# A modelling assessment of the impact of control measures on highly pathogenic avian influenza transmission in poultry in Great Britain

## TL;DR

This study models how control measures can reduce the spread of bird flu in British poultry and lower health risks.

## Contribution

A spatial transmission model calibrated to real outbreak data to assess the impact of control measures on avian influenza spread.

## Key findings

- Reducing susceptibility around infected premises significantly lowers the number of infected poultry premises.
- Localized interventions like enhanced biosecurity or vaccination can curb transmission effectively.
- Effective control strategies are crucial to limit avian influenza circulation and public health threats.

## Abstract

Since 2020, large-scale outbreaks of highly pathogenic avian influenza (HPAI) H5N1 in Great Britain have resulted in substantial poultry mortality and economic losses. Alongside the costs, the risk of circulation leading to a viral reassortment that causes zoonotic spillover raises additional concerns. However, the precise mechanisms driving transmission between poultry premises and the impact of potential control measures in Great Britain, such as vaccination, are not fully understood. We have developed a spatial transmission model for the spread of HPAI in poultry premises calibrated to infected premises data for the 2022–23 season using Markov chain Monte Carlo. Our results indicate that reducing the susceptibility of the premises surrounding an identified infected premises (for example, through enhanced biosecurity measures and/or vaccination) can substantially reduce the overall number of infected premises. Our findings highlight that enhanced control measures could limit the future impact of HPAI on the poultry industry and reduce the risk of broader health threats.

Highly pathogenic avian influenza is an infectious disease that has caused a substantial number of outbreaks in bird populations around the world. This includes poultry populations in Great Britain, where the largest number of infected poultry premises were reported in the 2022–23 season. This identifies the need for mathematical models to be calibrated to outbreak data, such that we can have a greater understanding of the disease transmission process and the potential measures that could be used to avert future infections. We have developed a model to describe temporal changes in avian influenza infections in poultry premises in Great Britain over the course of an epidemic season. We then simulate reactive enhanced control strategies that reduce susceptibility of poultry to show that there is a large benefit in localised interventions around an infected poultry premises to reduce further transmission. These results underscore the need for effective control strategies to limit the continued circulation of avian influenza and the threat to public health.