BackgroundHPV vaccination is recommended in France for all adolescents aged 11-14. Coverage has increased over recent years but remains below 50% by age 15, with social disparities by area deprivation level, parental education and income. We analysed the effect of school-wide campaigns on adolescent vaccine uptake and related disparities.MethodsPrevHPV is a controlled cluster-randomised trial to assess the effectiveness and efficiency of a multi-component intervention targeting middle schools and general practitioners. Sixty-one French middle schools were randomised in a partial factorial design to one of six intervention arms, some of which included school-based vaccine campaigns combined with in-class education and motivation. We assessed HPV vaccine status using online questionnaires that were administered in class to pupils (aged 13-15 years) at baseline and after 5 months. Using linear regression, we explored the decomposed effect of campaigns on vaccine uptake and interactions of the effect with sociodemographic variables.ResultsIn total, 2639 adolescents provided complete vaccination data on both questionnaires, with a ≥ 1-dose coverage of 24% at baseline. Among previously unvaccinated pupils (N = 2017), 21% (7%) of girls (boys) in the control group reported receipt of first vaccine dose during the follow-up period, compared to 49% (33%) in arms with vaccine campaigns. Adjusting for baseline vaccine intention, vaccine campaigns increased the 5-month probability of a first dose by 25 (95% confidence interval: 19-31) percentage points compared to the control group. The effect of vaccine campaigns on student-reported vaccine uptake did not substantially vary by school area deprivation level, parental education level, or family multilingualism (compared to French monolingual family).ConclusionsSchool-based campaigns substantially increased vaccine coverage among all adolescents within a short time period. Yet, underlying disparities in HPV vaccination were unchanged.Key messages• School-based vaccine campaigns can quickly increase HPV vaccine uptake among adolescents.• Vaccination campaigns need tailored implementation strategies to eventually reduce social disparities in HPV vaccination.