Logistical constraints lead to an intermediate optimum in outbreak response vaccination
Authored by Katriona Shea, Yun Tao, Matthew Ferrari
Date Published: 2018
DOI: 10.1371/journal.pcbi.1006161
Sponsors:
United States National Institutes of Health (NIH)
United States National Science Foundation (NSF)
Platforms:
No platforms listed
Model Documentation:
ODD
Mathematical description
Model Code URLs:
Model code not found
Abstract
Dynamic models in disease ecology have historically evaluated
vaccination strategies under the assumption that they are implemented
homogeneously in space and time. However, this approach fails to
formally account for operational and logistical constraints inherent in
the distribution of vaccination to the population at risk. Thus,
feedback between the dynamic processes of vaccine distribution and
transmission might be overlooked. Here, we present a spatially explicit,
stochastic Susceptible-Infected-Recovered-Vaccinated model that
highlights the density-dependence and spatial constraints of various
diffusive strategies of vaccination during an outbreak. The model
integrates an agent-based process of disease spread with a partial
differential process of vaccination deployment. We characterize the
vaccination response in terms of a diffusion rate that describes the
distribution of vaccination to the population at risk from a central
location. This generates an explicit trade-off between slow diffusion,
which concentrates effort near the central location, and fast diffusion,
which spreads a fixed vaccination effort thinly over a large area. We
use stochastic simulation to identify the optimum vaccination diffusion
rate as a function of population density, interaction scale,
transmissibility, and vaccine intensity. Our results show that,
conditional on a timely response, the optimal strategy for minimizing
outbreak size is to distribute vaccination resource at an intermediate
rate: fast enough to outpace the epidemic, but slow enough to achieve
local herd immunity. If the response is delayed, however, the optimal
strategy for minimizing outbreak size changes to a rapidly diffusive
distribution of vaccination effort. The latter may also result in
significantly larger outbreaks, thus suggesting a benefit of allocating
resources to timely outbreak detection and response
Tags
Agent-based models
Dynamics
intervention
Strategies
Mouth-disease
Measles epidemics
Foot
House-to-house
Mass vaccination
Smallpox attack