Adherence to palivizumab prophylaxis programmes is crucial to protect infants with CHD against respiratory syncytial virus infections. We analysed the effectiveness of two nudge interventions in increasing adherence.

Our study included 229 infants, and their caregivers, from five centers in Turkey in the 2020–2021 respiratory syncytial virus season. We randomly allocated caregivers to a control and two intervention groups. Caregivers in all groups were informed about the prophylaxis programme and provided a schedule. Additionally, caregivers in Intervention 1 were called two days before appointments (default bias) and were asked to plan the appointment day (implementation intention), whereas caregivers in Intervention 2 received biweekly text messages informing them about the programme’s benefits (availability bias) and current adherence rate (social norm).

Caregivers in Intervention 1 had a significantly higher adherence rate than Control (97.3% versus 90.9%) (p = 0.014). Both interventions had a significant effect on participants in their first prophylaxis season (p = 0.031, p = 0.037). Families where the father was employed had a 14.2% higher adherence rate (p = 0.001). Every additional child was associated with a 2.2% decrease in adherence rate (p = 0.02). In control, ICU admission history was associated with an 18.8% lower adherence rate (p = 0.0001), but this association disappeared in intervention groups.

This is the first prospective interventional study which, in the context of palivizumab prophylaxis, analyses the effectiveness of nudge interventions based on established cognitive biases by comparing randomly generated intervention and control groups. We found that default bias and implementation intention have significant effects on adherence.

Clinical trial, in the name and number “Adherence of palivizumab prophylaxis, NCT05778240” registered retrospectively. https://clinicaltrials.gov/ct2/show/NCT05778240.