## The Annals of Applied Probability

### An epidemic in a dynamic population with importation of infectives

#### Abstract

Consider a large uniformly mixing dynamic population, which has constant birth rate and exponentially distributed lifetimes, with mean population size $n$. A Markovian SIR (susceptible $\to$ infective $\to$ recovered) infectious disease, having importation of infectives, taking place in this population is analysed. The main situation treated is where $n\to\infty$, keeping the basic reproduction number $R_{0}$ as well as the importation rate of infectives fixed, but assuming that the quotient of the average infectious period and the average lifetime tends to 0 faster than $1/\log n$. It is shown that, as $n\to\infty$, the behaviour of the 3-dimensional process describing the evolution of the fraction of the population that are susceptible, infective and recovered, is encapsulated in a 1-dimensional regenerative process $S=\{S(t);t\ge0\}$ describing the limiting fraction of the population that are susceptible. The process $S$ grows deterministically, except at one random time point per regenerative cycle, where it jumps down by a size that is completely determined by the waiting time since the start of the regenerative cycle. Properties of the process $S$, including the jump size and stationary distributions, are determined.

#### Article information

Source
Ann. Appl. Probab., Volume 27, Number 1 (2017), 242-274.

Dates
Revised: February 2016
First available in Project Euclid: 6 March 2017

https://projecteuclid.org/euclid.aoap/1488790828

Digital Object Identifier
doi:10.1214/16-AAP1203

Mathematical Reviews number (MathSciNet)
MR3619788

Zentralblatt MATH identifier
1380.92062

#### Citation

Ball, Frank; Britton, Tom; Trapman, Pieter. An epidemic in a dynamic population with importation of infectives. Ann. Appl. Probab. 27 (2017), no. 1, 242--274. doi:10.1214/16-AAP1203. https://projecteuclid.org/euclid.aoap/1488790828

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