Discordant vaccine uptake and its determinants among adolescents in a context of high vaccination coverage and longtime immigration: a cross-sectional study in Umbria region, Italy

Introduction Adolescent vaccination is a key public health strategy to ensure protection against vaccine-preventable diseases, including HPV. Although coverage for several adolescent vaccines in Italy is high, complete HPV uptake remains suboptimal, and evidence on overall adolescent vaccination and its determinants is limited. This study assessed full vaccination coverage in Umbria and explored socio-demographic, cultural, and psychosocial factors associated with uptake. Methods A cross-sectional study was conducted during the 2024/2025 school year among 12-year-old adolescents and their parents in Umbria, Italy, using a web-based questionnaire administered through lower secondary schools. Data were collected on vaccination status and key determinants, including health literacy, vaccine knowledge, attitudes, and cultural affiliation, using validated instruments. Adolescents were classified as fully vaccinated if they had received the diphtheria–tetanus–pertussis–polio booster, meningococcal vaccine, and at least one HPV dose. Associations with vaccination status were analyzed using chi-square tests. Results Among 277 adolescent–parent pairs (response rate: 3,9%), 79,9% (95% CI: 74,5%–84,3%) of adolescents were fully vaccinated. Coverage for DTaP-polio and meningococcal vaccines exceeded 86%, while HPV uptake was 69,7% (two doses). No significant associations were observed with socio-demographic characteristics. Vaccination status was significantly associated with cognitive and cultural determinants: higher parental HPV knowledge (p = 0.002) and adolescents’ correct awareness of HPV risks (p = 0.015) were linked to higher uptake, whereas greater general parental vaccine knowledge was paradoxically associated with lower uptake (p = 0.029). Adolescents with an active health orientation were more likely to be fully vaccinated (p = 0.018). Health literacy, vaccine attitudes, and cultural affiliation showed limited or no association. Conclusions A substantial proportion of adolescents remains incompletely vaccinated despite high coverage. Health orientation and HPV knowledge play a central role in uptake. Interventions strengthening health literacy and promoting accurate HPV knowledge may improve adherence to vaccination programs.