title: Accurate noise projection for reduced stochastic epidemic models.
abstract: We consider a stochastic susceptible-exposed-infected-recovered (SEIR) epidemiological model. Through the use of a normal form coordinate transform, we are able to analytically derive the stochastic center manifold along with the associated, reduced set of stochastic evolution equations. The transformation correctly projects both the dynamics and the noise onto the center manifold. Therefore, the solution of this reduced stochastic dynamical system yields excellent agreement, both in amplitude and phase, with the solution of the original stochastic system for a temporal scale that is orders of magnitude longer than the typical relaxation time. This new method allows for improved time series prediction of the number of infectious cases when modeling the spread of disease in a population. Numerical solutions of the fluctuations of the SEIR model are considered in the infinite population limit using a Langevin equation approach, as well as in a finite population simulated as a Markov process.
authors.affiliation: Nonlinear Dynamical Systems Section, Plasma Physics Division, US Naval Research Laboratory, Code 6792, Washington, DC 20375, USA. eric.forgoston.ctr@nrl.navy.mil
authors.forename: Eric
authors.initials: E
authors.lastname: Forgoston
authors.forename: Lora
authors.initials: L
authors.lastname: Billings
authors.forename: Ira B
authors.initials: IB
authors.lastname: Schwartz
mesh_terms: D000818:Animals; D003198:Computer Simulation; D004196:Disease Outbreaks / Q000706:statistics & numerical data*; D006801:Humans; D008954:Models, Biological; D015233:Models, Statistical; D017711:Nonlinear Dynamics; D011157:Population Dynamics; D015995:Prevalence; D018570:Risk Assessment / Q000379:methods; D012307:Risk Factors; D013269:Stochastic Processes