Adherence to recommended immunization schedule during adolescence: findings of a cross-sectional study in the Southern part of Italy

Adolescence is a pivotal life stage during which individuals develop health-related attitudes and behaviours that frequently persist into adulthood, making it a crucial period for shaping long-term engagement with preventive care. Despite Italy’s national recommendations for adolescent vaccines (HPV, MenACWY, and the dTap-IPV booster), coverage gaps persist. By analyzing the self-reported vaccination history of university students, this study aims to assess adolescent vaccine adherence, willingness to vaccinate and their predictors to better inform targeted public health interventions. A cross-sectional survey was conducted among university students (aged 18–29 years). An online, anonymous, self-administered questionnaire was developed to gather data on socio-demographic characteristics, past adherence to vaccinations offered during adolescence (i.e., HPV and MenACWY vaccines and the dTap-IPV booster), willingness to get vaccinated, factors influencing vaccination decision making, and sources of information on vaccinations. Among the 527 enrolled participants, 29% reported having received the MenACWY vaccine during adolescence, with the lack of healthcare worker (HCW) recommendation cited as the leading barrier (59.4%). HPV vaccine uptake was the strongest predictor of being vaccinated against MenACWY vaccination. A majority of the students (68.3%) reported receiving the HPV vaccine during adolescence, primarily to prevent HPV-related cancers (55.8%). Female sex, younger age, and higher parental education were positively associated with the HPV vaccine uptake. Additionally, 89.4% received the dTap-IPV booster, and this uptake was positively associated with both HPV and MenACWY vaccination. Notably, one-third (31.1%) reported that an HCW had discouraged vaccination, and even though nearly all (99.4%) cited HCWs as their primary source of information on vaccination. A persistent gap in adolescent vaccination adherence remains, particularly for MenACWY and HPV, driven by unbalanced risk perceptions and frequent missed clinical opportunities by HCWs. Conversely, vaccine mandates ensured high dTap-IPV coverage. The strong correlation across vaccine types highlights the potential of “clustered” immunization behaviors. To bridge these coverage gaps, interventions must strengthen HCW counseling, utilize low-friction delivery models like school-based clinics, and deploy dual-targeted strategies that reframe vaccination as a shared social responsibility.