AI Chatbot Use for Human Papillomavirus Vaccine Literacy in Japan

Importance Persistent misinformation and low confidence impede human papillomavirus (HPV) vaccine uptake in Japan. Artificial intelligence (AI)–driven conversational agents may provide scalable vaccine education, but randomized evidence for HPV vaccine communication remains limited. Objective To determine whether an AI-driven HPV vaccine chatbot improves caregiver HPV vaccine literacy compared with a government leaflet. Design, Setting, and Participants Parallel-group randomized clinical trial (RCT) conducted through a national research panel of female caregivers in Japan with unvaccinated daughters aged 12 to 18 years from November 30 to December 27, 2024, with 2-week follow-up. Interventions Participants were randomized 1:1 to an AI-driven HPV vaccine chatbot or standard government HPV vaccine leaflet. Main outcomes and measures The primary outcome was an HPV vaccine literacy, evaluated immediately after intervention to estimate immediate intervention efficacy and evaluated at 2-week follow-up to estimate durability. HPV vaccine literacy was measured using 7 factual questions about HPV and HPV vaccination; scores are shown on a 0 to 7 scale, with higher scores indicating more correct responses.The secondary outcome was decision to vaccinate at 2-week follow-up. Results Among 848 randomized participants, 704 of 841 (83.7%) were included in the immediate modified intention-to-treat (mITT) analysis (353 chatbot, 351 leaflet) and 477 of 841 (56.7%) in the mITT analysis at 2 weeks (237 chatbot, 240 leaflet). A total of 447 of 703 participants (63.6%) were aged 40 to 49 years and had college or university education (472 of 703 participants [67.1%]). Immediately after the intervention, analysis of covariance-adjusted literacy was higher with the chatbot (adjusted mean difference, 0.30 points on the 0 to 7 scale; 95% CI, 0.18-0.43 points; P < .001). At the 2-week durability assessment, mean (SD) literacy increased by 0.40 (1.21) with the chatbot vs 0.28 (1.13) points with the leaflet; adjusted literacy again favored the chatbot (adjusted mean difference, 0.30 points; 95% CI, 0.13-0.47; P < .001). At 2 weeks, caregivers’ vaccination decisions did not differ between groups (102 of 253 participants [40.3%] vs 103 of 260 participants [39.6%]; adjusted odds ratio, 0.74; 95% CI, 0.41 to 1.33; P = .31). Conclusions and Relevance In this RCT of female caregivers in Japan, an AI-driven HPV vaccine chatbot produced higher adjusted HPV vaccine literacy than a government leaflet immediately after intervention and at 2-week follow-up, without a measurable short-term effect on vaccination decision. Conversational AI may complement official materials and health care professional recommendations. Trial Registration ClinicalTrials.gov Identifier: NCT06702423