Background: Human papillomavirus (HPV) are a major cause of preventable cancers, yet France has one of the lowest HPV vaccination coverage rates in Western Europe, remaining far below WHO elimination targets. To address this gap, a national school?based HPV vaccination program targeting all 7th?grade students was introduced in 2023, requiring written consent signed by both parents (digital or paper). Early monitoring indicates improved uptake, but substantial disparities persist across schools and regions. While school?based programs have proven effective internationally, little is known about the operational and behavioral factors shaping implementation outcomes in the French context.

Objectives: This study examines the determinants influencing parental consent forms submission to inform strategies for strengthening school?based HPV vaccination in a French district comprising 358 schools.

Methods: A convergent parallel mixed-methods design was used to examine operational, institutional, and behavioral determinants of parental consent form return. A purposive sample of 30 secondary schools was selected to capture diversity in institutional characteristics and implementation contexts; 17 schools agreed to participate and completed a self-administered online questionnaire. Quantitative data were analyzed using descriptive statistics. Schools were categorized by consent form return rates: ≥25% were classified as high-performing and <25% as low-performing. Concurrently, a nested subsample of 12 staff members responsible for campaign coordination and who had completed the questionnaire participated in phone-based semi-structured interviews. Interviews were documented verbatim and analyzed following Consolidated Criteria for Reporting Qualitative Research guidelines. Findings from both strands were integrated during analysis. Interpretation was guided by the NASSS framework, the Health Belief Model, and Diffusion of Innovation theory.

Results: Consent form return rates varied widely and were shaped by institutional capacity, coordination, and communication practices. Smaller, often rural schools achieved higher returns, supported by broader staff involvement (+25.7-point difference in follow-up completion). School nurses played a central role: 70.6% of high-performing schools designated the nurse as campaign lead, and nurses were involved in 100% of these schools. In contrast, 28.6% of low-performing schools had no full-time nurse, compared with universal full- or part-time nurse presence in high-performing schools. Schools relying exclusively on digital consent reported lower effectiveness, with 60% indicating digital formats were unsuitable for some families. Some high-performing schools introduced HPV vaccination information during the mandatory 6th-grade nurse health assessment, perceived by staff as a key facilitator. Barriers included limited parental health literacy, cultural or moral concerns, and perceptions of 7th-grade age appropriateness. Early parental engagement and coordinated school-level efforts consistently emerged as facilitators.

Conclusion: This study highlights facilitators and barriers across the full implementation chain of the school-based HPV vaccination campaign. Operational constraints underscore the pivotal role of school nurses, while limited health literacy reduces parental engagement. The findings demonstrate the added value of involving parents earlier, beginning in 6th grade, to build awareness, trust, and effective communication ahead of vaccination. Although conducted in a single district, results align with broader regional trends: the region recorded a 29-point increase in HPV vaccination coverage compared with pre-campaign levels, positioning it as a leading performer in the 2024–2025 national rollout.