Behavioural economics to improve and motivate vaccination in primary care using nudges through the electronic health record: rationale and design of the BE IMMUNE randomised clinical trial

Introduction Annual influenza vaccination reduces disease burden but vaccination rates are suboptimal, with persistent disparities among subpopulations. The purpose of this trial is to evaluate multicomponent behavioural economic nudge interventions to clinicians and patients to increase influenza vaccination. This trial also includes an intensification nudge to reduce disparities in vaccination among older adult, primary care patients.Methods This is a two-part, multisite cluster randomised, pragmatic clinical trial. In the first part, a multicomponent nudge intervention will be tested over approximately 6 months (September 2023-February 2024). The second part consists of a replication trial conducted at an additional site during the following influenza season (September 2024-February 2025). Primary care clinics will be randomised to the nudge intervention or usual care. Eligible clinicians and patients at intervention clinics will receive the intervention, and patients deemed high risk for not receiving a vaccine will be further randomised to receive an intensification nudge. The primary outcome is vaccine completion during the eligible visit and the secondary outcome is vaccine completion within 3 months of the eligible visit.Analysis The effect of the clinic-level nudge intervention on the primary and secondary outcomes will be evaluated using generalised estimating equations (GEEs) with a clinic-level exchangeable working correlation to account for clustering of observations within the clinic. GEE models with an independent working correlation will be used to evaluate the impact of the additional intensification nudge on the primary and secondary outcomes.Ethics and dissemination The University of Pennsylvania Institutional Review Board (IRB) approved this trial and serves as the single IRB of record (IRB #851838). Results will be disseminated via peer-reviewed publication and conference presentations.Trial registration number NCT06057727.