Effectiveness of CONFIVAC, an intervention to enhance Paediatric Nurses and Paediatricians skills to promote vaccination: a mixed-methods cluster randomised clinical trial

Background Vaccine hesitancy (VH) poses a significant challenge to achieving optimal vaccination coverages worldwide. Paediatric healthcare workers (PHCWs) are fundamental in promoting vaccination but often lack adequate training to address VH. We designed CONFIVAC, an evidence-based training program developed using intervention mapping to enhance PHCWs' knowledge, self-efficacy, and skills in managing VH and fostering a culture of immunization in primary care. This study aimed to evaluate its effectiveness. Methods We conducted a mixed methods study including a cluster-randomized controlled trial with142 PHCWs in Barcelona and Central Catalonia, Spain from October 2023 to February 2024 and a qualitative study using a thematic analysis. Paediatric teams were randomized into intervention (CONFIVAC) and control (standard care) arms. CONFIVAC included 12 hours of online and in-person training on vaccine knowledge, communication strategies, and organizational tools. Outcomes were assessed through self-administered questionnaires at baseline (T0) and four months later (T1). Key outcomes included vaccine-promoting behaviours (presumptive communication, anticipation of upcoming vaccines, and explicit vaccine recommendations) and self-perception of adequate training to handle VH. We performed logistic regression models to estimate odds ratios (OR) with 95% confidence intervals using an intention-to-treat approach. Focus groups provided qualitative insights. Results At T1, PHCWs in the intervention arm were more likely to use presumptive communication (aOR: 4.05 [2.30;7.15]) and anticipate upcoming vaccines (aOR: 2.64 [1.50;4.65]) than controls. Explicitly recommending vaccination when encountering cases of VH did not reach statistical significance (aOR: 1.75 [0.89;3.44]). Self-perception of adequate training was higher in the intervention arm (aOR: 3.85 [2.10;7.03]). Satisfaction with the training was high, and focus group participants reported improved communication strategies, more empathy towards VH families, and increased confidence in managing VH situations. Discussion CONFIVAC enhanced PHCWs' vaccine-promoting behaviours and self-efficacy, demonstrating the value of accessible, evidence-based training programs to support vaccination efforts in routine practice. Trial registration ClinicalTrials NCT06489236