Incentivizing Vaccination through Reserved Dose Messages

Sending text messages informing individuals that a vaccine dose is reserved for them while at a doctor's appointment significantly increased vaccination rates. This piggyback messaging approach, where individuals were encouraged to consider getting vaccinated while already at the doctor's office, proved to be one of the most effective nudges, outperforming other strategies. The personalized nature of the message, implying a default action of vaccination, and offering a single-step path to obtaining the vaccine contributed to its success.