scholarly journals Modeling COVID-19 with mean field evolutionary dynamics: Social distancing and seasonality

2021 ◽  
Vol 23 (5) ◽  
pp. 314-325
Author(s):  
Hao Gao ◽  
Wuchen Li ◽  
Miao Pan ◽  
Zhu Han ◽  
H. Vincent Poor
2020 ◽  
Vol 19 (12) ◽  
pp. 7825-7835
Author(s):  
Hao Gao ◽  
Wuchen Li ◽  
Reginald A. Banez ◽  
Zhu Han ◽  
H. Vincent Poor

Complexity ◽  
2017 ◽  
Vol 2017 ◽  
pp. 1-14 ◽  
Author(s):  
Giulio Cimini

We consider games of strategic substitutes and complements on networks and introduce two evolutionary dynamics in order to refine their multiplicity of equilibria. Within mean field, we find that for the best-shot game, taken as a representative example of strategic substitutes, replicator-like dynamics does not lead to Nash equilibria, whereas it leads to a unique equilibrium for complements, represented by a coordination game. On the other hand, when the dynamics becomes more cognitively demanding, predictions are always Nash equilibria: for the best-shot game we find a reduced set of equilibria with a definite value of the fraction of contributors, whereas, for the coordination game, symmetric equilibria arise only for low or high initial fractions of cooperators. We further extend our study by considering complex topologies through heterogeneous mean field and show that the nature of the selected equilibria does not change for the best-shot game. However, for coordination games, we reveal an important difference: on infinitely large scale-free networks, cooperative equilibria arise for any value of the incentive to cooperate. Our analytical results are confirmed by numerical simulations and open the question of whether there can be dynamics that consistently leads to stringent equilibria refinements for both classes of games.


2003 ◽  
Vol 5 (1) ◽  
pp. 47-58 ◽  
Author(s):  
L. A. Bach ◽  
D. J. T. Sumpter ◽  
J. Alsner ◽  
V. Loeschcke

Evolutionary game models of cellular interactions have shown that heterogeneity in the cellular genotypic composition is maintained through evolution to stable coexistence of growth-promoting and non-promoting cell types. We generalise these mean-field models and relax the assumption of perfect mixing of cells by instead implementing an individual-based model that includes the stochastic and spatial effects likely to occur in tumours. The scope for coexistence of genotypic strategies changed with the inclusion of explicit space and stochasticity. The spatial models show some interesting deviations from their mean-field counterparts, for example the possibility of altruistic (paracrine) cell strategies to thrive. Such effects can however, be highly sensitive to model implementation and the more realistic models with semi-synchronous and stochastic updating do not show evolution of altruism. We do find some important and consistent differences between the spatial and mean-field models, in particular that the parameter regime for coexistence of growth-promoting and nonpromoting cell types is narrowed. For certain parameters in the model a selective collapse of a generic growth promoter occurs, hence the evolutionary dynamics mimics observablein vivotumour phenomena such as (therapy induced) relapse behaviour. Our modelling approach differs from many of those previously applied in understanding growth of cancerous tumours in that it attempts to account for natural selection at a cellular level. This study thus points a new direction towards more plausible spatial tumour modelling and the understanding of cancerous growth.


2021 ◽  
Author(s):  
Martin Nowak ◽  
Gabriela Lobinska ◽  
Ady Pauzner ◽  
Arne Traulsen ◽  
Yitzhak Pilpel

Abstract The COVID-19 pandemic has led to an unprecedented global response in terms of social lockdown in order to slow the spread of the virus 1,2. Currently the greatest hope is based on world-wide vaccination3,4. The expectation is that social and economic activities can gradually resume as more and more people become vaccinated. Yet, a relaxation of social distancing that allows increased transmissibility, coupled with selection pressure due to vaccination, will likely lead to the emergence of vaccine resistance 5. Here we analyze the evolutionary dynamics of COVID-19 in the presence of dynamic lockdown and in response to vaccination. We use infection and vaccination data of 6 different countries (Israel, US, UK, Brazil, France and Germany) to assess the probability and timing for the wave of vaccine resistant mutant2. For slow vaccination rates, resistant mutants will appear inevitably even if strict lockdown is maintained. For fast vaccination rates (such as those used in Israel) the emergence of the mutant can be prevented if strict lockdown is maintained during vaccination. Our mathematical results provide quantitative guidelines for a combined vaccination and lockdown policy that minimizes the probability of emergence of vaccine resistance variants for current and future vaccination programs.


2013 ◽  
Vol 368 (1614) ◽  
pp. 20120207 ◽  
Author(s):  
Maciej F. Boni ◽  
Tran Dang Nguyen ◽  
Menno D. de Jong ◽  
H. Rogier van Doorn

More than 15 years after the first human cases of influenza A/H5N1 in Hong Kong, the world remains at risk for an H5N1 pandemic. Preparedness activities have focused on antiviral stockpiling and distribution, development of a human H5N1 vaccine, operationalizing screening and social distancing policies, and other non-pharmaceutical interventions. The planning of these interventions has been done in an attempt to lessen the cumulative mortality resulting from a hypothetical H5N1 pandemic. In this theoretical study, we consider the natural limitations on an H5N1 pandemic's mortality imposed by the virus' epidemiological–evolutionary constraints. Evolutionary theory dictates that pathogens should evolve to be relatively benign, depending on the magnitude of the correlation between a pathogen's virulence and its transmissibility. Because the case fatality of H5N1 infections in humans is currently 60 per cent, it is doubtful that the current viruses are close to their evolutionary optimum for transmission among humans. To describe the dynamics of virulence evolution during an H5N1 pandemic, we build a mathematical model based on the patterns of clinical progression in past H5N1 cases. Using both a deterministic model and a stochastic individual-based simulation, we describe (i) the drivers of evolutionary dynamics during an H5N1 pandemic, (ii) the range of case fatalities for which H5N1 viruses can successfully cause outbreaks in humans, and (iii) the effects of different kinds of social distancing on virulence evolution. We discuss two main epidemiological–evolutionary features of this system (i) the delaying or slowing of an epidemic which results in a majority of hosts experiencing an attenuated virulence phenotype and (ii) the strong evolutionary pressure for lower virulence experienced by the virus during a period of intense social distancing.


2010 ◽  
Vol 20 (03) ◽  
pp. 849-857 ◽  
Author(s):  
JULIA PONCELA ◽  
JESÚS GÓMEZ-GARDEÑES ◽  
YAMIR MORENO ◽  
LUIS MARIO FLORÍA

In this paper we study the cooperative behavior of agents playing the Prisoner's Dilemma game in random scale-free networks. We show that the survival of cooperation is enhanced with respect to random homogeneous graphs but, on the other hand, decreases when compared to that found in Barabási–Albert scale-free networks. We show that the latter decrease is related to the structure of cooperation. Additionally, we present a mean field approximation for studying evolutionary dynamics in networks with no degree-degree correlations and with arbitrary degree distribution. The mean field approach is similar to the one used for describing the disease spreading in complex networks, making a further compartmentalization of the strategists partition into degree-classes. We show that this kind of approximation is suitable to describe the behavior of the system for a particular set of initial conditions, such as the placement of cooperators in the higher-degree classes, while it fails to reproduce the level of cooperation observed in the numerical simulations for arbitrary initial configurations.


Author(s):  
Henrik Jeldtoft Jensen

We consider an evolving network of a fixed number of nodes. The allocation of edges is a dynamical stochastic process inspired by biological reproduction dynamics, namely by deleting and duplicating existing nodes and their edges. The properties of the degree distribution in the stationary state is analysed by use of the Fokker–Planck equation. For a broad range of parameters, exponential degree distributions are observed. The mechanism responsible for this behaviour is illuminated by use of a simple mean field equation and reproduced by the Fokker–Planck equation. The latter is treated exactly, except for an approximate treatment of the degree–degree correlations. In the limit of 0 mutations, the degree distribution becomes a power law with exponent 1.


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