Evaluation of theory-based interventions using behaviour change techniques in randomised controlled trials on vaccination behaviour: a meta-analysis.

OBJECTIVE: This meta-analysis examined behaviour change techniques (BCTs) used in theory-based randomised controlled trials (RCTs) targeting vaccination uptake. Electronic databases identified 44 studies (N = 428,931). DESIGN: This review was conducted from September to December 2020 and updated in April 2024. It included RCTs with quantitative vaccination behaviour data. RCT quality was assessed using the Cochrane criteria, Theme Coding Scheme and Quality of Survey Studies in Psychology checklist. BCTs were coded using the taxonomy version 1. MAIN OUTCOME MEASURES: The review included RCTs with quantitative vaccination behaviour data. RESULTS: Interventions had a statistically significant effect on vaccination uptake (OR = 1.56, 95% CI [1.33, 1.81]), with substantial heterogeneity. There was no evidence that BCTs classified as improbable were associated with lower intervention efficacy (ps ≥ .48). Several individual BCTs were associated with larger effects relative to control groups, including BCT 1.2 Problem solving (OR = 1.76, 95% CI [1.30, 2.40]) and BCT 5.3 Information about social and environmental consequences (OR = 1.88, 95%CI [1.37, 2.58]). Some BCT combinations showed descriptively larger effect sizes. For example, BCT 5.3 Information about social and environmental consequences and 13.2 Framing/reframing were associated with larger effects relative to control groups (OR = 3.05, 95%CI [1.58, 5.90]). Moderators had no statistically significant effects (ps ≥ .57). CONCLUSION: Findings identify promising BCTs and highlight the potential value of combining techniques. PRE-REGISTRATION: This study was registered with the Centre for Open Science (OSF): https://osf.io/eyrq8/.