How high vaccination rates in dog populations create community immunity that protects vulnerable puppies and unvaccinated dogs.
Parvovirus prevention through vaccination is an example of where individual welfare decisions contribute to collective protection. When most dogs in a community are vaccinated, the pathogen has fewer hosts to circulate in, reducing the risk for vulnerable individuals including very young puppies before their vaccine series is complete. Low vaccination areas function as reservoirs that sustain pathogen circulation affecting both their own dogs and those of adjacent communities. Community-level vaccination programmes — particularly in areas with low income access to veterinary care — provide population-level welfare benefits that individual vaccination decisions alone cannot achieve. This is a compelling welfare argument for subsidised vaccination programmes in underserved communities.