Behavioural nudges increase COVID-19 vaccinations

Enhancing vaccine uptake is a critical public health challenge. Overcoming vaccine hesitancy and failure to follow through on vaccination intentions requires effective communication strategies. Here we present two sequential randomized controlled trials to test the effect of behavioural interventions on the uptake of COVID-19 vaccines. We designed text-based reminders that made vaccination salient and easy, and delivered them to participants drawn from a healthcare system one day (first randomized controlled trial) (n = 93,334 participants; clinicaltrials number NCT04800965) and eight days (second randomized controlled trial) (n = 67,092 individuals; clinicaltrials number NCT04801524) after they received a notification of vaccine eligibility. The first reminder boosted appointment and vaccination rates within the healthcare system by 6.07 (84%) and 3.57 (26%) percentage points, respectively; the second reminder increased those outcomes by 1.65 and 1.06 percentage points, respectively. The first reminder had a greater effect when it was designed to make participants feel ownership of the vaccine dose. However, we found no evidence that combining the first reminder with a video-based informative intervention (designed to address vaccine hesitancy) increased uptake. We also conducted online studies (n = 3,181 participants) to examine vaccination intentions, which revealed patterns that diverged from those of the first trial; this underscores the importance of pilot-testing interventions in the field. Our findings inform the design of behavioural nudges for promoting health decisions, and highlight the value of making vaccination easy and inducing feelings of ownership over vaccines.