From regional pulse vaccination to global disease eradication: insights from a mathematical model of Poliomyelitis

TL;DR

This paper presents a mathematical model analyzing pulse vaccination strategies for poliomyelitis, emphasizing the importance of synchronizing campaigns across regions and timing with seasonal pathogen circulation to enhance eradication efforts.

Contribution

It introduces a comprehensive model incorporating seasonality, environmental reservoirs, and regional vaccination schedules, providing new insights into optimal pulse vaccination deployment.

Findings

Synchronizing pulse vaccinations across regions is crucial.

Timing vaccinations with seasonal pathogen peaks improves effectiveness.

Migration imbalances influence the optimal distribution of vaccines.

Abstract

Mass-vaccination campaigns are an important strategy in the global fight against poliomyelitis and measles. The large-scale logistics required for these mass immunisation campaigns magnifies the need for research into the effectiveness and optimal deployment of pulse vaccination. In order to better understand this control strategy, we propose a mathematical model accounting for the disease dynamics in connected regions, incorporating seasonality, environmental reservoirs and independent periodic pulse vaccination schedules in each region. The effective reproduction number, $R_e$, is defined and proved to be a global threshold for persistence of the disease. Analytical and numerical calculations show the importance of synchronising the pulse vaccinations in connected regions and the timing of the pulses with respect to the pathogen circulation seasonality. Our results indicate that it may be crucial for mass-vaccination programs, such as national immunisation days, to be synchronised across different regions. In addition, simulations show that a migration imbalance can increase $R_e$ and alter how pulse vaccination should be optimally distributed among the patches, similar to results found with constant-rate vaccination. Furthermore, contrary to the case of constant-rate vaccination, the fraction of environmental transmission affects the value of $R_e$ when pulse vaccination is present.