COVID-19 remains a public health threat, with U.S. vaccination rates too low for herd immunity. This study examines how health messaging elements—vested interests, reactance, and perceived threat—influence vaccine hesitancy. Survey data from 1,588 U.S. adults show that reactance, especially among conservatives, strongly predicts lower vaccine acceptance. Liberals showed similar but weaker effects. To increase vaccine uptake, messaging should avoid triggering resistance by respecting individual freedom and emphasizing personal choice. Recommendations for such messaging approaches are provided. Read it here...