Assessing the effects of limited vaccine supply on risk-based vaccination strategies in regions of endemic foot-and-mouth disease

Foot-and-mouth disease is an important livestock disease which is endemic in many regions of the world, many of which struggle to supply enough vaccine doses to cover the entire population of animals at risk. We use a previously fitted stochastic metapopulation model of FMD spread to simulate four plausible vaccine allocation strategies in the context of limited vaccine supply and endemic disease. We find that random allocation outperforms other strategies when the objective is to minimise average prevalence, and random allocation also achieves local eradication at lower doses per capita. However, all strategies perform similarly when minimising annual incidence, with the ‘optimal’ allocation strategy varying by doses available per capita. These results suggest that policymakers in regions of endemic FMD should focus more on sourcing high-quality vaccines and achieving high coverage, with risk-based vaccination being a secondary concern.