Effect of a multicomponent HPV intervention on self-reported HPV vaccine uptake and intention among French adolescents and parents: results from the national, cluster-randomised PrevHPV trial

Abstract

Background: Human papillomavirus (HPV) infections cause several cancers, including nearly all cervical cancer cases. While there are safe and effective vaccines, the adolescent HPV vaccine coverage in France is low (<50%). Thus, we studied the effect of municipality-wide interventions to increase HPV vaccine uptake and intention among middle school students.

Methods: This cluster-randomised trial used an incomplete factorial design to arrange three components (in-school education, motivation, mobilisation (EMM); in-school vaccination; and local general practitioner (GP) trainings) into six intervention conditions, which were randomly assigned to 91 participating French municipalities. We assessed HPV vaccine status using online self-reported questionnaires that students (typically aged 13-14) and parents completed at baseline and 5-month follow-up. Using adjusted linear regression, we estimated differences in (1) vaccine uptake and (2) uptake and intention to vaccinate, both by randomisation arm and by intervention component. We explored subgroup effects by at-home multilingualism, gender, age and parental education.

Results: 2047 of 2664 (74%) students were unvaccinated against HPV at baseline. The 5-month probability of first-dose vaccine uptake in the control group was 0·09 (95% CI 0.06 to 0.11). Vaccine campaigns alone contributed a 24-percentage-point (0.18, 0.30) increase in uptake compared with the control group. EMM was only effective in increasing vaccine uptake among monolingual francophone students, and we detected no effect from GP training. Vaccine campaigns and EMM both increased the combined outcome of vaccine intention and first-dose uptake, but EMM had the same subgroup effect. Questionnaire data from parents (N=236) were sparser but demonstrated similar overall trends.

Conclusions: Our results demonstrate that in-school HPV vaccine campaigns effectively increase HPV vaccine uptake among adolescents without exacerbating extant disparities in vaccine uptake. EMM can also be a useful tool to increase HPV vaccine intention but must be improved to bridge disparities in its effectiveness. GP training results were inconclusive.

Trial registration number: NCT04945655.

Keywords: Education; Human Papillomavirus Viruses; Public Health; School Health Services; Vaccination.

Figure 1. Participant flowchart. ¹Estimates of 30% class non-participation were extrapolated based on the EMM sample of classrooms. ²Identification numbers (IDs) in questionnaires allowed unique identification of schools but not classrooms, therefore, class participation in questionnaires cannot be directly calculated. ³Not included in calculation of loss to follow-up. EMM, education, motivation,

Figure 2. Risk differences (relative to control arm) in first-dose uptake per intervention component, stratified by adolescents’ gender (A), grade (B), multilingualism (C), and parental education (D). ¹Reference level for risk difference is the control arm (no intervention) within each stratum; no baseline vaccine propensity adjustment. In (C) the CI for multilingual students in municipalities receiving GP training was 0.04 (95% CI: −0.003 to 0.09). The point estimate for monolingual students in municipalities receiving GP training was −0.04 (−0.07 to −0.001). EMM, education, motivation, mobilisation; FA, facilitation of access; GP, general practitioner; HPV, human papillomavirus.