This essay explores why the COVID-19 vaccine take-up rate is relatively lower in the adult group, despite its benefits and effectiveness. Leveraging a Berry-Levinsohn-Pakes (BLP) demand framework, I estimate how local pandemic severity and demographic factors shape individual’s vaccination behavior across states. The analysis reveals that disadvantaged groups—those with lower education, poorer health, and unemployment—are more likely to postpone their vaccination plans, while younger individuals are more responsive to changes in perceived risk. These findings call for careful policy design that accounts for spatial and age-specific heterogeneity in vaccination hesitancy.