The gap in knowledge and information-seeking between high and low socioeconomic status (SES) has been well documented. This study extends this knowledge gap hypothesis to narrative persuasion in the context of parents' knowledge and information-seeking intention concerning adolescents' COVID-19 vaccination. It specifically tests if the gap is moderated by a message type (narrative vs. non-narrative). An online quasi-experiment, with a 2 (participants' education level: high vs. low) × 3 (message type: narrative vs. non-narrative vs. no-message) between-subject design, showed a main effect of education level (i.e., parents with a higher [vs. lower] education level rated a higher intention to seek information and provided more correct answers on questions about adolescents' COVID-19 vaccination) and an interaction between the two factors. The interaction showed that the gap between high- and low-education groups in information-seeking intention disappeared among those who read the narrative or non-narrative, and the gap in knowledge disappeared among those who read the narrative. Study findings suggest the utility of narratives in narrowing the gap in knowledge and information-seeking to improve parents' decisions on child vaccination.