Aim This study investigated the effect of a multifaceted intervention on fu vaccination rates among French healthcare workers (HCWs) and the characteristics of HCWs who were hesitant to vaccinate. Subject and methods HCWs (N = 983, Mage = 40.65, SD = 11.42) participated in a four-arm randomized controlled trial. The first group watched an informative video on vaccination (n = 286), the second group completed a survey on anticipated regret and the planning technique (n = 221), and the third group underwent the complete intervention (i.e., the video, anticipated regret, and planning technique; n = 253); the fourth group was the control group (n = 223). Three months later, they were sent a survey to measure their vaccination intention and behavior. The primary outcome was the vaccination rate, while the secondary outcome was the vaccination intention score. Results Altogether, 137 HCWs were analyzed. No significant effect of the intervention on the vaccination rate (p = .67, pseudo-R2 = .008) or vaccination intention (p = .85, n2p = .003, 95% CI [.000, .01]) among HCWs was observed. Additionally, factors such as attitude, self-efficacy, outcome expectations, and risk perception signifcantly infuenced T1 and T2 vaccination. HCWs with a higher socioeconomic status (SES) were more likely to be vaccinated than those with a lower or middle SES. No adverse events were reported. Conclusion Vaccination behavior raises questions about the efficacy of the planning technique, which appears to be more effective for HCWs with a high SES. Tailored, multi-intervention approaches seem necessary.