Population-level herd immunity from equine influenza vaccination protects individual horses including those that cannot be vaccinated, creating welfare benefits beyond the vaccinated individual.
Equine influenza vaccination is a population-level welfare intervention whose effects extend beyond individually vaccinated horses to protect those that cannot be vaccinated — very young foals, horses with immune disorders, and horses in which vaccination is temporarily contraindicated. When competition communities maintain high vaccination compliance, the welfare benefit of herd immunity protects all members including the most vulnerable. Outbreaks in under-vaccinated populations cause serious welfare harm across many animals simultaneously. The welfare case for equine influenza vaccination is therefore both individual and collective — protecting your horse protects the whole community. Competition requirements for current vaccination are one of the most effective mechanisms for maintaining the compliance needed for genuine herd protection.