scholarly journals A modified age-structured SIR model for COVID-19 type viruses

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Vishaal Ram ◽  
Laura P. Schaposnik
Keyword(s):  
Mortality Rate ◽  
Age Distribution ◽  
Social Contact ◽  
Sir Model ◽  
Disease Spread ◽  
Population Parameters ◽  
Specific Contact ◽  
Treatment Measures ◽  
Age Structured ◽  
Varying Population

AbstractWe present a modified age-structured SIR model based on known patterns of social contact and distancing measures within Washington, USA. We find that population age-distribution has a significant effect on disease spread and mortality rate, and contribute to the efficacy of age-specific contact and treatment measures. We consider the effect of relaxing restrictions across less vulnerable age-brackets, comparing results across selected groups of varying population parameters. Moreover, we analyze the mitigating effects of vaccinations and examine the effectiveness of age-targeted distributions. Lastly, we explore how our model can applied to other states to reflect social-distancing policy based on different parameters and metrics.

scholarly journals Quantifying social contact patterns in Minnesota during Stay-at-Home social distancing order

2021 ◽  
Author(s):  
Audrey M Dorelien ◽  
Narmada Venkateswaran ◽  
Jiuchen Deng ◽  
Kelly Searle ◽  
Eva Enns ◽  
...  
Keyword(s):  
Negative Binomial ◽  
Social Contact ◽  
Negative Binomial Regression ◽  
Risk Groups ◽  
Social Distancing ◽  
Contact Patterns ◽  
Specific Contact ◽  
Contact Data ◽  
Age Structured ◽  
At Home

SARS-CoV-2 is primarily transmitted through person-to-person contacts. It is important to collect information on age-specific contact patterns because SARS-CoV-2 susceptibility, transmission, and morbidity vary by age. To reduce risk of infection, social distancing measures have been implemented. Social contact data, which identify who has contact with whom especially by age and place are needed to identify high-risk groups and serve to inform the design of non-pharmaceutical interventions. We estimated and used negative binomial regression to compare the number of daily contacts during the first wave (April-May 2020) of the Minnesota Social Contact Study, based on respondents age, gender, race/ethnicity, region, and other demographic characteristics. We used information on age and location of contacts to generate age-structured contact matrices. Finally, we compared the age-structured contact matrices during the stay-at-home order to pre-pandemic matrices. During the state-wide stay-home order, the mean daily number of contacts was 5.6. We found significant variation in contacts by age, gender, race, and region. Adults between 40 and 50 years had the highest number of contacts. Respondents in Black households had 2.1 more contacts than respondent in White households, while respondents in Asian or Pacific Islander households had approximately the same number of contacts as respondent in White households. Respondents in Hispanic households had approximately two fewer contacts compared to White households. Most contacts were with other individuals in the same age group. Compared to the pre-pandemic period, the biggest declines occurred in contacts between children, and contacts between those over 60 with those below 60.

scholarly journals Age-structured SIR model and resource growth dynamics: A preliminary COVID-19 study

2020 ◽  
Author(s):  
S. G. Babajanyan ◽  
Kang Hao Cheong
Keyword(s):  
Growth Dynamics ◽  
Sir Model ◽  
Disease Outbreak ◽  
Disease Spread ◽  
Logistic Growth ◽  
Economic Implications ◽  
Spread Dynamics ◽  
Resource Dynamics ◽  
Age Structured ◽  
Different Response

In this paper, we discuss three different response strategies to a disease outbreak and their economic implications in an age-structured population. We have utilized the classical age structured SIR-model, thus assuming that recovered people will not be infected again. Available resource dynamics is governed by the well-known logistic growth model, in which the reproduction coefficient depends on the disease outbreak spreading dynamics. We further investigate the feedback interaction of the disease spread dynamics and resource growth dynamics with the premise that the quality of treatment depends on the current economic situation. The very inclusion of mortality rates and economic considerations in the same model may be incongruous under certain positions, but in this model, we take a 'realpolitik' approach by exploring all of these factors together as it is done in reality.

scholarly journals Cohort-based Smoothing Methods for Age-specific Contact Rates

2018 ◽  
Author(s):  
Yannick Vandendijck ◽  
Carlo G. Camarda ◽  
Niel Hens
Keyword(s):  
Disease Transmission ◽  
Age Distribution ◽  
Social Contact ◽  
Population Based ◽  
Smoothing Methods ◽  
Transmission Parameters ◽  
Contact Rates ◽  
The Social ◽  
Specific Contact ◽  
Contact Data

AbstractThe use of social contact rates is widespread in infectious disease modelling, since it is known that they provide proxies of crucial determinants of epidemiological and disease transmission parameters. Information on social contact rates can, for example, be obtained from a population-based contact diary survey, such as the POLYMOD study. Estimation of age-specific contact rates from these studies is often done using bivariate smoothing techniques. Typically, smoothing is done in the dimensions of the respondent’s and contact’s age. In this paper, we introduce a smoothing constrained approach - taking into account the reciprocal nature of contacts - where the contact rates are assumed smooth from a cohort perspective as well as from the age distribution of contacts. This is achieved by smoothing over the diagonal components (including all subdiagonals) of the social contact matrix. This approach is supported by the fact that people age with time and thus contact rates should vary smoothly by cohorts. Two approaches that allow for smoothing of social contact data over cohorts are proposed: (1) reordening of the diagonal components of the social contact rate matrix; and (2) reordening of the penalty matrix associated with the diagonal components. Parameter estimation is done using constrained penalized iterative reweighted least squares. A simulation study is presented to compare methods. The proposed methods are illustrated on the Belgian POLYMOD data of 2006.

scholarly journals SIR Model for Dengue Disease with Effect of Dengue Vaccination

2018 ◽  
Vol 2018 ◽  
pp. 1-14 ◽  
Author(s):  
Pratchaya Chanprasopchai ◽  
I. Ming Tang ◽  
Puntani Pongsumpun
Keyword(s):  
Mathematical Model ◽  
Mortality Rate ◽  
Dengue Virus ◽  
Numerical Solutions ◽  
Specific Treatment ◽  
Sir Model ◽  
Dengue Vaccine ◽  
Dengue Disease ◽  
Modelling Methods

The dengue disease is caused by dengue virus, and there is no specific treatment. The medical care by experienced physicians and nurses will save life and will lower the mortality rate. A dengue vaccine to control the disease is available in Thailand since late 2016. A mathematical model would be an important way to analyze the effects of the vaccination on the transmission of the disease. We have formulated an SIR (susceptible-infected-recovered) model of the transmission of the disease which includes the effect of vaccination and used standard dynamical modelling methods to analyze the effects. The equilibrium states and their stabilities are investigated. The trajectories of the numerical solutions plotted into the 2D planes and 3D spaces are presented. The main contribution is determining the role of dengue vaccination in the model. From the analysis, we find that there is a significant reduction in the total hospitalization time needed to treat the illness.

scholarly journals DECREASING PREVALENCE OF THE ACUTE/SUBACUTE CLINICAL FORM OF PARACOCCIDIOIDOMYCOSIS IN MATO GROSSO DO SUL STATE, BRAZIL

2014 ◽  
Vol 56 (2) ◽  
pp. 121-125 ◽  
Author(s):  
Larissa Rodrigues Fabris ◽  
Úrsulla Vilella Andrade ◽  
Aline Ferreira Dos Santos ◽  
Ana Paula da Costa Marques ◽  
Sandra Maria do Valle Leone de Oliveira ◽  
...  
Keyword(s):  
Mortality Rate ◽  
Age Distribution ◽  
Epidemiological Data ◽  
Infection Prevalence ◽  
Age Group ◽  
Clinical Form ◽  
Mato Grosso ◽  
Co Morbidity ◽  
Mato Grosso Do Sul ◽  
Overall Mortality

With the objective to evaluate the behavior of paracoccidioidomycosis in the last three decades, clinical and epidemiological data of 595 patients admitted to clinical services of the Federal University of Mato Grosso do Sul from 1980 to 2009 were investigated. Gender, age distribution, clinical form, comorbidity with tuberculosis or AIDS, and mortality were compared by decades of clinical admission. It was shown that during the three decades there was a decrease in women percentage, and the same manner occurred a reduction in participants in the age group of 20 to 39 years. Moreover, the acute/subacute forms have been diminished in the period. These fluctuations are closely related and can be simultaneously analyzed. Increased AIDS co-infection prevalence from the first to the second decade was also revealed, coinciding with the appearance of the retroviral epidemic and stabilizing during the third decade. No change in the tuberculosis co-infection rate was observed (overall = 6.9%). It reinforces the importance of this co-morbidity. The overall mortality rate remained steady at 6.7%, not varying significantly from one decade to another. The persistent mortality rate calls attention to the importance of this neglected disease.

scholarly journals Household members do not contact each other at random: implications for infectious disease modelling

2018 ◽  
Vol 285 (1893) ◽  
pp. 20182201 ◽  
Author(s):  
Nele Goeyvaerts ◽  
Eva Santermans ◽  
Gail Potter ◽  
Andrea Torneri ◽  
Kim Van Kerckhove ◽  
...  
Keyword(s):  
Infectious Disease ◽  
Social Contact ◽  
Household Contact ◽  
Epidemic Models ◽  
Disease Spread ◽  
Contact Density ◽  
Contact Networks ◽  
Household Transmission ◽  
Household Members ◽  
Contact Survey

Airborne infectious diseases such as influenza are primarily transmitted from human to human by means of social contacts, and thus easily spread within households. Epidemic models, used to gain insight into infectious disease spread and control, typically rely on the assumption of random mixing within households. Until now, there has been no direct empirical evidence to support this assumption. Here, we present the first social contact survey specifically designed to study contact networks within households. The survey was conducted in Belgium (Flanders and Brussels) from 2010 to 2011. We analysed data from 318 households totalling 1266 individuals with household sizes ranging from two to seven members. Exponential-family random graph models (ERGMs) were fitted to the within-household contact networks to reveal the processes driving contact between household members, both on weekdays and weekends. The ERGMs showed a high degree of clustering and, specifically on weekdays, decreasing connectedness with increasing household size. Furthermore, we found that the odds of a contact between older siblings and between father and child are smaller than for any other pair. The epidemic simulation results suggest that within-household contact density is the main driver of differences in epidemic spread between complete and empirical-based household contact networks. The homogeneous mixing assumption may therefore be an adequate characterization of the within-household contact structure for the purpose of epidemic simulations. However, ignoring the contact density when inferring based on an epidemic model will result in biased estimates of within-household transmission rates. Further research regarding the implementation of within-household contact networks in epidemic models is necessary.

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.

Age, growth and the potential for growth overfishing of spot (Leiostomus xanthurus) from the Chesapeake Bay, eastern USA

2004 ◽  
Vol 55 (6) ◽  
pp. 553 ◽  
Author(s):  
Kevin R. Piner ◽  
Cynthia M. Jones
Keyword(s):  
Mortality Rate ◽  
Chesapeake Bay ◽  
Total Mortality ◽  
First Year ◽  
Leiostomus Xanthurus ◽  
Vital Rates ◽  
Population Parameters ◽  
Lack Of Information ◽  
Eastern Usa ◽  
Management Advice

Spot (Leiostomus xanthurus) are a popular commercial and sport fish in the Chesapeake Bay region (USA), but have not been managed with age-based models because of a lack of information on vital rates. This study determined that transversely sectioned otoliths were the most appropriate structure to age spot, and subsequently used those ages to estimate biological parameters and evaluate the potential for growth overfishing. Because spot are short-lived, this study explored estimating population parameters using both whole annulus counts and fractional ages. Although fractional ages may be more realistic, parameters estimated using fractions of a year should be interpreted with caution. Growth of spot was rapid (84% of length attained in the first year), the natural mortality rate was high (59% year−1), and the total mortality rate (natural + fishing) was very high (80–94% year−1). Spot maximised cohort biomass early in life (≈1 year) and were relatively impervious to growth overfishing. This study illustrates the difficulty in providing management advice for species that maximise cohort biomass about the same time as their first potential spawning event. This study also documents that high exploitation rates and size selective fishing gear probably affect estimates of population parameters.

An Application of Computers to the Estimation of Exploited Populations

1969 ◽  
Vol 26 (1) ◽  
pp. 179-189
Author(s):  
K. Radway Allen
Keyword(s):  
Mortality Rate ◽  
Age Distribution ◽  
The Other ◽  
Population Estimates ◽  
Distribution Data ◽  
Natural Mortality ◽  
Computer Programme ◽  
Total Catch ◽  
The Third

This paper describes a computer programme for the estimation of the size of exploited populations by methods described in Allen (1966, J. Fish. Res. Bd. Canada 23: 1553–1574). Although these methods were originally developed for use on whale populations, they are applicable to any other populations where suitable data are available. The essential data are the total catch, the catch for a known amount of effort, and the age distribution of the catch, all for a series of years. An estimate of natural mortality rate is also required but population estimates may be obtained for up to 10 values of this parameter in a single computer run.The entire programme incorporates six subroutines, as well as the main controlling programme. One subroutine reads in the catch and effort data, a second reads in the age distribution data for each year and, if necessary, converts it according to a predetermined transformation from age expressed in terms of whale ear-plug laminations to age in years. The third subroutine estimates the rate of recruitment as the proportion of newly recruited animals in the catch for each year, using the method of Allen (1966). The other three subroutines derive population estimates, using the "q," modified DeLury, and actual and expected catch methods (Allen, 1966). As many sets of data as desired may be processed in a single computer run.

An analysis of variations in the age structure of Fasciola hepatica populations in sheep

Parasitology ◽  
1982 ◽  
Vol 84 (1) ◽  
pp. 49-61 ◽  
Author(s):  
Gary Smith
Keyword(s):  
Mathematical Model ◽  
Mortality Rate ◽  
Age Structure ◽  
Distribution Curve ◽  
Fasciola Hepatica ◽  
Age Distribution ◽  
Parasite Population ◽  
Simple Mathematical Model ◽  
Age Classes

SUMMARYThe processes which govern the age structure of Fasciola hepatica populations in sheep were investigated by means of a simple mathematical model. The mortality of the metacercariae on the pasture was shown to be a factor of major importance. The mortality rate depends on the micro-climate that prevails at the pasture surface, and thus the age distribution curve of a population of flukes is also determined in part by the weather. This has important implications for the chemotherapy of fascioliasis: flukicides are not equally effective over the whole range of age-classes of parasite and so the factors which govern the age distribution curve of the parasite population within individual hosts ultimately determine the efficiency of chemotherapy.

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