scholarly journals Possible future waves of SARS-CoV-2 infection generated by variants of concern with a range of characteristics

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Louise Dyson ◽  
Edward M. Hill ◽  
Sam Moore ◽  
Jacob Curran-Sebastian ◽  
Michael J. Tildesley ◽  
...  
Keyword(s):  
Mathematical Models ◽  
Disease Severity ◽  
Immune Escape ◽  
Deterministic Model ◽  
Control Measures ◽  
Structured Model ◽  
Age Structured ◽  
Age Structured Model ◽  
Viral Reproduction ◽  
Importation Model

AbstractViral reproduction of SARS-CoV-2 provides opportunities for the acquisition of advantageous mutations, altering viral transmissibility, disease severity, and/or allowing escape from natural or vaccine-derived immunity. We use three mathematical models: a parsimonious deterministic model with homogeneous mixing; an age-structured model; and a stochastic importation model to investigate the effect of potential variants of concern (VOCs). Calibrating to the situation in England in May 2021, we find epidemiological trajectories for putative VOCs are wide-ranging and dependent on their transmissibility, immune escape capability, and the introduction timing of a postulated VOC-targeted vaccine. We demonstrate that a VOC with a substantial transmission advantage over resident variants, or with immune escape properties, can generate a wave of infections and hospitalisations comparable to the winter 2020-2021 wave. Moreover, a variant that is less transmissible, but shows partial immune-escape could provoke a wave of infection that would not be revealed until control measures are further relaxed.

scholarly journals Possible future waves of SARS-CoV-2 infection generated by variants of concern with a range of characteristics

2021 ◽  
Author(s):  
Louise Dyson ◽  
Edward M Hill ◽  
Sam Moore ◽  
Jacob Curran-Sebastian ◽  
Michael J Tildesley ◽  
...  
Keyword(s):  
Immune Escape ◽  
Deterministic Model ◽  
Control Measures ◽  
Transmission Model ◽  
Vaccination Rates ◽  
Infection Dynamics ◽  
Potential Impact ◽  
Age Structured ◽  
Ongoing Infection ◽  
Viral Reproduction

Ongoing infection with, and associated viral reproduction of, SARS-CoV-2 provides opportunities for the virus to acquire advantageous mutations, which may alter viral transmissibility and disease severity, and allow escape from natural or vaccine-derived immunity. The number of countries reporting Variants of Concern (VOCs) with such mutations continues to rise. Here, we investigate two scenarios for third waves of the COVID pandemic: one driven by increased transmissibility, and another driven by immune escape. We do this using three mathematical models: a parsimonious susceptible-latent-infectious-recovered (SEIR) deterministic model with homogeneous mixing, an age-structured SARS-CoV-2 transmission model and a stochastic importation model. We calibrated our models to the situation in England in May 2021, although the insights will generalise to other contexts. We therefore accurately captured infection dynamics and vaccination rates, and also used these to explore the potential impact of a putative new VOC-targeted vaccine. Epidemiological trajectories for putative VOCs are wide-ranging and heavily dependent on their transmissibility, immune escape capability, and the time at which a postulated VOC-targeted vaccine may be introduced. We demonstrate that a VOC with either a substantial transmission advantage over resident variants, or the ability to evade vaccine-derived and prior immunity, is expected to generate a wave of infections and hospitalisations comparable to those seen in the winter 2020-21 wave. Moreover, a variant that is less transmissible, but shows partial immune-escape could provoke a wave of infection that would not be revealed until control measures are further relaxed.

An Age-Structured Model of Fish Population Enhancement

2002 ◽  
pp. 376-394
Author(s):  
Richard Langton ◽  
James Lindholm ◽  
James Wilson ◽  
Sally Sherman
Keyword(s):  
Fish Population ◽  
Structured Model ◽  
Age Structured ◽  
Age Structured Model

scholarly journals Null Controllability of a Nonlinear Age Structured Model for a Two-Sex Population

2021 ◽  
Vol 2021 ◽  
pp. 1-20
Author(s):  
Amidou Traoré ◽  
Okana S. Sougué ◽  
Yacouba Simporé ◽  
Oumar Traoré
Keyword(s):  
Null Controllability ◽  
Auxiliary System ◽  
Time Interval ◽  
Observability Inequality ◽  
Controllability Problem ◽  
Structured Model ◽  
Male And Female ◽  
System A ◽  
Age Structured ◽  
Age Structured Model

This paper is devoted to study the null controllability properties of a nonlinear age and two-sex population dynamics structured model without spatial structure. Here, the nonlinearity and the couplage are at the birth level. In this work, we consider two cases of null controllability problem. The first problem is related to the extinction of male and female subpopulation density. The second case concerns the null controllability of male or female subpopulation individuals. In both cases, if A is the maximal age, a time interval of duration A after the extinction of males or females, one must get the total extinction of the population. Our method uses first an observability inequality related to the adjoint of an auxiliary system, a null controllability of the linear auxiliary system, and after Kakutani’s fixed-point theorem.

An age-structured model for erratic crappie fisheries

1998 ◽  
Vol 107 (2-3) ◽  
pp. 289-303 ◽  
Author(s):  
Micheal S Allen ◽  
Leandro E Miranda
Keyword(s):  
Structured Model ◽  
Age Structured ◽  
Age Structured Model
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