Sustained impact of motivational interviewing on reducing vaccine hesitancy among postpartum mothers: A randomized control trial, Southeastern France, 2021 to 2022

Parental vaccine hesitancy (VH) remains a significant public health challenge in France, despite mandatory childhood vaccination policies. Motivational interviewing (MI) has shown promise in reducing VH and increasing vaccination intentions. This study aimed to evaluate the sustained impact of an MI-based intervention on VH and vaccination intentions among postpartum mothers in Southeastern France. We conducted a randomized controlled trial (RCT) in two maternity wards in Southeastern France between November 2021 and April 2022. A total of 733 mothers were randomly assigned to receive either a MI session delivered by trained midwives or an educational leaflet. We used the Parent Attitudes about Childhood Vaccines questionnaire to assess VH (0-100 score) and a single question to measure vaccination intentions (1-10 score). Data on VH and vaccination intentions were collected pre-intervention (T0), immediately post-intervention (T1), and seven months later on average (T2). Linear regression models adjusted on potential confounders and Heckman's two-step selection method were used to analyze the data. Seven months post-intervention, we observed a reduction in VH scores (10.1/100 points, <i>p</i> < .0001) and an increase in vaccination intention scores (0.8/10 points, <i>p</i> = .01) compared to the control group. The impact of MI was consistent across different perceived financial situations. Our findings demonstrate that MI has a sustained effect in reducing VH and increasing vaccination intentions among postpartum mothers. MI should be considered as a key strategy to strengthen and sustain vaccine confidence. Further research is needed to test the impact of MI interventions among other under-vaccinated populations, such as pregnant women.