The HFS intervention was developed in accordance with INACSL Healthcare Simulation Standards and validated by six nursing experts. All participants first received a standardized 100-minute childhood vaccination training consisting of theoretical instruction and laboratory practice. The simulation session included a 10-minute briefing, a 20-minute high-fidelity scenario involving a vaccine-hesitant mother, and a 30-minute structured debriefing using the PEARLS framework. During the simulation, students were required to assess parental concerns, provide education, safely administer vaccines, and complete documentation. The debriefing process included reflection and analysis through structured phases to enhance learning outcomes.

The SLP group received the identical 100-minute theoretical and practical training session. One week later, instead of a structured simulation, they participated in a 20-minute individual skills session in the nursing fundamentals laboratory. Each student independently performed the vaccination procedure on a baby manikin and verbally described the parent education they would provide. Following their session, each student also participated in an individual, video-assisted PEARLS debriefing focused on their technical performance and communication description.

High-fidelity simulation-based training including a vaccine hesitancy scenario, structured briefing, simulation, and debriefing.

A 10-item multiple-choice test developed by the researchers based on national guidelines and literature. Each correct answer is scored as 10 points. Total scores range from 0 to 100, with higher scores indicating greater knowledge of childhood immunization. Expert validation was obtained, and the KR-20 reliability coefficient was 0.93.

Items are scored from 0 (not performed) to 2 (performed). Total scores range from 0 to 40, with higher scores indicating better pediatric intramuscular vaccination administration skills. The checklist demonstrated expert validity and a Cronbach's alpha of 0.90.

A validated 12-item, 5-point Likert scale with two subscales (Satisfaction and Self-Confidence). Total scores range from 12 to 60, with higher scores indicating greater satisfaction and self-confidence in learning. In this study, Cronbach's alpha was 0.96 for the satisfaction subscale, 0.94 for the self-confidence subscale, and 0.96 for the total scale.