RESUMEN
Objective: Lebanon has historically maintained high immunization coverage rates for most routine vaccines. However, an increase in poverty rates coupled with an influx of over a million refugees posed significant challenges to the national immunization program. In response, an accelerated immunization activities (AIA) program, encompassing community-based outreach and referral activities, was launched to increase the demand for childhood vaccination through the public healthcare system. Despite this effort, uptake among refugee and host community households remained low, resulting in pockets of low immunization coverage rates. This study investigates the barriers that prevent households in low coverage areas from vaccinating their children, and evaluates a behavior change intervention designed to overcome the identified social, perceptual, and cognitive barriers. Methods: Households with un- or under-vaccinated children were recruited from seven cadastres with low immunization coverage rates. A mixed methods approach, including stakeholder interviews and field observations, was employed to identify the main barriers to vaccination. Thereafter, a cluster randomized trial was conducted to evaluate the impact of a visual planning aid comprising five behavior change techniques (nudges) on vaccine uptake. Results: A total of 12,332 un- or under-vaccinated children from 6160 households (3045 (49.4%) control households; 3115 (50.6%) treated households) were reached during the trial. The observed vaccination rates were 13.5% and 20.2% for control and treated households, respectively. This represents a 6.7 percentage points increase in the likelihood of a treated household to vaccinate at least one child, compared to the control group. At least 390 additional children benefited from life-saving vaccines due to the behavioral intervention. Conclusions: This study highlights the importance of integrating behavioral insights into vaccination campaigns and programs, especially in low resource settings, to ensure that more children can benefit from life-saving vaccines.