Comparative effectiveness of construal-level messaging in the COVID-19 Vaccine Injury Compensation Program in the Republic of Korea: a randomized controlled trial

This study aimed to assess the impact of high-level versus low-level construal messages about the coronavirus disease 2019 (COVID-19) Vaccine Injury Compensation Program (CVICP) on public attitudes toward the program and COVID-19 vaccination. A randomized controlled experimental design was employed. Adults aged 18 to 64 residing in the Republic of Korea were randomly assigned to either an experimental group (high-level construal message) or a control group (low-level construal message). Both groups viewed a 2-minute video about the CVICP, with construal level as the sole variable. Pre- and post-intervention questionnaires evaluated attitudes toward the CVICP and COVID-19 vaccination, including satisfaction, perceived necessity, and perceived effectiveness in enhancing vaccine acceptance. Data were analyzed using the paired t-test, repeated measures 2-way analysis of variance, and multiple linear regression. The experimental group showed statistically significant improvements across all 6 attitude measures following exposure to the high-level construal message. By contrast, the control group demonstrated significant improvement in only 3 attitudes: satisfaction with the CVICP, willingness to recommend vaccination, and willingness for future vaccination. A significant difference between groups was observed for perceived effectiveness of the CVICP in enhancing vaccine acceptance (p=0.01), with high-level construal messaging being more impactful. High-level construal messages are more effective than low-level messages in shaping public perceptions and addressing vaccine hesitancy. Policymakers and health authorities should incorporate high-level construal elements into communication strategies to build trust and support for vaccination programs.