659 research outputs found
An Sveir Model for Assessing Potential Impact of an Imperfect Anti-SARS Vaccine
The control of severe acute respiratory syndrome (SARS), a fatal contagious viral disease that spread to over 32 countries in 2003, was based on quarantine of latently infected individuals and isolation of individuals with clinical symptoms of SARS. Owing to the recent ongoing clinical trials of some candidate anti-SARS vaccines, this study aims to assess, via mathematical modelling, the potential impact of a SARS vaccine, assumed to be imperfect, in curtailing future outbreaks. A relatively simple deterministic model is designed for this purpose. It is shown, using Lyapunov function theory and the theory of compound matrices, that the dynamics of the model are determined by a certain threshold quantity known as the control reproduction number (Rv). If Rv ≤ 1, the disease will be eliminated from the community; whereas an epidemic occurs if Rv \u3e 1. This study further shows that an imperfect SARS vaccine with infection-blocking efficacy is always beneficial in reducing disease spread within the community, although its overall impact increases with increasing efficacy and coverage. In particular, it is shown that the fraction of individuals vaccinated at steady-state and vaccine efficacy play equal roles in reducing disease burden, and the vaccine must have efficacy of at least 75% to lead to effective control of SARS (assuming R0 = 4). Numerical simulations are used to explore the severity of outbreaks when Rv \u3e 1
Assessing potential insights of an imperfect testing strategy: Parameter estimation and practical identifiability using early COVID-19 data in India
A deterministic model with testing of infected individuals has been proposed
to investigate the potential consequences of the impact of testing strategy.
The model exhibits global dynamics concerning the disease-free and a unique
endemic equilibrium depending on the basic reproduction number when the
recruitment of infected individuals is zero; otherwise, the model does not have
a disease-free equilibrium, and disease never dies out in the community. Model
parameters have been estimated using the maximum likelihood method with respect
to the data of early COVID-19 outbreak in India. The practical identifiability
analysis shows that the model parameters are estimated uniquely. The
consequences of the testing rate for the weekly new cases of early COVID-19
data in India tell that if the testing rate is increased by 20% and 30% from
its baseline value, the weekly new cases at the peak are decreased by 37.63%
and 52.90%; and it also delayed the peak time by four and fourteen weeks,
respectively. Similar findings are obtained for the testing efficacy that if it
is increased by 12.67% from its baseline value, the weekly new cases at the
peak are decreased by 59.05% and delayed the peak by 15 weeks. Therefore, a
higher testing rate and efficacy reduce the disease burden by tumbling the new
cases, representing a real scenario. It is also obtained that the testing rate
and efficacy reduce the epidemic's severity by increasing the final size of the
susceptible population. The testing rate is found more significant if testing
efficacy is high. Global sensitivity analysis using partial rank correlation
coefficients (PRCCs) and Latin hypercube sampling (LHS) determine the key
parameters that must be targeted to worsen/contain the epidemic
最終感染規模に対する隔離の効果に関する個体群動態モデル
Tohoku University博士(情報科学)thesi
(R1507) Mathematical Modeling and Analysis of Seqiahr Model: Impact of Quarantine and Isolation on COVID-19
At the moment in time, an outbreak of COVID-19 is transmitting on from human to human. Different parts have different quality of life (e.g., India compared to Russia), which implies the impact varies in each part of the world. Although clinical vaccines are available to cure, the question is how to minimize the spread without considering the vaccine. In this paper, via a mathematical model, the transmission dynamics of novel coronavirus with quarantine and isolation facilities have been proposed. The examination of the proposed model is set in motion with the boundedness and positivity of the solution, sole disease-free equilibrium, and local stability. Then, the condition for the existence of sole endemic equilibrium and its local stability has established. In addition, the global stability of the endemic equilibrium for a special case has been investigated. Further, it has shown that the system undergoes a transcritical bifurcation. A threshold analysis has also performed to examine the effect of quarantine on transmission dynamics. Lastly, numerical simulations are giving hand support to theoretical results
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