Based on the biopsychosocial (BPS) medical model, this study focuses on HPV vaccination behavior among adolescent females. It aims to explore the influence of multidimensional factors-including biological characteristics, psychological factors, and family and social environments-on vaccination behavior, and to evaluate the effectiveness of a comprehensive HPV vaccination intervention program designed for joint participation by adolescents and their parents.

This study employs a prospective, multicenter, randomized, open-label, parallel-group design. Participants-girls and adolescents aged 9-17 who are scheduled to receive or have not yet completed HPV vaccination, along with their primary caregivers-were recruited from our hospital and collaborating pediatric/maternal and child health institutions both domestically and internationally. Participants were randomly assigned in a 1:1 ratio to an intervention group and a control group.

In addition to routine vaccination clinic counseling, the intervention group received a comprehensive HPV vaccination intervention program based on the BPS model, including: structured health education materials (illustrated booklets/short videos); structured communication and shared decision-making support in the clinic setting; continuous information dissemination and vaccination reminders via platforms such as WeChat; and personalized follow-up and Q&A sessions for families with high vaccine hesitancy; The control group received standard routine education and vaccination services.

The primary outcome was the proportion of adolescents who completed the first dose of the HPV vaccine within 3 months of enrollment; secondary outcomes included the proportion completing the full vaccination series within 6 months, changes in vaccine hesitancy levels and HPV-related knowledge, changes in anxiety/depression levels among adolescents and caregivers, and changes in the quality of parent-child communication regarding health and vaccination as well as family decision-making patterns.

This study is expected to identify key bio-psycho-social determinants of HPV vaccination behavior among adolescent females, validate the effectiveness of the comprehensive BPS intervention in increasing vaccination rates and improving decision-making experiences and psychosocial outcomes, and provide evidence-based guidance and scalable practical pathways for pediatric and related specialty clinics to implement adolescent vaccination health promotion and family shared decision-making services.

Inclusion Criteria:

1. Female, aged 9-17 years (inclusive of 9 and 17 years old).
2. Attending pediatric & adolescent gynecology, adolescent health clinics, or related pediatric/child healthcare clinics at the research centers; or attending vaccination clinics for non-HPV vaccinations (e.g., influenza, tetanus).
3. Has not received any dose of HPV vaccine and has no definitive plan for HPV vaccination on the day of the visit (confirmed by investigator inquiry).
4. Accompanied by at least one primary caregiver (parent or legal guardian) who can comprehend the study content and is willing to participate in shared decision-making interventions.
5. Plans to reside mostly in the region where the research center is located for the next 12 months to facilitate follow-up.
6. Caregiver provides written informed consent; adolescent provides informed consent/assent per local ethical requirements.

Exclusion Criteria:

1. Previous completion of or initiation of any HPV vaccine series.
2. History of severe allergic reaction to any HPV vaccine or its main components, or assessed by a vaccinating physician as currently unsuitable for HPV vaccination.
3. Comorbid severe physical illness (e.g., severe cardiopulmonary disease, active malignancy) or severe mental disorder, judged by the investigator as unsuitable for participation or likely unable to complete follow-up.
4. Participation in other clinical studies highly related to HPV vaccination behavior intervention within the past year, which may interfere with the evaluation of this study's intervention effect.
5. Currently receiving treatment for HPV-related diseases (e.g., genital warts) where the physician considers vaccination currently inadvisable.
6. History of autoimmune diseases or tumors.
7. Other situations deemed by the investigator to affect study adherence or interpretation of results (e.g., families with extremely high mobility).