Abstract

Background/Objectives: Human papillomavirus (HPV) vaccination coverage among adolescents remains below public health targets despite strong evidence of vaccine effectiveness in preventing HPV-related cancers. Digital interventions (e.g., serious games) may improve HPV vaccine uptake, but evidence for effects on vaccination behavior remains limited. Methods: This secondary analysis of a randomized controlled trial evaluated a co-designed, game-based digital intervention to increase HPV vaccine initiation among unvaccinated youth aged 11–14 years and their parents. The sample included 64 parent–adolescent dyads (33 intervention and 31 usual care dyads). The primary outcome was HPV vaccine initiation at 2-month follow-up. Results: A significantly greater proportion of adolescents in the intervention group initiated HPV vaccination compared with controls (88.5% vs. 46.2%; χ2(1) = 10.58, p = 0.001; risk difference = 0.423, 95% CI = [0.196, 0.650]). No significant between-group baseline differences were observed in parent HPV vaccination intention, knowledge, or psychosocial perceptions, although adolescent vaccination intention was higher in the intervention group. In adjusted logistic regression controlling for adolescent baseline HPV vaccination intention, intervention participants remained significantly more likely to initiate vaccination than controls (OR = 9.31, 95% CI = 2.13–40.70, p = 0.003). Intervention acceptability was high, with most parents and adolescents reporting that the game was easy to use, engaging, and relevant to vaccination decision-making. Conclusions: These findings provide preliminary evidence that a brief, family-centered, game-based digital intervention may help increase HPV vaccination initiation among adolescents. Larger trials with longer follow-up are needed to assess vaccine series completion and effectiveness across diverse settings.

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