  We develop a mechanistic model that classifies individuals both in terms of
epidemiological status (SIR) and vaccination attitude (willing or unwilling),
with the goal of discovering how disease spread is influenced by changing
opinions about vaccination. Analysis of the model identifies existence and
stability criteria for both disease-free and endemic disease equilibria. The
analytical results, supported by numerical simulations, show that attitude
changes induced by disease prevalence can destabilize endemic disease
equilibria, resulting in limit cycles.
