  A nudge changes people's actions without removing their options or altering
their incentives. During the COVID-19 vaccine rollout, the Swedish Region of
Uppsala sent letters with pre-booked appointments to inhabitants aged 16-17
instead of opening up manual appointment booking. Using regional and municipal
vaccination data, we document a higher vaccine uptake among 16- to 17-year-olds
in Uppsala compared to untreated control regions (constructed using the
synthetic control method as well as neighboring municipalities). The results
highlight pre-booked appointments as a strategy for increasing vaccination
rates in populations with low perceived risk.
