs of reproductive disease.

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